[lustre-discuss] zfs -- mds/mdt -- ssd model / type recommendation

[Andrew Holway]

ZFS should not be slower for very long. I understand that, now ZFS on Linux
is stable, many significant performance problems have been identified and
are being worked on.

On 5 May 2015 at 04:20, Andrew Wagner <andrew.wagner at ssec.wisc.edu> wrote:

> I can offer some guidance on our experiences with ZFS Lustre MDTs. Patrick
> and Charlie are right - you will get less performance per $ out of ZFS MDTs
> vs. LDISKFS MDTs. That said, our RAID10 with 4x Dell Mixed Use Enterprise
> SSDs achieves similar performance to most of our LDISKFS MDTs. Our MDS was
> a Dell server and we wanted complete support coverage.
>
> One of the most important things for good performance with our ZFS MDS was
> RAM. We doubled the amount of RAM in the system after experiencing
> performance issues that were clearly memory pressure related. If you expect
> to have tens of millions of files, I wouldn't run the MDS without at least
> 128GB of RAM. I would be prepared to increase that number if you run into
> RAM bottlenecks - we ended up going to 256GB in the end.
>
> For a single OSS, you may not need 4x SSDs to deal with the load. We use
> the 4 disk RAID10 setup with a 1PB filesystem and 1.8PB filesystem. Our use
> case was more for archive purposes, so we wanted to go with a complete ZFS
> solution.
>
>
>
> On 5/4/2015 1:18 PM, Kevin Abbey wrote:
>
>> Hi,
>>
>>  For a single node OSS I'm planning to use a combined MGS/MDS. Can anyone
>> recommend an enterprise ssd designed for this workload?  I'd like to create
>> a raid10  with 4x ssd using zfs as the backing fs.
>>
>> Are there any published/documented systems using zfs in raid 10 using ssd?
>>
>> Thanks,
>> Kevin
>>
>>
>>
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