Re: The old raw devices chestnut.

Jim Smith <jim@jimsmith.demon.co.uk> wrote in news:dS4PuczgskeAFwJq@jimsmith.demon.co.uk: > Sybase: (some experience) > Sybase claim filesystems are faster, because of OS buffering, but > unsafe for the same reason. They only ever suggest filesystem for > tempdb. They don't seem to have heard of fsync()[1] Your data on Sybase ASE is dated. Sybase allows you to use buffered devices and you can elect to have the writes posted (DSYNC=on) or buffered (DSYNC=off). Sybase has always recommended one uses raw devices. For all DB's, I always use raw devices based on the benchmark numbers I've run and intuitively, it makes sense. If you have a read-mostly table, you may gain from utilizing OS buffering with a 32-bit DB and more than 4G of main memory on the box. (I'm over simplifying however not too much). A benchmarking trick I learned from one of the team members was to use symlinks to my raw devices. If I needed to add more disks to a particular volume, I could down the DBMS, dd the data out to another disk, rebuild the volume, dd the data back, start the DBMS. Voila! Regards, -- Pablo Sanchez - Blueoak Database Engineering, Inc http://www.blueoakdb.com