[gpfsug-discuss] AFM cache re-link

[Venkateswara R Puvvada]

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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