[zfs-discuss] Pure SSD Pool

Eric Sproul
Tue, 12 Jul 2011 19:14:11 -0000

On Tue, Jul 12, 2011 at 1:35 PM, Brandon High <bhigh at freaks.com>
wrote:
> Most "enterprise" SSDs use something like 30% for spare area. So
a
> drive with 128MiB (base 2) of flash will have 100MB (base 10) of
> available storage. A consumer level drive will have ~ 6% spare, or
> 128MiB of flash and 128MB of available storage. Some drives have 120MB
> available, but still have 128 MiB of flash and therefore slightly more
> spare area. Controllers like the Sandforce that do some dedup can give
> you even more effective spare area, depending on the type of data.

I see, thanks for that explanation.  So finding drives that keep more
space in reserve is key to getting consistent performance under ZFS.

Eric