[gpfsug-discuss] Migration policy confusion

Thu Jul 7 15:20:12 BST 2016

At the very least, LOOK at the messages output by the mmapplypolicy 
command at the beginning and end.
The "occupancy" stats for each pool are shown BEFORE and AFTER  the 
command does its work.

In even more detail, it shows you how many files and how many KB of data 
were (or will be or would be) migrated.

Also, options matter.  ReadTheFineManuals.  -I test vs -I defer vs -I yes.

To see exactly which files are being migrated, use -L 2
To see exactly which files are being selected by your rule(s), use -L 3
And for more details about the files being skipped over, etc, etc,   -L 6

Gee, I just checked the doc myself, I forgot some of the details and it's 
pretty good.
Admittedly mmapplypolicy is a complex command.  You can do somethings 
simply, only knowing
a few options and policy rules, BUT...

As my father used to say, "When all else fails, read the directions!"

-L n
Controls the level of information displayed by the mmapplypolicy command. 
Larger values indicate
the display of more detailed information. These terms are used:
candidate file
A file that matches a MIGRATE, DELETE, or LIST policy rule.
chosen file
A candidate file that has been scheduled for action.

These are the valid values for n:
0 Displays only serious errors.
1 Displays some information as the command runs, but not for each file. 
This is the default.
2 Displays each chosen file and the scheduled migration or deletion 
action.
3 Displays the same information as 2, plus each candidate file and the 
applicable rule.
4 Displays the same information as 3, plus each explicitly EXCLUDEed or 
LISTed file, and the
applicable rule.
5 Displays the same information as 4, plus the attributes of candidate and 
EXCLUDEed or LISTed
files.
6 Displays the same information as 5, plus non-candidate files and their 
attributes.

For examples and more information on this flag, see the section: The 
mmapplypolicy -L command in the
IBM Spectrum Scale: Problem Determination Guide.

--marc

From:   "Mark.Bush at siriuscom.com" <Mark.Bush at siriuscom.com>
To:     gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:   07/07/2016 09:17 AM
Subject:        Re: [gpfsug-discuss] Migration policy confusion
Sent by:        gpfsug-discuss-bounces at spectrumscale.org

Thanks Daniel.  I did wait for 15-20 minutes after.

From: <gpfsug-discuss-bounces at spectrumscale.org> on behalf of Daniel 
Kidger <daniel.kidger at uk.ibm.com>
Reply-To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date: Thursday, July 7, 2016 at 8:10 AM
To: "gpfsug-discuss at spectrumscale.org" <gpfsug-discuss at spectrumscale.org>
Cc: "gpfsug-discuss at spectrumscale.org" <gpfsug-discuss at spectrumscale.org>
Subject: Re: [gpfsug-discuss] Migration policy confusion

Mark,
For performance reasons, mmdf gets its data updated asynchronously.
Did you try waiting a few minutes?
Daniel
Error! Filename not specified.

Error! Filename not specified.

Dr Daniel Kidger
IBM Technical Sales Specialist
Software Defined Solution Sales

+44-07818 522 266 
daniel.kidger at uk.ibm.com

----- Original message -----
From: "Mark.Bush at siriuscom.com" <Mark.Bush at siriuscom.com>
Sent by: gpfsug-discuss-bounces at spectrumscale.org
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Cc:
Subject: [gpfsug-discuss] Migration policy confusion
Date: Thu, Jul 7, 2016 2:00 PM

Hello all, I’m struggling trying to understand tiering and policies in 
general in SpecScale.  I have a single filesystem with two pools defined 
(system, GOLD).  The GOLD pool is made up of some faster disks than the 
system pool.  The policy I’m trying to get working is as follows

RULE 'go_gold'
    MIGRATE
        FROM POOL 'system'
    TO POOL 'GOLD'
        WHERE (LOWER(NAME) LIKE '%.perf')

I’m simply trying to get the data to move the NDS’s in GOLD pool.

When I do an mmapplypolicy, mmlsattr shows that it’s now in the GOLD pool 
but when I do a mmdf the data shows 100% free still.  I tried a 
mmrestripefs as well and no change to the mmdf output.  Am I missing 
something here?  Is this just normal behavior and the blocks will get 
moved at some other time?  I guess I was expecting instant gratification 
and that those files would have been moved to the correct NSD.

Mark R. Bush | Solutions Architect
Mobile: 210.237.8415 | mark.bush at siriuscom.com
Sirius Computer Solutions | www.siriuscom.com
10100 Reunion Place, Suite 500, San Antonio, TX 78216 

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