[gpfsug-discuss] What NSDs does a file have blocks on?

[Buterbaugh, Kevin L]

Hi Kums,

Thanks so much … this gave me exactly what I was looking for and the output was what I suspected I would see.  Unfortunately, that means that the mystery of why we’re having these occasional high I/O wait times persists, but oh well…

Kevin

On Jul 9, 2018, at 3:51 PM, Kumaran Rajaram <kums at us.ibm.com<mailto:kums at us.ibm.com>> wrote:

Hi Kevin,

>>I want to know what NSDs a single file has its’ blocks on?

You may use /usr/lpp/mmfs/samples/fpo/mmgetlocationto obtain the file-to-NSD block layout map. Use the -h option for this tools usage (mmgetlocation -h).

Sample output is below:

# File-system block size is 4MiB and sample file is 40MiB.
# ls -lh /mnt/gpfs3a/data_out/lf
-rw-r--r-- 1 root root 40M Jul  9 16:42 /mnt/gpfs3a/data_out/lf
# du -sh /mnt/gpfs3a/data_out/lf
40M     /mnt/gpfs3a/data_out/lf
# mmlsfs gpfs3a | grep 'Block size'
 -B                 4194304                  Block size

# The file data is striped across 10 x NSDs (DMD_NSDX) constituting the file-system

# /usr/lpp/mmfs/samples/fpo/mmgetlocation -f /mnt/gpfs3a/data_out/lf
[FILE /mnt/gpfs3a/data_out/lf INFORMATION]
         FS_DATA_BLOCKSIZE : 4194304 (bytes)
         FS_META_DATA_BLOCKSIZE : 4194304 (bytes)
         FS_FILE_DATAREPLICA : 1
         FS_FILE_METADATAREPLICA : 1
         FS_FILE_STORAGEPOOLNAME : system
         FS_FILE_ALLOWWRITEAFFINITY : no
         FS_FILE_WRITEAFFINITYDEPTH : 0
         FS_FILE_BLOCKGROUPFACTOR : 1

chunk(s)# 0 (offset 0) : [DMD_NSD5 c72f1m5u37ib0,c72f1m5u39ib0]
chunk(s)# 1 (offset 4194304) : [DMD_NSD6 c72f1m5u39ib0,c72f1m5u37ib0]
chunk(s)# 2 (offset 8388608) : [DMD_NSD7 c72f1m5u37ib0,c72f1m5u39ib0]
chunk(s)# 3 (offset 12582912) : [DMD_NSD8 c72f1m5u39ib0,c72f1m5u37ib0]
chunk(s)# 4 (offset 16777216) : [DMD_NSD9 c72f1m5u37ib0,c72f1m5u39ib0]
chunk(s)# 5 (offset 20971520) : [DMD_NSD10 c72f1m5u39ib0,c72f1m5u37ib0]
chunk(s)# 6 (offset 25165824) : [DMD_NSD1 c72f1m5u37ib0,c72f1m5u39ib0]
chunk(s)# 7 (offset 29360128) : [DMD_NSD2 c72f1m5u39ib0,c72f1m5u37ib0]
chunk(s)# 8 (offset 33554432) : [DMD_NSD3 c72f1m5u37ib0,c72f1m5u39ib0]
chunk(s)# 9 (offset 37748736) : [DMD_NSD4 c72f1m5u39ib0,c72f1m5u37ib0]


[FILE: /mnt/gpfs3a/data_out/lf SUMMARY INFO]
replica1:
        c72f1m5u37ib0,c72f1m5u39ib0: 5 chunk(s)
        c72f1m5u39ib0,c72f1m5u37ib0: 5 chunk(s)

Thanks and Regards,
-Kums


From:        "Buterbaugh, Kevin L" <Kevin.Buterbaugh at Vanderbilt.Edu<mailto:Kevin.Buterbaugh at Vanderbilt.Edu>>
To:        gpfsug main discussion list <gpfsug-discuss at spectrumscale.org<mailto:gpfsug-discuss at spectrumscale.org>>
Date:        07/09/2018 04:05 PM
Subject:        [gpfsug-discuss] What NSDs does a file have blocks on?
Sent by:        gpfsug-discuss-bounces at spectrumscale.org<mailto:gpfsug-discuss-bounces at spectrumscale.org>
________________________________



Hi All,

I am still working on my issue of the occasional high I/O wait times and that has raised another question … I know that I can run mmfileid to see what files have a block on a given NSD, but is there a way to do the opposite?  I.e. I want to know what NSDs a single file has its’ blocks on?  The mmlsattr command does not appear to show this information unless it’s got an undocumented option.  Thanks…

Kevin

—
Kevin Buterbaugh - Senior System Administrator
Vanderbilt University - Advanced Computing Center for Research and Education
Kevin.Buterbaugh at vanderbilt.edu<mailto:Kevin.Buterbaugh at vanderbilt.edu>- (615)875-9633


_______________________________________________
gpfsug-discuss mailing list
gpfsug-discuss at spectrumscale.org<http://spectrumscale.org>
http://gpfsug.org/mailman/listinfo/gpfsug-discuss<https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fgpfsug.org%2Fmailman%2Flistinfo%2Fgpfsug-discuss&data=02%7C01%7CKevin.Buterbaugh%40vanderbilt.edu%7C523052f2a40c48efb5a808d5e5ddc6b0%7Cba5a7f39e3be4ab3b45067fa80faecad%7C0%7C0%7C636667663044944884&sdata=Q2Wg8yDwA9yu%2FZgJXELr7V3qHAY7I7eKPTBHkqVKA5I%3D&reserved=0>


_______________________________________________
gpfsug-discuss mailing list
gpfsug-discuss at spectrumscale.org<http://spectrumscale.org>
https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fgpfsug.org%2Fmailman%2Flistinfo%2Fgpfsug-discuss&data=02%7C01%7CKevin.Buterbaugh%40vanderbilt.edu%7C523052f2a40c48efb5a808d5e5ddc6b0%7Cba5a7f39e3be4ab3b45067fa80faecad%7C0%7C0%7C636667663044944884&sdata=Q2Wg8yDwA9yu%2FZgJXELr7V3qHAY7I7eKPTBHkqVKA5I%3D&reserved=0

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://gpfsug.org/pipermail/gpfsug-discuss_gpfsug.org/attachments/20180709/4299b0be/attachment-0002.htm>