Recently I’ve been looking at CleverSafe’s Storage Cloud product and as part of the research I noticed that a small scale DSNet provides more than enough IOPs for small scale mailbox installations.

I took a selection of decommissioned mid-range [Pentium Dual Core / SATA I Disks etc] Workstations to which I installed CentOS 5.0 and the CleverSafe software. 4 IDE SliceStores and an Accesser provides enough IOP throughput for around 50 mailboxes. Ramping this up to 6 SATA SliceStores and there is enough IOP throughput for 70 mailboxes.

We’re obviously not talking about large scale Enterprise / Data Centre solutions here but for a small scale Exchange install [I'm thinking Test Lab setups maybe at a push a SOHO install] that needs reliable disk storage this seems to work quite well especially if used as the target storage for LCR [Consider that powering up a couple of old workstations is probably cheaper than the purchase of a decent SATA II hardware RAID card and extra disks.]

Utilising a 1Gb/s Network would improve the throughput considerably but for this test I was only utilising 100Mb/s between the Accesser and the Exchange server with a latency of around 40m/s so a constant Read Throughput of 2.8Mb/s will have to do.
 
 
DSNet offers access to the Storage ‘Vault’ via an iSCSI interface so there isn’t any extra work involved in preparing the Vault for use with Exchange 2007. Since this isn’t a normal SCSI device you have to disable “Synchronous Transfer” and “Tagged Queuing”. Their purposes are detailed here. Since these are enhancements to the operation of SCSI it shouldn’t adversely affect the operation of Exchange.

With the disks mounted and formatted it was a simple matter of changing the Queue and DB locations with PowerShell:
Move-StorageGroupPath -Identity "Second Storage Group" -LogFolderPath:"D:\Mailbox\Second Storage Group" -SystemFolderPath:"D:\Mailbox\Second Storage Group"

Running the Exchange server for a couple of days shows no degradation in usability even when a DSNet storage Vault was used for the Mailbox stores as well as the LCR.

Looking at other DSNets that are out there and looking at the potential for improvements in this DSNet then it may be possible to scale a DSNet out to production grade usability, if I have enough time and can get hold of some newer SATA II disks, better machines and a gigabit LAN infrastructure I’ll do a proper experiment and see what can be acheived.