If I/O performance is a concern, you may be interested in ZFS and Flashcache.
Specifically, ZFS' ZIL (ZFS Intent Log) and its L2ARC (Layer 2 Adaptive Read Cache) ZFS does run on Linux http://zfs-fuse.net
Flashcache: https://github.com/facebook/flashcache/
Both of these techniques can use a pair of SSDs in RAID1 rather than a single SSD.
On Oct 27, 2011, at 1:31 AM, Ed W wrote:
On 27/10/2011 03:36, Stan Hoeppner wrote:
Hi all,
is anyone on this list who dares/dared to store his index files on a MLC-SSD? I have not. But I can tell you that a 32GB Corsair MLC SSD in my workstation died after 4 months of laughably light duty. It had nothing to do with cell life but low product quality. This was my first foray into SSD. The RMA replacement is still kickin after 2 months,
On 10/26/2011 4:13 PM, Patrick Westenberg wrote: thankfully. I'm holding my breath...
Scanning the reviews on Newegg shows early MLC SSD failures across most brands, early being a year or less. Some models/sizes are worse than others. OCZ has a good reputation overall, but reviews show some of their models to be grenades.
Thus, if you were to put indexes on SSD, you should strongly consider using a mirrored pair.
I don't think you are saying that the advice varies here compared with HDDs? I do agree that some SSDs are showing very early failures, but it's only a tweak to the probability parameter compared with any other storage medium. They ALL fail at some point, and generally well within the life of the rest of the server. Some kind of failure planning is necessary
Caveat the potentially higher failures vs HDDs I don't see any reason why an SSD shouldn't work well? (even more so if you are using maildir where indexes can be regenerated).
More interestingly: for small sizes like 32GB, has anyone played with the "compressed ram with backing store" thing in newer kernels (that I forget the name of now). I think it's been marketed for swap files, but assuming I got the theory it could be used as a ram drive with slow writeback to permanent storage?
Good luck
Ed W