This came in this morning’s email from a reader I’ll call Perplexed. How would you advise Perplexed?

I’m looking at a new iSCSI storage system for two sites with ~ 20 servers each – 10TB each should do it. Picture two fairly usual manufacturing/mining sites, 200-500 users, email, file/Print, finance and production database services, MS Domain etc.

Looking at IOPS – we would be serviced by 24 x 2.5″ SAS 10K disks in a RAID6 array.So – the thought occurs – that SSD would easily match that performance with far less devices.

Say 15 VM’s and 5 Servers per location. Requirement for about 5TB of data with limited growth – lets say 10TB storage and under 1000 IOPS.

Throughput is not an issue except for backup and DR. If we can saturate 2 or 3 Gigabit Ethernet links that is adequate.

This would be served comfortably by 24 x 10K 2.5″ RAID6 arrays at each location. Two of them for redundancy.

But – a single Intel 710 SSD could meet that IOPS rate and probably throughput as well. One SSD disk replacing an entire 24 disk array!

I would then ask, why have RAID at all? RAID is based on spindles being the smallest block for failure. With SSD, that block could be much smaller. The controller is already doing some ECC for wear management with overprovisioning.

Is there a new paradigm the granularity is no longer a “spindle”? Should we simply over-provision by 50%? SSD generally comes with provisioned spare capacity – starting to sound like redundancy and error correction is built into the controllers to some degree already.

What would be ideal is a 1RU box full of 10TB solid state storage with 10G iSCSI – no separate disks.

Has SSD let us start to move beyond RAID? With the death of spindles and the huge IOPS available, is the entire R1, R5, R6, R10 debate finished? Does RAID have it’s place in a box full of chips, and if yes, does it look the same as what we know?

Has the world started to change in storage, or is SSD still just non-moving spindles?

10TB, 1000IOPS, 10G iSCSI – how would you buy it?

Readers, what say you?
What suggestions do you have for Perplexed? The IOPS are low and he doesn’t suggest heavy bandwidth requirements either. But he does seem very interested in reliability.

Update: Vendors are welcome to comment. I only ask that you identify yourself as such. End update.

The StorageMojo take
Aside from cost – I’d expect a minimum of $4-$5 per gigabyte or ≈$100k+ for the storage – the low IOPS requirement means SSD could be overkill. Perhaps a hybrid SSD/disk solution? SSDs can and do fail, so relying on a single SSD is as dangerous as relying on a single HDD.

A number of companies might be appropriate, including Nexsan, Nimble, TwinStrata, Nexenta, Nutanix, Tintri, Violin, Pure, Nimbus, Tegile and Avere among others. Some have features, such as WAN replication or cloud backup, that might prove useful. Others have VM support, but not with iSCSI.

Performance isn’t likely to be an issue with any of these vendors, so I’d focus on availability, management, support and then look at cost.

Courteous comments welcome, of course. I’ve done work for some of the companies mentioned.