SSD’s are the one of the most expensive storage devices when measured by the GB but they are the least expensive when measured in terms of IOPs.
Using SSD in addition to tradition fibre channel and SATA drives can significantly improve the performance of your storage systems and bring your storage costs down.
As an example. in my own lab I have two ESX ( vSphere 4.1 ) hosts direct attached to a HP MSA1500 and I see peaks of around 10000 to 12000 KBps ( figures from Virtual Center performance tab ). I had a spare 120Gb OCZ SSD and a HP XW6200 lying around so I had my friends at Falconstor give me an eval license and I setup their NSS storage virtualization server in front of the MSA1500 with my el-cheapo SSD disk attached.
I enabled the NSS SafeCache feature which causes all writes to firstly go to the SSD and then staged to the MSA at a later date. I also enabled their Hotzone feature which looks for hotspots in the data and moves them to SSD for fast access. The performance of the ESX servers jumped to 120,000 KBps, a 10 fold increase in performance and I could see in the response times on some of the more utilised VM’s in the farm. I would suggest if you are going to do this that you get a commercial grade SSD.
At the enterprise level, including the Falconstor NSS previous mentioned, these features are also available in EMC’s V-Max and the latest EMC Clariion’s by using policies to monitor for hot spots in the data and move this heavily used data to faster storage.
Also the new IBM SVC’s ( San Volume Controllers ) are also now also supporting SSD’s in their appliance to increase performance of the storage they are front ending.
And I am sure that other vendors are also implementing this technology.
Performance based storage architecture calculations are based on the number of spindles required to get the meet a given number of IOPs. Using SSD with the above technologies these IOP numbers can be achieved with fewer spindles.
In summary, when used in conjunction with traditional fibre channel and SATA drives, SSD’s can actually save money bringing the cost of your storage down and providing great performance when its required using less hardware.