Eric Sandeen wrote:
Ric Wheeler wrote:
Andi Kleen wrote:
On Mon, Apr 21, 2008 at 12:42:42AM +0100, Jamie Lokier wrote:
Andi Kleen wrote:
[LVM] always disables barriers if you don't apply a so far unmerged
patch that enables them in some special circumstances (only single
backing device)
(I continue to be surprised at the un-safety of Linux fsync)
Note barrier less does not necessarily always mean unsafe fsync,
it just often means that.
Also surprisingly lot more syncs or write cache off tend to lower the MTBF
of your disk significantly, so "unsafer" fsync might actually be more safe
for your unbackuped data.
Hi Andi,
Where did you get this data?
I have never heard that using more barrier operations lowers the reliability or
the MTBF of a drive and I look at a fairly huge population when doing this ;-)
Ric, what about the other part - turning write cache off? I've also
heard it suggested that this might hurt drive lifespan, and it sorta
makes sense, I assume it keeps the head working harder...
-Eric
Turning the drive write cache off is the default case for most RAID products
(including our mid and high end arrays).
I have not seen an issue with drives wearing out with either setting (cache
disabled or enabled with barriers).
The theory does make some sense, but does not map into my experience ;-)
ric
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
