Microsoft Exchange 2010’s large mailboxes and low IOPS per mailbox makes SATA HDD a good fit for Exchange 2010 mailbox server storage.
Recently, there are some interests in using SSDs (Solid State Disk) with Exchange 2010 in the marketplace. Just do a search of “exchange 2010 ssd”, and you will find a number of hits.
SSD is well known for its fast IO speed, high cost and low capacity. On paper, this looks like the opposite of what Exchange 2010 needs. So, why the interests?
First of all, SSD prices continue to fall. And during 2012, the cost per GB of SSD has dropped below $1, according to the Tech Report. This makes SSDs more affordable and no doubt will boost the adoption of SDDs. Don’t get me wrong, the prices of SSDs are still much higher in comparison to that of HDDs. However, SSD’s dramatic price decrease over the last year made it more attractive.
Secondly, it is true that SSD capacities are still very small, comparing to that of HDDs. It is also true that Exchange 2010’s mailbox sizes are quite large, in the order of 1GB to 10GB. However, it is important to realize that not all data within a user’s mailbox has the same usage pattern. For example, a typical Exchange 2010 user may keep 2-year’s worth of emails inside the mailbox. But only emails of the three most recent months get heavily used (read, referenced, replied, forwarded, etc.) In other words, frequently used data inside a mailbox is only about 12.5% of the total mailbox size.
So, quite naturally, a good use of SSD with Exchange 2010 is to put most recent emails on faster, more expensive and smaller SSDs and older emails on slower, cheaper and larger HDDs, preferably SATA drives.