On 12/04/13 15:43, Bob Cregan wrote:
Hi Orlando,
We use ctdb/samba for CIFS, and CNFS for NFS
(GPFS version 3.4.0-13) . Current versions are
ctdb - 1.0.99
samba 3.5.15
Both compiled from source. We have about 300+ users normally.
We have suspicions that 3.6 has put additional "chatter" into the ctdb
database stream, which has pushed us over the edge. Barry Evans has
found that the clustered locking databases, in particular, prove to be a
scalability/usability limit for ctdb.
We have had no issues with this setup apart from CNFS which had 2 or 3
bad moments over the last year . These have gone away since we have
fixed a bug with our 10G NIC drivers (emulex cards , kernel module
be2net) which lead to occasional dropped packets for jumbo frames. There
have been no issues with samba/ctdb
The only comment I can make is that during initial investigations into
an upgrade of samba to 3.6.x we discovered that the 3.6 code would not
compile against ctdb 1.0.99 (compilation requires tthe ctdb source )
with error messages like:
configure: checking whether cluster support is available
checking for ctdb.h... yes
checking for ctdb_private.h... yes
checking for CTDB_CONTROL_TRANS3_COMMIT declaration... yes
checking for CTDB_CONTROL_SCHEDULE_FOR_DELETION declaration... no
configure: error: "cluster support not available: support for
SCHEDULE_FOR_DELETION control missing"
What occurs to me is that this message seems to indicate that it is
possible to run a ctdb version that is incompatible with samba 3.6.
That would imply that an upgrade to a higher version of ctdb might
help, of course it might not and make backing out harder.
Certainly 1.0.114 builds fine - I've not tried 2.0, I'm too scared! The
versioning in CTDB has proved hard for me to fathom...
A compile against ctdb 2.0 works fine. We will soon be running in this
upgrade, but I'm waiting to see what the samba people say at the UG
meeting first!
It has to be said - the timing is good!
Cheers,
Orlando
Thanks
Bob
On 12 April 2013 13:37, Orlando Richards <[email protected]
<mailto:[email protected]>> wrote:
Hi folks, ac <mailto:[email protected]>
We've long been using CTDB and Samba for our NAS service, servicing
~500 users. We've been suffering from some problems with the CTDB
performance over the last few weeks, likely triggered either by an
upgrade of samba from 3.5 to 3.6 (and enabling of SMB2 as a result),
or possibly by additional users coming on with a new workload.
We run CTDB 1.0.114.4-1 (from sernet) and samba3-3.6.12-44 (again,
from sernet). Before we roll back, we'd like to make sure we can't
fix the problem and stick with Samba 3.6 (and we don't even know
that a roll back would fix the issue).
The symptoms are a complete freeze of the service for CIFS users for
10-60 seconds, and on the servers a corresponding spawning of large
numbers of CTDB processes, which seem to be created in a "big bang",
and then do what they do and exit in the subsequent 10-60 seconds.
We also serve up NFS from the same ctdb-managed frontends, and GPFS
from the cluster - and these are both fine throughout.
This was happening 5-10 times per hour, not at exact intervals
though. When we added a third node to the CTDB cluster, it "got
worse", and when we dropped the CTDB cluster down to a single node
and everything started behaving fine - which is where we are now.
So, I've got a bunch of questions!
- does anyone know why ctdb would be spawning these processes, and
if there's anything we can do to stop it needing to do it?
- has anyone done any more general performance / config
optimisation of CTDB?
And - more generally - does anyone else actually use ctdb/samba/gpfs
on the scale of ~500 users or higher? If so - how do you find it?
--
--
Dr Orlando Richards
Information Services
IT Infrastructure Division
Unix Section
Tel: 0131 650 4994
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
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--
Bob Cregan
Senior Storage Systems Administrator
ACRC
Bristol University
Tel: +44 (0) 117 331 4406
skype: bobcregan
Mobile: +44 (0) 7712388129
--
--
Dr Orlando Richards
Information Services
IT Infrastructure Division
Unix Section
Tel: 0131 650 4994
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.
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