UFS2 and SSDs

[Ivan Voras]

Thomas Hurst wrote:
> * Kip Macy (kmacy at freebsd.org) wrote:
> 
>> I accidentally bought a camera-grade SSD. Random write performance
>> with UFS made it unusable. I ended up converting /usr to ZFS - since
>> which time I've been very happy with performance.
> 
> Did you try gjournal on it?  SSD's should do better with sequential
> journal writes.

My guess is that it won't matter - the issue is "small writes" not
"sequential writes". Gjournal will issue writes as it receives them - if
it receives a bunch of small ones, it will pass them on in the same
form, only sequential (the drive will still see a bunch of small
writes). This works well for mechanical drives because of rotational
properties but does nothing to SSDs.

ZFS OTOH does a great deal of buffering.

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