[gpfsug-discuss] AFM cache re-link

[Nick Savva]

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<mailto:vpuvvada at in.ibm.com>)



From:        Nick Savva <nick.savva at adventone.com<mailto:nick.savva at adventone.com>>
To:        "'gpfsug-discuss at spectrumscale.org'" <gpfsug-discuss at spectrumscale.org<mailto: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<mailto: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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