The HP Smart Array P410 is a fine controller, but you will get poor performance out of it if you don't have the battery-backed or flash-backed cache units installed. The cache makes a tremendous difference in that writes are buffered by the cache memory before being committed to disk. You get the write confirmation to the application without having to incur the latency of the physical disk drives.
Here's a 4GB dd on a similarly-spec'd system (DL380 G7 with 24GB RAM and a p410 with 2 x SAS disks and 1GB Flash-Backed Write Cache). The RAM helps a lot in a test like this, but you get the idea...
[root@xxxx /]# dd if=/dev/zero of=somefile bs=1M count=4096
4096+0 records in
4096+0 records out
4294967296 bytes (4.3 GB) copied, 3.70558 seconds, 1.2 GB/s
But realistically, your write performance with two SAS drives in a RAID 1 on that controller with the appropriate cache should be between a sustained 130-170 megabytes/second. A quick iozone
test on the above server configuration shows:
[root@xxxx /]# iozone -t1 -i0 -i1 -r1m -s16g
Write
Avg throughput per process = 166499.47 KB/sec
Rewrite:
Avg throughput per process = 177147.75 KB/sec
Since you're using ESXi, you can't run online firmware updates. You should download the Current Smart Update Firmware DVD, burn it to disk and make sure your system is patched to a relatively recent level.
Here are the controller's quickspecs:
http://h18004.www1.hp.com/products/quickspecs/13201_na/13201_na.html
You will want to purchase one of the following, ranging from $350-$600 US:
512MB BBWC
512MB Flash Backed Write Cache
1G Flash Backed Write Cache
To answer your question, the cache solution will help the most. Additional disks won't make much of a difference until you handle the caching situation.
*Note for other users. If you have cache memory on recent HP controllers with up-to-date firmware, there is a write cache override available if you have RAM on the controller but no battery unit. It's slightly risky, but can be an intermediate step in testing what performance would be like on the way to buying a battery or flash unit.
A few things... I'm assuming this is a 64-bit edition of Windows Server 2003 and that your storage setup is a RAID 1 with online spare. Is there any chance Windows 2008 would manage resources better? This seems to be more of an application profiling problem. Are you assuming that using SSDs will help pagefile performance? Do you have any evidence that that's a bottleneck? How are things performing now? Why not try moving the pagefiles to a lower-cost SATA SSD to test the theory before jumping into enterprise SSD drives?
As to your question about the HP-branded SSD drives, the OEM is Sandisk/Pliant. These drives are extremely overpriced at the moment. To be honest, these disks require a deep queue in order to perform well. They fall short in performance in many of my applications. I would recommend a different drive for your application if you're concerned about the cost of the part number you noted. The best performance will come from a STEC-branded SSD, but at an even higher cost. A nice alternative that would run well under a variety of conditions is the Seagate Pulsar SAS SSD offering. The Pulsar.2 in 200GB is a great MLC drive that would come in at half the cost of the HP/Pliant disk.
Other notes... This server has an HP SmartArray P400 controller. It's only a 3G SAS controller. You may want to consider using a 6G-capable controller like the HP SmartArray P410 if you do end up using enterprise SSD drives. Also, do you have a battery-backed RAID cache on the existing controller?
Also, why replace the OS drives? You can add another logical drive comprised of the new disks.
Best Answer
The answer here depends on the specific model of server being used. I was holding off until the OP could describe the actual server being used, as the SSD options vary.
Read through the descriptions of HP's SSD portfolio for detailed information on the different classes of drive.
For instance, with a G6 or G7 ProLiant, all SSD performance will be controller-limited. SATA SSDs will downshift to 3Gbps speeds, and the controller will max out at ~20,000 IOPS. However, many third-party SAS SSDs will be incompatible, with the exception of the HP SAS SSDs. The HP Enterprise SAS SSDs are OEM by Sandisk/Pliant, and aren't terribly good performers. They have deep I/O queues and require a certain I/O profile to really perform well. They have great endurance, though.
With a Gen8 ProLiant, third party SSDs (like the Samsung) are not an option. They will at best, trigger a POST alert (Error 1709), or at worst, won't be recognized or cause temperature sensor issues. The non-enterprise SSD offerings by HP are either Intel, Samsung or STEC (MachIOPS) OEM. The Enterprise are Sandisk. All have HP firmware and are authenticated for use with Gen8 systems.
The specific drive you're curious about (691862-B21) is an Intel or Samsung drive. It's a read-optimized disk that's good for caching duties, but a low-performing write SSD. I've had clients return these as they were disappointed at the performance profile and that their array of spinning disks was more capable from a throughput perspective.
Please also see: Third-party SSD solutions in ProLiant Gen8 servers