Re: Exadata backups
Date: Mon, 28 Oct 2013 15:57:30 -0700 (PDT)
Message-ID: <1383001050.52646.YahooMailNeo_at_web164001.mail.gq1.yahoo.com>
Thanks Alan. So you are saying that the ZFS appliance will read the files directly from the cell server and not use any CPU cycles on the compute node? I am interested to know more about how that works, there are a couple of things that I expect to be true, that must not be for this to work. - Things like the RMAN job is kicked off from the compute node, assuming this is true somehow the cell server and appliance need to be able to speak directly, how is this done? I thought this might be where NDMP comes in. - I am pretty sure Oracle said do not install software on the cell nodes, so if the cell server and the appliance need to speak I would expect something tho be installed for this to work. Anything you have to explain the architecture for this is appreciated, I am willing to RTFM, I just can't find TFM to R.
Thanks,
Mike
On Monday, October 28, 2013 5:41 PM, Guillermo Alan Bort <cicciuxdba_at_gmail.com> wrote:
If you have a ZFS appliance, then the RMAN backup can actually be offloaded to the storage cells. That alone make exadata + zfs a LOT better than exadata + DD.
I've worked a couple of times with DD, but only over ethernet, and I was not impressed by the performance and there were a lot of limitations regarding number of channels and such. We also had some issues with NFS, but I think that was lack of knowledge on our part and not a limitation of the product itself. Still, it took a while to get it right with DD.
I was deeply impressed by the speed of both RMAN backups and datapump operations to zfs, I reckon this can be accounted for by the InfiniBand network, and if you connect datadomain over infiniband you may get similar results, with the exception of offloading backup operations to the storage cells.
Just to clarify, I've never tried a DD connected to Exadata.
From the DBA point of view, it makes little difference, Exadata is so fast and has so many nice QoS features (IORM for one) that you can take backups even during daytime and still have little to no effect on the application workload (especially OLTP). The only performance difference may be seen because with ZFS you can offload backup and restore opration to the cell and with datadomain you can't, which means the database server will have to process the entire database.
The other issue to consider is whether you want to back up only databases residing in the Exadata or if you want to use the backup appliance for other things. In the latter scneario I would go with DD.
Alan.-
On Mon, Oct 28, 2013 at 3:40 PM, hansie <hansrajsao_at_gmail.com> wrote:
Mike
>
>RMAN is only option for Exadata databases backups irrespective of Oracle
>ZFS or EMC DD. So backup happens from compute node only. unless you are
>using DataGuard and taking backup from there. EMC DD is better option for
>sure.
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>Thanks
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>Hansraj
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>On Mon, Oct 28, 2013 at 1:42 PM, mike boligan <mboligan_at_yahoo.com> wrote:
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>> We are implementing Exadata and are in the process of evaluating backup
>> appliances. We are looking at the Oracle ZFS solution and the EMC
>> Datadomain solution. Anyone go through a similar evaluation recently?
>> Our storage folks seem to be leaning towards EMC because it has more
>> administrative features (for things like replicating to a DR site).
>>
>> I remember hearing our ACS person mention that the ZFS appliance will
>> backup Exadata databases going only through the storage cell and not the
>> compute node. I tried to find something to verify this but am unable to.
>> If true, this would make this decision pretty easy, if you can confirm or
>> deny this as well I would appreciate that.
>>
>> TIA,
>> Mike
>> --
>> http://www.freelists.org/webpage/oracle-l
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>Thanks,
>Hansraj
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>http://www.freelists.org/webpage/oracle-l
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-- http://www.freelists.org/webpage/oracle-lReceived on Mon Oct 28 2013 - 23:57:30 CET