Bryan Murphy wrote:
Our database server connects to the san via iSCSI over Gig/E using jumbo frames. File system is XFS (noatime).
...
Throughput, however, kinda sucks. I just can't get the kind of throughput to it I was hoping to get. When our memory cache is blown, the database can be downright painful for the next few minutes as everything gets paged back into the cache.
Remember that Gig/E is bandwidth limited to about 100 Mbyte/sec. Maybe a little faster than that downhill with a tailwind, but not much. You're going to get much better bandwidth connecting to a local raid card talking to local disks simply due to not having the ethernet as a bottleneck. iSCSI is easy to set up and manage, but it's slow. This is the big advantage Fibre Channel has- serious performance. You can have multiple channels on a single fibre channel card- IIRC, QLogic's cards have a default of 4 channels- each pumping 400 Mbyte/sec. At which point the local bus rapidly becomes the bottleneck. Of course, this comes at the cost of a signifigant increase in complexity.
Brian ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
