[postgis-users] VMWare and PostGIS

[Stephen V. Mather]

> What's going to kill your DB performance in both cases is iSCSI in
> general.  Even though iSCSI might provide a lot of bandwidth for large
> sequential I/O with selected hardware, the performance for small as
> well as random I/O is quite bad, simply because it adds a huge amount
> of latency.  By running a couple of benchmarks on bare-iron VMware I
> was able to prove that access to *local* disks, even through storage
> virtualization, outperformed any of the iSCSI setups by at least four ! 
> times the numbers of reads/writes as well as bare bandwidth.
> 
> Thus, the iSCSI penalty stems from the fact that every I/O block gains
> latency by passing two full TCP/IP stacks (plus multiple block device
> abstraction layers) and it doesn't matter much wether it's the IP stack
> on the host or the one in the guest.

Ah, so a SAN may not be the best option either.  Well, we're narrowing the options down... .

Thanks,
Best,
Steve