[zfs-discuss] Advice: letting your pool zzzzzleep

Manuel Amador (Rudd-O) rudd-o at rudd-o.com
Wed Dec 7 16:52:31 EST 2011


You mean all writes to the LOG device, right?  ;-)

This option would only be useful if the log device is faster than the
disks, or if ZFS somehow could know that the backing disks are sleeping.
Otherwise, it would ruin performance to add, say, a USB pen drive log
device. 

ATM the intended purpose of the log device is solely this: flush small
but numerous POSIX sync operations.

On Wed, 2011-12-07 at 13:46 -0800, Christ Schlacta wrote:
> this reminds me.  I wanted to feature request something:
> Can we add a mode that forces zfs to send all writes to the cache device 
> until it's full.
> 
> Additional, but separate is an option to refuse to spin up disks for 
> read or write, and instead return a sensible error.
> 
> I ask because I want to use zfs to back a logging and video recoding 
> server, and I believe these changes would allow me to maximize recording 
> time in the event of a power outtage, by allowing me to spin down 
> non-essential disks and stop extra services, but writing to cache device 
> until it's full, then optionally (configurable?) flushing to disk all at 
> once while the UPS is working.
> 
> On 12/7/2011 13:37, Manuel Amador (Rudd-O) wrote:
> > http://rudd-o.com/en/linux-and-free-software/tip-letting-your-zfs-pool-sleep
> >
> > Enjoy!
> >
> 




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