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NOTE OF DECEMBER 9: THIS IS BEING REVISED PER READER FEEDBACK. WE UNDERESTIMATED THE NEED FOR THE USE OF EXPENSIVE STORAGE. FURTHER INPUT WELCOMED
Concern is sometimes expressed about the cost of Exchange 2010 storage:
- Users will have large mailboxes. 5GB to 20GB will be common. Take 10GB as a typical figure, allowing for three years of mailbox growth
- Then factor in some multiplier, perhaps 3 or 4, to account for the optional features of Database Availability Group. The multiplier could be much larger, but most organizations won’t go for maximal bloat
- So the average storage will commonly be around 30GB per mailbox
In short, user mailboxes are set to get substantially larger.
This will translate to many administrative challenges, but cost is unlikely to be one. At today’s prices, 30GB costs from $2 to $30, depending on the storage type. Amortize that over three years, makes $0.66 to $10 per mailbox per year. $10 is an absolute maximum, most storage will cost much less than this. Some of this storage will replace local storage used to keep PSTs. Looked at on a per-user basis, the cost of storage for Exchange 2010 are trivial.
Actually, I think that both Alan and David are correct, though both are missing the point viz Exchange 2010.
Prior to Exchange 2007, Exchange was both incredibly disk I/O intensive and I/O order sensitive. This forced data centers to make use of:
a. Very high performance (SCSI direct attached) storage, or
b. Very high performance (Fiber channel attached) Storage Area Networks (SANs)
Since Exchange, prior to Exchange 2007, lacked any Exchange, or OS, multi-site, storage redundancy, data centers with very stringent availability SLAs were forced to install and utilize SANs spread over multiple physical sites. Such SANs have exactly the cost profile to which Alan refers.
With the advent of Exchange 2007, and now Exchange 2010, the Exchange disk I/O has been considerably reduced — by 70% in 2007 and by another 70% in 2010. This has two two knock on impacts:
1. Exchange can now make use much less expensive, though slower and less reliable, IDE (SATA II) disk storage.
2. Exchange Journaling volume is now low enough to be piped to remote Exchange servers.
From an administrative standpoint, Exchange 2010 has made it trivial to create and sync. storage to other servers. In fact, Microsoft is strongly recommending maintaining two or more storage replicas as an alternative to employing local RAID 1, 10, or 5 storage. I would strongly concur with this recommendation. The time taken to rebuild multi-terabyte RAID arrays (4-8 days) is just too long, and deleterious of performance.
So, though he needs to multiply his numbers by a factor of 2 or 3 to cater for remote server-based redundancy, David is also fundamentally right.
So net/net if you have already sunk all the costs of a SAN infrastructure and there is no alternative demand for it, stick with it when considering a move to Exchnage 2010.
If organizations are looking to invest in additional disk infrastructure for Exchange 2010, or there are other demands for existing SAN infrastructure, then consider making use of Exchange 2010 locally attached IDE disks with Exchange 2010 remote storage redundancy.
More feedback suggesting that the cost of storage is substantially more than I figured:
“Approximate cost of NetApp RAW Fiber Channel is $18,000/TB. Most customers run Exchange 2010 in RAID 10 which means two copies so that makes it $36,000/TB. If you assume a replicated Exchange environment, that’s $72,000/TB. Microsoft recommends against using RAID and replicating, but most clients will be reluctant to do that.”
With many thanks to LiveOffice’s Dean Nicolls.
Alan,
Many thanks for the response indicating I’m substantially understating the cost of common storage. I fear you are right and that I’ve got egg on my face. Hopefully we’ll get more responses on this and if necessary we will publish a correction. Thanks again for this very helpful input–David
Enterprise storage systems are complex networks comprised of redundant infrastructure, switching gear and highly paid engineers to make it all work. The going rate for a 1TB of RAW Fibre Channel storage is ~ $5,000-10,000/TB, a figure that must be multiplied by 5-10X to account for storage controllers, data snapshots, disaster recovery sites, data center costs, network capacity and FTE load. At a loaded cost of $25,000/TB a 30GB mailbox really costs ~ $750/user. iSCI might reduce this number by 50-60%, but still a major investment and a performance trade-off.
A quick call to your local HP, EMC, NetApp or IBM partner will confirm that a fully redundant/high Performance SAN solution is a major investment and the reason why most Enterprise CIO’s are not wiling to fund 30GB at this time.
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