svn commit: r300207 - in head: sbin/camcontrol sys/cam/ata sys/cam/scsi sys/dev/ahci sys/geom sys/geom/eli sys/kern sys/sys usr.sbin usr.sbin/diskinfo usr.sbin/zonectl

[Adrian Chadd]

On 19 May 2016 at 07:50, Kenneth D. Merry <ken at freebsd.org> wrote:
> On Thu, May 19, 2016 at 15:30:37 +0100, Bruce Simpson wrote:
>> Right On Commander!
>>
>> Now here is hoping the random-write issues with OpenZFS are solved...
>
> Well, this is of course only the underlying infrastructure for SMR drives.
>
> As for the random write issues with ZFS (or rather sequential I/O going out
> in random order), we (Spectra) are working on that in general.
>
> The original plan was to do full SMR support for ZFS, but it looks like we
> may get good enough write performance with Drive Managed drives by just
> making writes from ZFS to drives more sequential rather than going for full
> Host Aware and Host Managed support.  If that turns out that performance
> isn't good enough after all, then we'll have to put in the effort to put
> Host Aware support at least into ZFS.
>
> That's why I said (in the commit message) that I don't know of anyone
> working on using the SMR infrastructure for UFS or ZFS.  Now that the
> plumbing is in place in CAM and GEOM, it is possible at the filesystem
> level if someone wants to do the work.

Is it possible to use this from userland for now? Ie, probe whatever
we need to in order to understand the transaction geometries (ie, the
optimal sizes for reading/writing, etc) and then issue IOs that are in
line with this?



-adrian