[gpfsug-discuss] Hardware refresh -

Shankar Balasubramanian shankbal at in.ibm.com
Thu Oct 13 11:43:23 BST 2016


Please note - though one of the supported use case of AFM is such migration
scenarios, infact AFM does particularly well in faithfully migrating the
data when the source and destination cluster are GPFS, the scalability of
this solution for multi million/multi terabyte file systems has its own set
of challenges. These have to carefully understood and checked if AFM will
fit the bill.


Best Regards,
Shankar Balasubramanian
STSM, AFM & Async DR Development
IBM Systems
Bangalore - Embassy Golf Links
India





From:	"Marc A Kaplan" <makaplan at us.ibm.com>
To:	gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:	10/12/2016 11:25 PM
Subject:	Re: [gpfsug-discuss] Hardware refresh -
Sent by:	gpfsug-discuss-bounces at spectrumscale.org



Yes, you can AFM within a single cluster, in fact with just a single node.
I just set this up on my toy system:

[root at bog-wifi cmvc]# mmlsfileset yy afmlu --afm
Filesets in file system 'yy':
Name                     Status    Path
afmTarget
afmlu                    Linked    /yy/afmlu
gpfs:///xx

[root at bog-wifi cmvc]# mount
  ...
yy on /yy type gpfs (rw,relatime,seclabel)
xx on /xx type gpfs (rw,relatime,seclabel)

[root at bog-wifi cmvc]# mmafmctl yy getstate
Fileset Name    Fileset Target                                Cache State
Gateway Node    Queue Length   Queue numExec
------------    --------------                                -------------
------------    ------------   -------------
afmlu           gpfs:///xx                                    Active
bog-wifi        0              7

So, you may add nodes, add disks to an existing cluster, upgrade your
software, define a new FS,
migrate data from an old FS to a new FS
then delete nodes and disks that are no longer needed...



From:        Stephen Ulmer <ulmer at ulmer.org>
To:        gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:        10/11/2016 09:30 PM
Subject:        Re: [gpfsug-discuss] Hardware refresh
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



I think that the OP was asking why not expand the existing cluster with the
new hardware, and just make a new FS?

I’ve not tried to make a cluster talk AFM to itself yet. If that’s
impossible, then there’s one good reason to make a new cluster (to use AFM
for migration).

Liberty,

--
Stephen



On Oct 11, 2016, at 8:40 PM, Mark.Bush at siriuscom.comwrote:

Only compelling reason for new cluster would be old hardware is EOL or no
longer want to pay maintenance on it.

From: <gpfsug-discuss-bounces at spectrumscale.org> on behalf of Marc A Kaplan
<makaplan at us.ibm.com>
Reply-To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date: Tuesday, October 11, 2016 at 2:58 PM
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Subject: Re: [gpfsug-discuss] Hardware refresh

New FS? Yes there are some good reasons.
New cluster?  I did not see a compelling argument either way.



From:        "Mark.Bush at siriuscom.com" <Mark.Bush at siriuscom.com>
To:        gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:        10/11/2016 03:34 PM
Subject:        Re: [gpfsug-discuss] Hardware refresh
Sent by:        gpfsug-discuss-bounces at spectrumscale.org





Ok.  I think I am hearing that a new cluster with a new FS and copying data
from old to new cluster is the best way forward.  Thanks everyone for your
input.

From: <gpfsug-discuss-bounces at spectrumscale.org> on behalf of Yuri L
Volobuev <volobuev at us.ibm.com>
Reply-To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date: Tuesday, October 11, 2016 at 12:22 PM
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Subject: Re: [gpfsug-discuss] Hardware refresh



This depends on the committed cluster version level (minReleaseLevel) and
file system format. Since NFSv2 is an on-disk format change, older code
wouldn't be able to understand what it is, and thus if there's a
possibility of a downlevel node looking at the NSD, the NFSv1 format is
going to be used. The code does NSDv1<->NSDv2 conversions under the covers
as needed when adding an empty NSD to a file system.

I'd strongly recommend getting a fresh start by formatting a new file
system. Many things have changed over the course of the last few years. In
particular, having a 4K-aligned file system can be a pretty big deal,
depending on what hardware one is going to deploy in the future, and this
is something that can't be bolted onto an existing file system. Having 4K
inodes is very handy for many reasons. New directory format and NSD format
changes are attractive, too. And disks generally tend to get larger with
time, and at some point you may want to add a disk to an existing storage
pool that's larger than the existing allocation map format allows.
Obviously, it's more hassle to migrate data to a new file system, as
opposed to extending an existing one. In a perfect world, GPFS would offer
a conversion tool that seamlessly and robustly converts old file systems,
making them as good as new, but in the real world such a tool doesn't
exist. Getting a clean slate by formatting a new file system every few
years is a good long-term investment of time, although it comes
front-loaded with extra work.

yuri

<image001.gif>Aaron Knister ---10/10/2016 04:45:31 PM---Can one format
NSDv2 NSDs and put them in a filesystem with NSDv1 NSD's? -Aaron

From: Aaron Knister <aaron.s.knister at nasa.gov>
To: <gpfsug-discuss at spectrumscale.org>,
Date: 10/10/2016 04:45 PM
Subject: Re: [gpfsug-discuss] Hardware refresh
Sent by: gpfsug-discuss-bounces at spectrumscale.org








Can one format NSDv2 NSDs and put them in a filesystem with NSDv1 NSD's?

-Aaron

On 10/10/16 7:40 PM, Luis Bolinches wrote:
> Hi
>
> Creating a new FS sounds like a best way to go. NSDv2 being a very good
> reason to do so.
>
> AFM for migrations is quite good, latest versions allows to use NSD
> protocol for mounts as well. Olaf did a great job explaining this
> scenario on the redbook chapter 6
>
> http://www.redbooks.ibm.com/abstracts/sg248254.html?Open
>
> --
> Cheers
>
> On 10 Oct 2016, at 23.05, Buterbaugh, Kevin L
> <Kevin.Buterbaugh at Vanderbilt.Edu
> <mailto:Kevin.Buterbaugh at Vanderbilt.Edu>> wrote:
>
>> Hi Mark,
>>
>> The last time we did something like this was 2010 (we’re doing rolling
>> refreshes now), so there are probably lots of better ways to do this
>> than what we did, but we:
>>
>> 1) set up the new hardware
>> 2) created new filesystems (so that we could make adjustments we
>> wanted to make that can only be made at FS creation time)
>> 3) used rsync to make a 1st pass copy of everything
>> 4) coordinated a time with users / groups to do a 2nd rsync when they
>> weren’t active
>> 5) used symbolic links during the transition (i.e. rm -rvf
>> /gpfs0/home/joeuser; ln -s /gpfs2/home/joeuser /gpfs0/home/joeuser)
>> 6) once everybody was migrated, updated the symlinks (i.e. /home
>> became a symlink to /gpfs2/home)
>>
>> HTHAL…
>>
>> Kevin
>>
>>> On Oct 10, 2016, at 2:56 PM, Mark.Bush at siriuscom.com
>>> <mailto:Mark.Bush at siriuscom.com> wrote:
>>>
>>> Have a very old cluster built on IBM X3650’s and DS3500.  Need to
>>> refresh hardware.  Any lessons learned in this process?  Is it
>>> easiest to just build new cluster and then use AFM?  Add to existing
>>> cluster then decommission nodes?  What is the recommended process for
>>> this?
>>>
>>>
>>> Mark
>>>
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>>
>>>> Kevin Buterbaugh - Senior System Administrator
>> Vanderbilt University - Advanced Computing Center for Research and
>> Education
>> Kevin.Buterbaugh at vanderbilt.edu
>> <mailto:Kevin.Buterbaugh at vanderbilt.edu> - (615)875-9633
>>
>>
>>
>
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