[gpfsug-discuss] Data Replication
Marc A Kaplan
makaplan at us.ibm.com
Thu Sep 1 00:40:13 BST 2016
You can leave out the WHERE ... AND POOL_NAME LIKE 'deep' - that is
redundant with the FROM POOL 'deep' clause.
In fact at a slight additional overhead in mmapplypolicy processing due to
begin checked a little later in the game, you can leave out
MISC_ATTRIBUTES NOT LIKE '%2%' since
the code is smart enough to not operate on files already marked as
replicate(2).
I believe mmapplypolicy .... -I yes means do any necessary data movement
and/or replication "now"
Alternatively you can say -I defer, which will leave the files
"ill-replicated" and then fix them up with mmrestripefs later.
The -I yes vs -I defer choice is the same as for mmchattr. Think of
mmapplypolicy as a fast, parallel way to do
find ... | xargs mmchattr ...
Advert: see also samples/ilm/mmfind -- the latest version should have an
-xargs option
From: Jan-Frode Myklebust <janfrode at tanso.net>
To: gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date: 08/31/2016 04:44 PM
Subject: Re: [gpfsug-discuss] Data Replication
Sent by: gpfsug-discuss-bounces at spectrumscale.org
Assuming your DeepFlash pool is named "deep", something like the following
should work:
RULE 'deepreplicate'
migrate from pool 'deep' to pool 'deep'
replicate(2)
where MISC_ATTRIBUTES NOT LIKE '%2%' and POOL_NAME LIKE 'deep'
"mmapplypolicy gpfs0 -P replicate-policy.pol -I yes"
and possibly "mmrestripefs gpfs0 -r" afterwards.
-jf
On Wed, Aug 31, 2016 at 8:01 PM, Brian Marshall <mimarsh2 at vt.edu> wrote:
Daniel,
So here's my use case: I have a Sandisk IF150 (branded as DeepFlash
recently) with 128TB of flash acting as a "fast tier" storage pool in our
HPC scratch file system. Can I set the filesystem replication level to 1
then write a policy engine rule to send small and/or recent files to the
IF150 with a replication of 2?
Any other comments on the proposed usage strategy are helpful.
Thank you,
Brian Marshall
On Wed, Aug 31, 2016 at 10:32 AM, Daniel Kidger <daniel.kidger at uk.ibm.com>
wrote:
The other 'Exception' is when a rule is used to convert a 1 way replicated
file to 2 way, or when only one failure group is up due to HW problems. It
that case the (re-replication) is done by whatever nodes are used for the
rule or command-line, which may include an NSD server.
Daniel
IBM Spectrum Storage Software
+44 (0)7818 522266
Sent from my iPad using IBM Verse
On 30 Aug 2016, 19:53:31, mimarsh2 at vt.edu wrote:
From: mimarsh2 at vt.edu
To: gpfsug-discuss at spectrumscale.org
Cc:
Date: 30 Aug 2016 19:53:31
Subject: Re: [gpfsug-discuss] Data Replication
Thanks. This confirms the numbers that I am seeing.
Brian
On Tue, Aug 30, 2016 at 2:50 PM, Laurence Horrocks-Barlow <
laurence at qsplace.co.uk> wrote:
Its the client that does all the synchronous replication, this way the
cluster is able to scale as the clients do the leg work (so to speak).
The somewhat "exception" is if a GPFS NSD server (or client with direct
NSD) access uses a server bases protocol such as SMB, in this case the SMB
server will do the replication as the SMB client doesn't know about GPFS
or its replication; essentially the SMB server is the GPFS client.
-- Lauz
On 30 August 2016 17:03:38 CEST, Bryan Banister <bbanister at jumptrading.com
> wrote:
The NSD Client handles the replication and will, as you stated, write one
copy to one NSD (using the primary server for this NSD) and one to a
different NSD in a different GPFS failure group (using quite likely, but
not necessarily, a different NSD server that is the primary server for
this alternate NSD).
Cheers,
-Bryan
From: gpfsug-discuss-bounces at spectrumscale.org [mailto:
gpfsug-discuss-bounces at spectrumscale.org] On Behalf Of Brian Marshall
Sent: Tuesday, August 30, 2016 9:59 AM
To: gpfsug main discussion list
Subject: [gpfsug-discuss] Data Replication
All,
If I setup a filesystem to have data replication of 2 (2 copies of data),
does the data get replicated at the NSD Server or at the client? i.e.
Does the client send 2 copies over the network or does the NSD Server get
a single copy and then replicate on storage NSDs?
I couldn't find a place in the docs that talked about this specific point.
Thank you,
Brian Marshall
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