On Thu, Mar 17, 2011 at 5:47 PM, steve <st...@lonetwin.net> wrote: > This is a very interesting approach. Going beyond periodic syncing, one of the > things I've been planning to try out (although never got around doing) is to > setup my dev environment (ie: app server including the db) on a ramdisk, which > is disk backed up as part of a raid to a loopback mounted disk image :) ! > ...this is something suggested by someone on IRC -- not sure of the practical > benefits, but it sounds like a nice idea.
Clever, but it's a terrible idea in terms of performance. RAID1 assumes both your disks have similar performance. The RAID1 driver will ack disk writes only after both disks in the raid group successfully commit data. So your write performance is still the same as that of your HDD. However, if your IO pattern is primarily reads, you should experience better than HDD performance. Since your RAM disk is volatile, your RAID1 array will be in degraded mode on boot up. You need to handle this case manually. > I'll try to get it done this weekend. Instead of a loopback mount, suggest you use LVM or a raw block device. That way you minimize the number of layers you need to go through to disk. Do let us know the outcome. I would love to be proved wrong ;-) Btw, there are vendors who retail RAM "disk arrays", eg. ramsan.com. Works really well for apps high performance apps which do not support memcached. - Raja _______________________________________________ ILUGC Mailing List: http://www.ae.iitm.ac.in/mailman/listinfo/ilugc
