[zfs-discuss] Pure SSD Pool

Fajar A. Nugraha
Tue, 12 Jul 2011 12:40:56 -0000

On Tue, Jul 12, 2011 at 6:18 PM, Jim Klimov <jimklimov at cos.ru>
wrote:
> 2011-07-12 9:06, Brandon High ?????:
>>
>> On Mon, Jul 11, 2011 at 7:03 AM, Eric Sproul<esproul at
omniti.com> ?wrote:
>>>
>>> Interesting-- what is the suspected impact of not having TRIM
support?
>>
>> There shouldn''t be much, since zfs isn''t changing
data in place. Any
>> drive with reasonable garbage collection (which is pretty much
>> everything these days) should be fine until the volume gets very full.
>
> I wonder if in this case it would be beneficial to slice i.e. 90%
> of an SSD for use in ZFS pool(s) and leave the rest of the
> disk unassigned to any partition or slice? This would reserve
> some sectors as never-written-to-by-OS. Would this ease the
> life for SSD devices without TRIM between them ans the OS?

Possibly so. That is, assuming your SSD has a controller (e.g.
sandforce-based) that''s able to do some kind of wear-leveling. They
maximize the number of unused sector by using compression, dedup, and
reserving some space internally, but if you keep some space ununsed it
should add up the number of "free" sectors (thus enabling it to
rewrite the same sector less often, prolonging the disk lifetime).

--
Fajar