ZFS on a single disk?

[Tom Evans]

On Fri, Mar 4, 2011 at 12:01 PM, Dr Josef Karthauser <joe at tao.org.uk> wrote:
> On 2 Mar 2011, at 12:16, Jeremy Chadwick wrote:
>
>> On Wed, Mar 02, 2011 at 10:28:50AM +0000, Dr Josef Karthauser wrote:
>>>
>>> I guess I should have been a bit clearer, I mean without any external
>>> devices backing them. Seeing as this is to be running on a VPS/Xen at
>>> a hosting environment I'm not able to add any additional devices. I'm
>>> not memory starved however. Is it madness to use a memory disk? (The
>>> instance in question will have 6gb of ram total to play with.).
>>
>> Again: don't disable the ZIL, and adjust the ARC to whatever size you
>> want using a combo of vm.kmem_size and vfs.zfs.arc_max.  Make use of the
>> RAM you have available to you.  :-)
>>
>
> Ok. That sounds like a plan.
>
> Next question, if I may. It looks like a XENHVM environment is unavailable
> to me, so I'm going have to stick with i386, and PAE to make the additional
> memory available. Given this constraint, does it still make sense to be
> trying to use ZFS? I had imagined that with 6GB to play with, I could
> dedicate 2GB of kernel space to the ZFS, leaving most of the rest for user
> land to play with. I've never played with PAE so I don't know whether I'm
> making any stupid assumptions here.
>
> Could I be, or is this still a sensible configuration to be thinking about?
>
> The grand picture is something like this then:
>
> - Hardware environment: XEN with 6GB ram, ample processor, 80GB disk.
> - O/S environment: FreeBSD 8.2 + PAE + XEN_PV + ZFS.
> - Goal: Host a number of ZFS managed jails in a secure and reliable way.
>
> Am I asking for trouble, or am I on the money?
>
> Joe
>
> p.s. there are some HVM XEN hosts out there, but it looks like they're all
> _much_ more expensive that the hosting provider that I'm considering, which
> appears to be offering a sweet spot of memory/cost.

PAE? What is this, the 90s? ;)

i386 + ZFS is not a wise move IMO. Any reason why you cannot use amd64?

Cheers

Tom