On 20 Oct 2011, at 05:24, Dennis Glatting <free...@penx.com> wrote:

> On Thu, 20 Oct 2011, Fajar A. Nugraha wrote:
>> On Thu, Oct 20, 2011 at 7:56 AM, Dave Pooser <dave....@alfordmedia.com> 
>> wrote:
>>> On 10/19/11 9:14 AM, "Albert Shih" <albert.s...@obspm.fr> wrote:
>>>> When we buy a MD1200 we need a RAID PERC H800 card on the server
>>> No, you need a card that includes 2 external x4 SFF8088 SAS connectors.
>>> I'd recommend an LSI SAS 9200-8e HBA flashed with the IT firmware-- then
>>> it presents the individual disks and ZFS can handle redundancy and
>>> recovery.
>> Exactly, thanks for suggesting an exact controller model that can
>> present disks as JBOD.
>> With hardware RAID, you'd pretty much rely on the controller to behave 
>> nicely, which is why I suggested to simply create one big volume for zfs to 
>> use (so you pretty much only use features like snapshot, clones, etc, but 
>> don't use zfs self healing feature). Again, others might (and have) disagree 
>> and suggest using volumes for individual disk (even when you're still 
>> relying on hardware RAID controller). But ultimately there's no question 
>> that the best possible setup would be to present the disks as JBOD and let 
>> zfs handle it directly.
> I saw something interesting and different today, which I'll just throw out.
> A buddy has a HP370 loaded with disks (not the only machine that provides 
> these services, rather the one he was showing off). The 370's disks are 
> managed by the underlying hardware RAID controller, which he built as 
> multiple RAID1 volumes.
> ESXi 5.0 is loaded and in control of the volumes, some of which are 
> partitioned. Consequently, his result is vendor supported interfaces between 
> disks, RAID controller, ESXi, and managing/reporting software.
> The HP370 has multiple FreeNAS instances whose "disks" are the "disks" 
> (volumes/partitions) from ESXi (all on the same physical hardware). The 
> FreeNAS instances are partitioned according to their physical and logical 
> function within the infrastructure, whether by physical or logical 
> connections. The FreeNAS instances then serves its "disks" to consumers.
> We have not done any performance testing. Generally, his NAS consumers are 
> not I/O pigs though we want the best performance possible (some consumers are 
> over the WAN resulting in any HP/ESXi/FreeNAS performance issues possibly 
> moot). (I want to do some performance testing because, well, it may have 
> significant amusement value.) A question we have is whether ZFS (ARC, maybe 
> L2ARC) within FreeNAS is possible or would provide any value.

Possible, yes.
Provides value, somewhat.

You still get to use snapshots, compression, dedup...
You don't get ZFS self healing though which IMO is a big loss.

Regarding the ARC, it totally depends on the kind of files you serve and the 
amount of RAM you have available.

If you keep serving huge, different files all the time, it won't help as much 
as when clients request the same small/avg files over and over again.
zfs-discuss mailing list

Reply via email to