AIX

Actually this is not really true. SAN may be faster than single disks, but you can create all sorts of striped disksets (RAIDs of various sorts), flash disks and caching controllers to achieve the same speed and throughput for a considerably lower price.

This is not to say that SAN is a bad idea in and of itself, but your setup seems to be intent not to use the advantages of a SAN anyway.

I hope this helps.

bakunin

I don't see why it would not work, however you are then limiting yourself for future growth. If you p-Series has two fibre cards and you have two free HBA on the SAN then you should just be able to cable them, but if you want to add another server, you have to make a choice:-What is your likely future growth? If you are sure there is no growth then go ahead, but if you think you might replace your server at some point and might like to migrate the LUNs across, then you either have to have enough spare HBAs or invest in switches early is my recommendation.


Thinking about IO speed, it seems to be the write requests that work better. With local disk (not including hardware raid) the OS is directly responsible for ensuring that the write has been committed to the brown-spinning-stuff and must wait to get it done. With hardware RAID and SAN disk, you normally get a big chunk of cache. The OS writes to this cache and gets an acknowledgement that the write is complete. The server can then carry on and the disk array then completes the true write to the brown-spinning-stuff in it's own time to best economy based on physical head positions and rotation position of the disks.


I hope that this helps,
Robin