[OpenIndiana-discuss] Hitachi 4 TB disks + HP Microserver + OI 151 + ZFS

[Richard Elling]

On Apr 29, 2012, at 7:38 PM, Gordon Ross wrote:

> On Sun, Apr 29, 2012 at 8:46 PM, Richard Elling
> <richard.elling at richardelling.com> wrote:
>> 
>> On Apr 29, 2012, at 11:45 AM, George Wilson wrote:
> [...]
>>> 
>>> Speaking of 4K sectors, I've taken a slightly different approach that fixes this outside of ZFS. The idea is to allow sd to override the physical-block-size which ZFS will pick up. The way this works is you can specify the Vendor/Product id in sd.conf. Here's an example:
>>> 
>>> sd-config-list = "NETAPP  LUN, "physical-block-size:4096";
>> 
>> This is the preferred solution and there are several implementations running
>> around in various stages of test/release/acceptance. I look forward to getting this
>> upstream :-)
>>  -- richard
> 
> Providing a work-around in "sd" is great.  We should do that, at least.
> 
> But is it sufficient?  What happens if I replace a mirrored drive with
> 512 byte sectors with one having 4k sectors?  What if I want to plan
> ahead for that?  Maybe in only some of my ZFS pools but not all?
> It would seem that a pool-level override for "ashift" might also be useful.

ashift is set for the top-level vdev at creation time. So you have to override
prior to creation of the mirror.
 -- richard

--
ZFS Performance and Training
Richard.Elling at RichardElling.com
+1-760-896-4422