Perhaps the most striking thing about the test results is that local and iSCSI rates are virtually identical, both for Windows and Linux. Truly, there's no performance penalty for using the ReadyNAS as an iSCSI datastore. In fact, with the benefits iSCSI delivers, such as vMotion support, there's no reason not to move to shared storage.
As expected in filesystem testing, reread and rewrite operations are faster than initial reads and writes. That's because filesystems cache information for reuse.
What's more surprising is that I/O rates are relatively low at best, around 2.5GBps for a local Linux server doing rereads. Since local and iSCSI rates are quite similar, ReadyNAS clearly isn't the bottleneck.
A more likely culprit is the amount of data each virtual machine can read at a time. The IOzone results presented here are the averages of all results for file sizes ranging from 64K to 4GB, and rates fall off sharply for file sizes of 8MB and larger. (In fact, when we looked only at file sizes of 4MB and smaller, overall average rates nearly doubled, to a maximum of nearly 5GBps.) This shouldn't be taken as a knock on the ReadyNAS, but rather an indication that virtual machine setup parameters can have an effect on I/O performance.
With its combination of simple setup, easy management and good performance, we found the ReadyNAS 3100 to be a competent and capable NAS device. For small and mid-sized organizations looking to get into shared storage, this is a great place to start
Sign up for Computerworld eNewsletters.