[gpfsug-discuss] Using AFM to migrate files.

[Yaron Daniel]

Hi

Does you use NFSv4 acls in your old cluster ?
 
Regards
 


 
 
Yaron Daniel
 94 Em Ha'Moshavot Rd

Server, Storage and Data Services - Team Leader  
 Petach Tiqva, 49527
Global Technology Services
 Israel
Phone:
+972-3-916-5672
 
 
Fax:
+972-3-916-5672
 
 
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IBM Israel
 
 
 
 

 



From:   Peter Childs <p.childs at qmul.ac.uk>
To:     gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:   10/19/2016 05:34 PM
Subject:        [gpfsug-discuss] Using AFM to migrate files.
Sent by:        gpfsug-discuss-bounces at spectrumscale.org




We are planning to use AFM to migrate our old GPFS file store to a new 
GPFS file store. This will give us the advantages of Spectrum Scale (GPFS) 
4.2, such as larger block and inode size. I would like to attempt to gain 
some insight on my plans before I start.

The old file store was running GPFS 3.5 with 512 byte inodes and 1MB block 
size. We have now upgraded it to 4.1 and are working towards 4.2 with 
300TB of files. (385TB max space) this is so we can use both the old and 
new storage via multi-cluster.

We are moving to a new GPFS cluster so we can use the new protocol nodes 
eventually and also put the new storage machines as cluster managers, as 
this should be faster and future proof

The new hardware has 1PB of space running GPFS 4.2

We have multiple filesets, and would like to maintain our namespace as far 
as possible.

My plan was to.

1. Create a read-only (RO) AFM cache on the new storage (ro)
2a. Move old fileset and replace with SymLink to new.
2b. Convert RO AFM to Local Update (LU) AFM pointing to new parking area 
of old files.
2c. move user access to new location in cache.
3. Flush everything into cache and disconnect.

I've read the docs including the ones on migration but it's not clear if 
it's safe to move the home of a cache and update the target. It looks like 
it should be possible and my tests say it works.

An alternative plan is to use a Independent Writer (IW) AFM Cache to move 
the home directories which are pointed to by LDAP. Hence we can move users 
one at a time and only have to drain the HPC cluster at the end to 
disconnect the cache. I assume that migrating users over an Independent 
Writer is safe so long as the users don't use both sides of the cache at 
once (ie home and target)

I'm also interested in any recipe people have on GPFS policies to preseed 
and flush the cache.

We plan to do all the migration using AFM over GPFS we're not currently 
using NFS and have no plans to start. I believe using GPFS is the faster 
method to preform the migration.

Any suggestions and experience of doing similar migration jobs would be 
helpful.

Peter Childs
Research Storage
ITS Research and Teaching Support
Queen Mary, University of London

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