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

[Peter Wood]

I'm building a storage server with Dell MD1000 DAS and I just bought 30
drives with 4K sectors.

One of the reasons I selected the "new" 4K sector is so I can easily find
replacement drives 2-3 years from now when they start failing. Looks like
this was a huge mistake.

I'm fine if the drives report 512B sectors and work in slower legacy mode
as long as they work reliable but seems that this may not be the case. On
top of that my internal drives that make the rpool have 512B sectors so I'm
not sure how workarounds will effect this pool.

Is it fair to say that if one uses 4K drives he will run into alignment
issue sooner or later?

I'm really puzzled what to do here.

Should I try to replace the drives with 512B ones before the storage goes
life?

Any thoughts?

Thank you
Peter

On Mon, Apr 30, 2012 at 7:54 AM, Richard Elling <
richard.elling at richardelling.com> wrote:

> 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
>
>
>
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