Veritas vxfs filesystem performance
In an attempt to use the direct I/O feature of Sybase ASE 15 on a Veritas filesystem I ran into a couple of issues. It seems that direct i/o is not possible on this type of filesystem. You will see this in the errorlog:
Unable to open file in DIRECTIO_ON mode, error: (25) Inappropriate ioctl for device
To get the best performance out of this type of filesystem I ran some tests with different mount options.
A normal mount has these options set: read/write/nosuid/delaylog/largefiles/ioerror=mwdisable Additional mount options used in the test were: mincache=direct and convosync=direct
See below graphs for a quick overview of the resulting throughput. For each bar the specific Sybase device settings are given (dsync / directio), as well as the Vertitas mount options. A higher bar means better throughput.