[sheepdog] [sheepdog-users] Sheepdog 0.6.0 schedule and todos

[Liu Yuan]

On 11/06/2012 04:10 PM, Alexandre DERUMIER wrote:
> One thing that could be great with journal, is something like slog
> device with zfs or nvram with netapp san.
> 

Currently I am writing it. To be honest, I have no idea of zfs and
netapp san.

The idea is that we log ahead all the updates of object in another
device (be it a HHD or SSD or nvram) sequentially and use buffered
IO/direct IO for actual data updates without 'O_DSYNC' flag.

I got 80x times faster even with another HDD as journal device on my test.

See more info at
http://lists.wpkg.org/pipermail/sheepdog/2012-November/007136.html

> random writes are going to a fast journal (ssd, nvram,...) then are
> flushed sequentially each X seconds to slower disks.
> 

The log write will currently is with O_DSYNC | O_DIRECT flag to assure
data integrity. I will consider group commit to accelerate log write
later when basic function is stable.

Thanks,
Yuan