<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">Which version are you running?<div><br></div><div>I was involved on a big for compressed file sets and snapshots that were related to what you see. <br><br><div dir="ltr">--<div>Cheers</div></div><div dir="ltr"><br><blockquote type="cite">On 28. Nov 2019, at 14.57, Cregan, Bob <b.cregan@imperial.ac.uk> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Hi </div><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> Sounds logical - except the snap metadata does not have the compression flag set. So if the inode now points to a set of compressed blocks how does the client know to decompress it?</div><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br></div><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">After compression of an existing file we get in the snap</div><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br></div><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">-bash-4.2$ mmlsattr -L .snapshots/@GMT-2019.11.27-19.30.14/UserGuide_13.06.pdf</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">file name:<span>
</span>.snapshots/@GMT-2019.11.27-19.30.14/UserGuide_13.06.pdf</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">metadata replication: 2 max 2</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">data replication:
<span> </span>1 max 3</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">immutable:<span>
</span>no</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">appendOnly:
<span> </span>no</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">flags:
<span> </span></span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">storage pool name:<span>
</span>sata1</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">fileset name:
<span> </span>userdirs</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">snapshot name:<span>
</span>@GMT-2019.11.27-19.30.14</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">creation time:<span>
</span>Tue Mar<span> </span>5 16:16:40 2019</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">Misc attributes:<span>
</span>ARCHIVE</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">Encrypted:<span>
</span>no</span></p><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br></div> and the original file is definitely compressed.</div><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br></div><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">-bash-4.2$ mmlsattr -L UserGuide_13.06.pdf<span> </span></span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">file name:<span>
</span>UserGuide_13.06.pdf</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">metadata replication: 2 max 2</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">data replication:
<span> </span>1 max 3</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">immutable:<span>
</span>no</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">appendOnly:
<span> </span>no</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">flags:
<span> </span></span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">storage pool name:<span>
</span>sata1</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">fileset name:
<span> </span>userdirs</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">snapshot name:
<span> </span></span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">creation time:<span>
</span>Tue Mar<span> </span>5 16:16:40 2019</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">Misc attributes:<span>
</span>ARCHIVE COMPRESSION (library z)</span></p><p style="margin: 0px; font: 11px Menlo; margin: 0px"><span style="font-variant-ligatures: no-common-ligatures; font-variant-ligatures: no-common-ligatures">Encrypted:<span>
</span>no</span></p><br></div><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">Bob</div><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br></div><div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"><br></div><div id="Signature"><div id="divtagdefaultwrapper" dir="ltr" style="font-size:12pt; color:rgb(0,0,0); font-family:Calibri,Helvetica,sans-serif,Helvetica,EmojiFont,"Apple Color Emoji","Segoe UI Emoji",NotoColorEmoji,"Segoe UI Symbol","Android Emoji",EmojiSymbols"><p style="margin-top: 0px; margin-bottom: 0px;"><br></p><p style="margin-top: 0px; margin-bottom: 0px;"></p><p style="margin-top: 0px; margin-bottom: 0px;margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><strong><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:rgb(0,111,201); font-size:10pt">Bob Cregan</span></strong><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black; font-size:10pt"><br>HPC Systems Analyst</span><span style="font-family:Calibri,sans-serif,serif,EmojiFont; color:black"></span></p><span style="font-size:10pt"></span><p style="margin-top: 0px; margin-bottom: 0px;margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><span style="font-size:10pt"></span><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black; font-size:10pt">Information & Communication Technologies</span><span style="font-family:Calibri,sans-serif,serif,EmojiFont; color:black"></span></p><span style="font-size:10pt"></span><p style="margin-top: 0px; margin-bottom: 0px;margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><span style="font-size:10pt"></span><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black"><span style="font-size:10pt">Imperial College London, </span><br><span style="font-size:10pt">South Kensington Campus London, SW7 2AZ</span><br><span style="font-size:10pt">T: 07712388129</span><br><span style="font-size:10pt">E: b.cregan@imperial.ac.uk</span><br><span style="font-size:10pt"></span></span></p><span style="font-size:10pt"></span><span id="ms-rterangepaste-start"></span><span style="font-size:10pt"></span><p style="margin-top: 0px; margin-bottom: 0px;margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><span style="font-size:10pt"></span><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black"><span style="font-size:10pt">W: </span><a href="http://www.imperial.ac.uk/ict/rcs" target="_blank" rel="noopener noreferrer" id="LPNoLP"><span style="font-size:10pt">www.imperial.ac.uk/</span><span style="font-size:10pt">ict</span><span style="font-size:10pt">/</span><span style="font-size:10pt">rcs</span></a></span><span style="font-family:Calibri,sans-serif,serif,EmojiFont; color:black"></span></p><span style="font-size:10pt"></span><p style="margin-top: 0px; margin-bottom: 0px;margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33); line-height:24px"><sub><span style="font-size:10pt; line-height:23px; font-family:Calibri,sans-serif,serif,EmojiFont; color:rgb(31,73,125)"><div><Outlook-1505984389.png></div> </span></sub><span style="font-size:10pt; line-height:23px; font-family:Arial,sans-serif,serif,EmojiFont; color:black">@imperialRCS
@imperialRSE</span><span style="font-family:Calibri,sans-serif,serif,EmojiFont; color:black"></span></p><p style="margin-top: 0px; margin-bottom: 0px;margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><div><Outlook-1505983882.png></div><br></p><span id="ms-rterangepaste-end"></span><p style="margin-top: 0px; margin-bottom: 0px;margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33); line-height:24px"></p><br><p style="margin-top: 0px; margin-bottom: 0px;"></p><p style="margin-top: 0px; margin-bottom: 0px;"><span></span></p></div></div><div id="appendonsend"></div><hr style="display:inline-block;width:98%" tabindex="-1"><div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> gpfsug-discuss-bounces@spectrumscale.org <gpfsug-discuss-bounces@spectrumscale.org> on behalf of Daniel Kidger <daniel.kidger@uk.ibm.com><br><b>Sent:</b> 28 November 2019 12:30<br><b>To:</b> gpfsug-discuss@spectrumscale.org <gpfsug-discuss@spectrumscale.org><br><b>Cc:</b> gpfsug-discuss@spectrumscale.org <gpfsug-discuss@spectrumscale.org><br><b>Subject:</b> Re: [gpfsug-discuss] Compression question</font><div> </div></div><div><table class="x_MsoNormalTable" cellspacing="0" cellpadding="0" border="1" style=""><tbody><tr style=""><td style="border-top:#f0f0f0; border-right:#f0f0f0; background:#ffffcc; border-bottom:#f0f0f0; padding-bottom:0cm; padding-top:0cm; padding-left:0cm; border-left:#f0f0f0; padding-right:0cm"><p class="x_MsoNormal" style="margin:0cm 0cm 0pt"><span style="font-size:12pt; font-family:"Arial",sans-serif"><font size="2"><font color="#ff0000">Caution
</font><font color="#000000">- This email from daniel.kidger@uk.ibm.com originated outside Imperial
</font></font></span></p></td></tr></tbody></table><p> </p><div class="x_socmaildefaultfont" dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:9pt"><div dir="ltr">Alexander,</div><div dir="ltr"> </div><div dir="ltr">Can you then confirm then that the inodes in the snapshot will now point to fewer but compressed blocks ?</div><div dir="ltr"><div class="x_socmaildefaultfont" dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div class="x_socmaildefaultfont" dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div class="x_socmaildefaultfont" dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div class="x_socmaildefaultfont" dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div class="x_socmaildefaultfont" dir="ltr"><div class="x_socmaildefaultfont" dir="ltr"><div class="x_socmaildefaultfont" dir="ltr"><div class="x_socmaildefaultfont" dir="ltr"><div class="x_socmaildefaultfont" dir="ltr"><div class="x_socmaildefaultfont" dir="ltr"><div class="x_socmaildefaultfont" dir="ltr"><div class="x_socmaildefaultfont" dir="ltr"><div class="x_socmaildefaultfont" dir="ltr"><div class="x_socmaildefaultfont" dir="ltr"><div class="x_socmaildefaultfont" dir="ltr"><div dir="ltr" style="margin-top:20px"><div style="margin-top:10px"><div style="font-family:sans-serif; font-size:8pt; margin-bottom:0.0001pt; line-height:normal"><span style="font-size:1.000em">Daniel</span></div><div style="font-family:sans-serif; font-size:8pt; margin-bottom:0.0001pt; line-height:normal"> </div><div style="margin-bottom:0.0001pt; line-height:normal"><font color="#19A9F3" size="3" style="font-family:"Helvetica Neue",Helvetica,Arial,"Lucida Grande",sans-serif; font-size:8pt; outline:none">_________________________________________________________</font><br style="outline:none"><font color="#808080" face="Arial" size="2"><span style=""><b>Daniel Kidger</b></span></font></div><div style="margin-bottom:0.0001pt; line-height:normal"><span style="outline:none; color:rgb(18,18,18); font-size:10.666666984558105px"><span style="outline:none; font-size:7.5pt">IBM Technical Sales Specialist</span></span></div><div style="margin-bottom:0.0001pt; line-height:normal"><span style="outline:none; color:rgb(18,18,18); font-size:10.666666984558105px"><span style="outline:none; font-size:7.5pt">Spectrum Scale, Spectrum NAS and IBM Cloud Object Store<br style="outline:none"><br style="outline:none"><span style="font-size:0.857em">+</span></span></span><span style="font-size:0.857em"><span style="outline:none; font-family:sans-serif; color:rgb(95,95,95)"><span style="outline:none; font-family:Verdana,Geneva,sans-serif"><span style="outline:none">44-(0)7818
522 266 </span></span></span></span><br style="outline:none; color:rgb(18,18,18); font-family:sans-serif; font-size:10.666666984558105px"><span style="outline:none; font-family:sans-serif; font-size:10.666666984558105px; color:rgb(95,95,95)"><span style="outline:none; font-family:Arial,Helvetica,sans-serif"><span style="outline:none; font-size:8pt">daniel.kidger@uk.ibm.com</span></span></span><table border="0" style="border-collapse:collapse; border-color:#696969; table-layout:fixed; width:264px; word-wrap:break-word"><tbody><tr><td style="overflow:hidden; width:88px; border-color:#696969"><a href="https://www.youracclaim.com/badges/687cf790-fe65-4a92-b129-d23ae41862ac/public_url" target="_blank"><img alt="" style="width:88px; height:88px" src="https://images.youracclaim.com/images/c49300ae-d13e-4071-90f5-15f59d199c9e/IBM%2BVolunteers%2BGold%2Bv6.png" data-unique-identifier=""></a></td><td style="overflow:hidden; width:88px; border-color:#696969"><a href="https://www.youracclaim.com/badges/8153c6a7-3e02-40be-87ee-24e27ae9459c/public_url" target="_blank"><img alt="" style="width:88px; height:88px" src="https://images.youracclaim.com/images/f2539224-f951-46b4-b376-b88f21c2be98/IBM-Selling-Certification---Level-1.png" data-unique-identifier=""></a></td><td style="overflow:hidden; width:88px; border-color:#696969"><a href="https://www.youracclaim.com/badges/78197e2c-4277-4ec9-808b-ad6abe1e1b16/public_url" target="_blank"><img alt="" style="width:88px; height:88px" src="https://images.youracclaim.com/images/ea52b12f-97ac-4e72-8d24-b0ced8054e7d/Storage%2BTechnical%2BV1.png" data-unique-identifier=""></a></td></tr></tbody></table><div> </div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div><div dir="ltr"> </div><div dir="ltr"> </div><blockquote dir="ltr" style="border-left:solid #aaaaaa 2px; margin-left:5px; padding-left:5px; direction:ltr; margin-right:0px">----- Original message -----<br>From: "Alexander Wolf" <A.Wolf-Reber@de.ibm.com><br>Sent by: gpfsug-discuss-bounces@spectrumscale.org<br>To: gpfsug-discuss@spectrumscale.org<br>Cc:<br>Subject: [EXTERNAL] Re: [gpfsug-discuss] Compression question<br>Date: Thu, Nov 28, 2019 12:21<br>
<div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10pt"><div dir="ltr">I just tested this. Compressing a file did free up space in the file system. Looks like our compression code does not trigger COW on the snapshot. You can test this yourself by looking into mmlssnapshot -d (please not on a large production fs,
this command is expensive).</div><div dir="ltr"> </div><div dir="ltr"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10pt"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10pt"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div dir="ltr" style="font-family:Arial; font-size:10.5pt"><div dir="ltr" style="font-family:Arial; font-size:10.5pt"><div dir="ltr"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Arial" size="2">Mit freundlichen Grüßen / Kind regards</font></font></font><p><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><div><Image.15749424191280.png></div></font></font></p><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"></font></font><table border="0" cellpadding="0" cellspacing="0"><tbody><tr valign="top"><td valign="middle" width="202"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><div><Image.15749424191281.png></div></font></font><ul style="padding-left:0pt; margin-left:0px; list-style-type:none"><li><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"> </font></li></ul><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"></font></font></td><td valign="middle" width="31"><ul style="padding-left:0pt; margin-left:0px; list-style-type:none"><li><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font size="3"> </font></font></font></li></ul></td><td valign="middle" width="464"><ul style="padding-left:0pt; margin-left:0px; list-style-type:none"><li><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><b><font face="Arial" size="3">Dr. Alexander Wolf-Reber</font></b><br><font face="Arial" size="1">Spectrum Scale Release Lead Architect<br>Department M069 / Spectrum Scale Software Development<br><br>+49-160-90540880<br>a.wolf-reber@de.ibm.com</font></font></font></li></ul></td></tr></tbody></table><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><div><Image.15749424191282.png></div></font></font><div><a href="https://www.ibm.com/privacy/us/en/" rel="noopener noreferrer" target="_blank">IBM Data Privacy Statement</a></div><p><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font color="#999999" face="Arial" size="1">IBM Deutschland Research & Development GmbH / Vorsitzende
des Aufsichtsrats: Matthias Hartmann / Geschäftsführung: Dirk Wittkopp<br>Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294</font></font></font></p><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"><font face="Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size="2"></font></font></div></div></div></div></div></div></div></div></div></div><div dir="ltr"> </div><div dir="ltr"> </div><blockquote dir="ltr" style="border-left:solid #aaaaaa 2px; margin-left:5px; padding-left:5px; direction:ltr; margin-right:0px">----- Original message -----<br>From: "Luis Bolinches" <luis.bolinches@fi.ibm.com><br>Sent by: gpfsug-discuss-bounces@spectrumscale.org<br>To: gpfsug-discuss@spectrumscale.org<br>Cc: gpfsug-discuss@spectrumscale.org<br>Subject: [EXTERNAL] Re: [gpfsug-discuss] Compression question<br>Date: Thu, Nov 28, 2019 11:47<br>
<div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10pt"><div dir="ltr">Hi</div><div dir="ltr"> </div><div dir="ltr">Same principle COW. The data blocks do not get modified.</div><div dir="ltr"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10pt"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10pt"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div dir="ltr" style="font-family:Arial,Helvetica,sans-serif; font-size:10.5pt"><div dir="ltr"><div style="font-size:12pt; font-weight:bold; font-family:sans-serif; color:#7C7C5F"><span style="font-size:10pt"><font face="Arial">--<br>Ystävällisin terveisin / Kind regards / Saludos cordiales / Salutations</font> / Salutacions<br><font face="Arial">Luis Bolinches</font></span></div><div style="font-size:12pt; font-weight:bold; font-family:sans-serif; color:#7C7C5F"><span style="font-size:10pt"><font face="Arial">Consultant IT Specialist</font><br><font face="Arial">Mobile Phone: +358503112585</font><br><a href="https://www.youracclaim.com/user/luis-bolinches" rel="noopener" target="_blank"><b><font face="Arial">https://www.youracclaim.com/user/luis-bolinches</font></b></a><br><br><b><font color="#7C7C5F" face="Arial">"If you always give you will always have" -- Anonymous</font></b></span></div><div style="font-size:8pt; font-family:sans-serif; margin-top:10px"><div> </div></div></div></div></div></div></div></div></div><div dir="ltr"> </div><div dir="ltr"> </div><blockquote dir="ltr" style="border-left:solid #aaaaaa 2px; margin-left:5px; padding-left:5px; direction:ltr; margin-right:0px">----- Original message -----<br>From: "Cregan, Bob" <b.cregan@imperial.ac.uk><br>Sent by: gpfsug-discuss-bounces@spectrumscale.org<br>To: gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br>Cc:<br>Subject: [EXTERNAL] Re: [gpfsug-discuss] Compression question<br>Date: Thu, Nov 28, 2019 12:06 PM<br> <br><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">Just to clarify this is SS compression, so </div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"> </div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">mmchattr --compression yes <filename></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"> </div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">or an ILM equivalent</div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"> </div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">So not a regular modification.</div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"> </div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">Bob</div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"> </div><div id="x_Signature"><div dir="ltr" id="x_divtagdefaultwrapper" style="font-size:12pt; color:rgb(0,0,0); font-family:Calibri,Helvetica,sans-serif,Helvetica,EmojiFont,"Apple Color Emoji","Segoe UI Emoji",NotoColorEmoji,"Segoe UI Symbol","Android Emoji",EmojiSymbols"><p style="margin-top:0px; margin-bottom:0px"> </p><p style="margin-top:0px; margin-bottom:0px"> </p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><strong><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:rgb(0,111,201); font-size:10pt">Bob Cregan</span></strong><br><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black; font-size:10pt">HPC Systems Analyst</span></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black; font-size:10pt">Information & Communication Technologies</span></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black"><span style="font-size:10pt">Imperial College London, </span><br><span style="font-size:10pt">South Kensington Campus London, SW7 2AZ</span><br><span style="font-size:10pt">T: 07712388129</span><br><span style="font-size:10pt">E: b.cregan@imperial.ac.uk</span></span></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black"><span style="font-size:10pt">W: </span><a href="http://www.imperial.ac.uk/ict/rcs" id="LPNoLP" rel="noopener noreferrer" target="_blank"><span style="font-size:10pt">www.imperial.ac.uk/</span><span style="font-size:10pt">ict</span><span style="font-size:10pt">/</span><span style="font-size:10pt">rcs</span></a></span></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33); line-height:24px"><sub><span style="font-size:10pt; line-height:23px; font-family:Calibri,sans-serif,serif,EmojiFont; color:rgb(31,73,125)"><div><Image.f7e9a6a7-c4ab-4a2c-a979-4513774aa054.png></div> </span></sub><span style="font-size:10pt; line-height:23px; font-family:Arial,sans-serif,serif,EmojiFont; color:black">@imperialRCS
@imperialRSE</span></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><div><Image.dbd2fd87-b9f2-4b15-903f-c74c7b7298d3.png></div></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33); line-height:24px"> </p>
<p style="margin-top:0px; margin-bottom:0px"> </p><p style="margin-top:0px; margin-bottom:0px"> </p></div></div><div id="x_appendonsend"> </div><hr tabindex="-1" style="display:inline-block; width:98%"><div dir="ltr" id="x_divRplyFwdMsg"><font color="#000000" face="Calibri, sans-serif" style="font-size:11pt"><b>From:</b> Cregan, Bob<br><b>Sent:</b> 28 November 2019 09:43<br><b>To:</b> gpfsug main discussion list <gpfsug-discuss@spectrumscale.org><br><b>Subject:</b> Compression question</font><div> </div></div><div dir="ltr"><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">Hi All,</div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"> Can someone answer the following question on compression in a snapshot context? We have tried various experiments and they are inconclusive - too tedious to go into the detail.</div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"> </div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"><div style="margin:0px; font-size:12pt; font-family:Calibri,Arial,Helvetica,sans-serif; color:black; background-color:rgb(255,255,255)">What happens to the snapshot when a file is compressed in SS? The logic as I see it is </div><div style="margin:0px; font-size:12pt; font-family:Calibri,Arial,Helvetica,sans-serif; color:black; background-color:rgb(255,255,255)"> </div><div style="margin:0px; font-size:12pt; font-family:Calibri,Arial,Helvetica,sans-serif; color:black; background-color:rgb(255,255,255)">####### In a non compressed situation ###############</div><div style="margin:0px; font-size:12pt; font-family:Calibri,Arial,Helvetica,sans-serif; color:black; background-color:rgb(255,255,255)"> </div><div style="margin:0px; font-size:12pt; font-family:Calibri,Arial,Helvetica,sans-serif; color:black; background-color:rgb(255,255,255)">1) create a file,</div><div style="margin:0px; font-size:12pt; font-family:Calibri,Arial,Helvetica,sans-serif; color:black; background-color:rgb(255,255,255)">2) create a snapshot.</div><div style="margin:0px; font-size:12pt; font-family:Calibri,Arial,Helvetica,sans-serif; color:black; background-color:rgb(255,255,255)">3) modify a file in a normal way - the blocks on disk are changed and the old blocks are then written to the snap. </div><div style="margin:0px; font-size:12pt; font-family:Calibri,Arial,Helvetica,sans-serif; color:black; background-color:rgb(255,255,255)"> </div><div style="margin:0px; font-size:15px; color:rgb(32,31,30); background-color:rgb(255,255,255)"><div dir="ltr" style="margin:0px; font-size:12pt; font-family:Calibri,Helvetica,sans-serif,Helvetica,EmojiFont,"Apple Color Emoji","Segoe UI Emoji",NotoColorEmoji,"Segoe UI Symbol","Android Emoji",EmojiSymbols; color:black"><p style="margin-top:0px; margin-bottom:0px">######In a compressed situation ############</p><p style="margin-top:0px; margin-bottom:0px"> </p><div style="margin:0px"><div style="margin:0px; font-family:Calibri,Arial,Helvetica,sans-serif">1) create a file,</div><div style="margin:0px; font-family:Calibri,Arial,Helvetica,sans-serif">2) create a snapshot.</div><div style="margin:0px; font-family:Calibri,Arial,Helvetica,sans-serif">3) Compress the file. Now IBM says the blocks are rewritten when the file is compressed. So do the old uncompressed blocks go into the snap? If so we now have 2 copies of the file and unless
the compression > 50% we have used more space until the snap is deleted.</div><div style="margin:0px; font-family:Calibri,Arial,Helvetica,sans-serif"> </div><div style="margin:0px; font-family:Calibri,Arial,Helvetica,sans-serif">You get the space back in the end, but if you are in a tight situation then potentially compression might not work for you in the short term.</div></div></div></div></div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">Thanks</div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"> </div><div style="font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">Bob</div><div id="x_x_Signature"><div dir="ltr" id="x_x_divtagdefaultwrapper" style="font-size:12pt; color:rgb(0,0,0); font-family:Calibri,Helvetica,sans-serif,Helvetica,EmojiFont,"Apple Color Emoji","Segoe UI Emoji",NotoColorEmoji,"Segoe UI Symbol","Android Emoji",EmojiSymbols"><p style="margin-top:0px; margin-bottom:0px"> </p><p style="margin-top:0px; margin-bottom:0px"> </p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><strong><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:rgb(0,111,201); font-size:10pt">Bob Cregan</span></strong><br><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black; font-size:10pt">HPC Systems Analyst</span></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black; font-size:10pt">Information & Communication Technologies</span></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black"><span style="font-size:10pt">Imperial College London, </span><br><span style="font-size:10pt">South Kensington Campus London, SW7 2AZ</span><br><span style="font-size:10pt">T: 07712388129</span><br><span style="font-size:10pt">E: b.cregan@imperial.ac.uk</span></span></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><span style="font-family:Arial,sans-serif,serif,EmojiFont; color:black"><span style="font-size:10pt">W: </span><a href="http://www.imperial.ac.uk/ict/rcs" id="LPNoLP" rel="noopener noreferrer" target="_blank"><span style="font-size:10pt">www.imperial.ac.uk/</span><span style="font-size:10pt">ict</span><span style="font-size:10pt">/</span><span style="font-size:10pt">rcs</span></a></span></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33); line-height:24px"><sub><span style="font-size:10pt; line-height:23px; font-family:Calibri,sans-serif,serif,EmojiFont; color:rgb(31,73,125)"><div><Image.ba38b5d6-12d6-476a-bcd8-7d647bfab5b3.png></div> </span></sub><span style="font-size:10pt; line-height:23px; font-family:Arial,sans-serif,serif,EmojiFont; color:black">@imperialRCS
@imperialRSE</span></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33)"><div><Image.e34493c2-d35b-4fff-a6df-ce87e2ae5ed4.png></div></p><p style="margin-top:0px; margin-bottom:0px; margin:0cm 0cm 0.0001pt; font-size:12pt; font-family:"Times New Roman",serif; color:rgb(33,33,33); line-height:24px"> </p>
<p style="margin-top:0px; margin-bottom:0px"> </p><p style="margin-top:0px; margin-bottom:0px"> </p></div></div></div><div><font face="Default Monospace,Courier New,Courier,monospace" size="2">_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at spectrumscale.org<br><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss" target="_blank">http://gpfsug.org/mailman/listinfo/gpfsug-discuss</a> </font></div></blockquote><div dir="ltr"> </div></div><br>Ellei edellä ole toisin mainittu: / Unless stated otherwise above:<br>Oy IBM Finland Ab<br>PL 265, 00101 Helsinki, Finland<br>Business ID, Y-tunnus: 0195876-3<br>Registered in Finland<br>
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