[gpfsug-discuss] AFM cache re-link

[Venkateswara R Puvvada]

RO cache filesets doesn't support failover command. Is NICKTESTFSET RO 
mode fileset ?

>The infocenter and documentation say the cache expects home to be empty. 
I did a small test and it seems to work but it may have happened too fast 
for me to notice any data movement. 

mmafmctl failover/resync commands does not remove extra files at home, if 
home is empty this won't be an issue.

~Venkat (vpuvvada at in.ibm.com)



From:   Nick Savva <nick.savva at adventone.com>
To:     gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:   04/24/2018 12:18 PM
Subject:        Re: [gpfsug-discuss] AFM cache re-link
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



The caches are RO. Thanks that’s exactly what I tested, its just the 
infocenter threw me when it said it expects the home to be empty….. 
 
This was the command I used 
 
mmafmctl cachefs1 failover -j NICKTESTFSET  --new-target 
nfs://10.0.0.142/ibm/scalefs2/fsettest 
 
Appreciate the confirmation
 
Nick
 
 
From: gpfsug-discuss-bounces at spectrumscale.org 
<gpfsug-discuss-bounces at spectrumscale.org> On Behalf Of Venkateswara R 
Puvvada
Sent: Monday, 23 April 2018 8:56 PM
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Subject: Re: [gpfsug-discuss] AFM cache re-link
 
What is the fileset mode ? AFM won't attempt to copy the data back to home 
if file data already exists (checks if file size, mtime with nano seconds 
granularity  and number of data blocks allocated are same). For example 
rsync version >= 3.1.0 keeps file mtime in sync with nano seconds 
granularity. Copy the data  from old home to new home and run failover 
command  from cache to avoid resynching the entire data.

~Venkat (vpuvvada at in.ibm.com)



From:        Nick Savva <nick.savva at adventone.com>
To:        "'gpfsug-discuss at spectrumscale.org'" <
gpfsug-discuss at spectrumscale.org>
Date:        04/22/2018 05:48 PM
Subject:        [gpfsug-discuss] AFM cache re-link
Sent by:        gpfsug-discuss-bounces at spectrumscale.org




Hi all,
 
I was always preface my questions with an apology first up if this has 
been covered before.
 
I am curious if anyone has tested relinking an AFM cache to a new home 
where the new home, old home and cache have the exact same data. What is 
the behaviour? 
 
The infocenter and documentation say the cache expects home to be empty. I 
did a small test and it seems to work but it may have happened too fast 
for me to notice any data movement. 
 
If anyone is interested in the use case, I am attempting to avoid pulling 
data from production over the link. The idea is to sync the data locally 
in DR to the cache, and then relink the cache to production. Where prod/dr 
are gpfs filesystems with a replica set of data. Again its to avoid moving 
TB’s across the link that are already there.
 
 
Appreciate the help in advance,
 
Nick
 
 
 
 
 
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