Mindaugas Riauba wrote:
NetApp support is claiming that such performance is normal. Somehow I do not believe that 2007 model should deliver such XXth century performance levels. :)
How many disks, what RPM are they running at, what I/O block size is being used and what protocol (NFS/iSCSI/FC) is being used?
Checking an Oracle DB I used to run it averages 7k I/Os with spikes to 59k. For a 10k RPM disk, 7k I/O size means roughly 800kBytes/second before latency starts to become an issue depending on the controller type. Really high end controllers can go up to about 1,312kB instead of 800kB. The array reports Oracle is using an average of 985 kBytes/second with spikes to 28MBytes/second.
A MySQL DB I used to run averages 41k I/Os with spikes up to 333k. For a 10k RPM disk 41k I/O is 4500 kBytes/second. The array reports MySQL using an average of 3200 kBytes/second with spikes to 34.1MBytes/second.
The array throughput numbers include benefit from the disk cache, while the raw spindle performance assumes no cache (or "worst case" performance).
Both of those are connected via Fiber channel so performance will be quite a bit higher than that of NFS or iSCSI.
So the numbers your seeing could be perfectly reasonable as NetApp suggests depending on what the exact workload is and your array configuration. For the workload you should look to the array for statistics, I'm not too familiar with NetApp arrays but I assume they offer a wide range of statistics, hopefully I/O size is among them as that is the most critical to determine throughput.
The array running the above databases is a system running 40 10k RPM disks with the data evenly distributed across all spindles for max performance. The array also is host to about 25 other systems as well.
NetApps certainly aren't the fastest thing in the west but given your performance levels it sounds like you don't have many disks connected and are limited by the disks rather than the controller(s).
Most low end arrays don't offer the level of visibility that the enterprise ones do.
On that note I'm getting a new 150TB array in today, pretty excited about that. 3PAR T400 virtualized storage system.
nate