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The last time I worked with a 3Ware RAID controller it was 2004, and it was a 9000 series SATA. It lived up to its marketing hype - I personally benchmarked it exceeding 100MB/sec on RAID5 writes - an impressive result for the time. The largest controller available was a 12-port job, so the largest array you could build was an 11 disk RAID5 - if you wanted a hot spare. Still, the combined seek performance of 11 drives was significant.

3Ware have built on this performance. Their 9500 series card claimed approximately 500MB/sec RAID5 writes, and a 16 port model. Now, with their 9650SE series, 3Ware are claiming 600MB/sec RAID6 writes (800MB/sec reads) and 24 disks in an array.

What does this mean?

3Ware 24 Disk 600MB/sec RAID6: An affordable mini-SAN?

Let me put it into perspective. Today, the fastest widely available disk storage for businesses comes from 4Gigbit Fibre Channel connections to a large Storage Area Network. This means using optic fibre to send and receive data from a large number of disks (small SANs may only have perhaps 8 or 12 disks, but they range up to hundreds or even thousands) at a little bit over 400Megabytes per second.

Now, if the fastest throughput available from top-end Big Business storage systems is 400MB/sec, and a RAID controller that costs a couple of grand can write at 600MB/sec and read even faster, something is wrong.

(above: Chenbro case capable of taking the 3Ware 3650 series card with a full rack of 24 SATA drives)

Of course, throughput is only a fraction of the story. The most important aspect of enterprise storage performance comes down to a basic limitation of the hard drive: it’s a spinning disk. When you want a particular chunk of data, you move the heads into the right position, and wait for the data you want to rotate under them.

With a 15,000rpm enterprise hard drive, the total time taken averages about 3 milliseconds, meaning that one hard drive can generally perform roughly 333 operations per second. The fastest SATA drive today is a 10,000rpm ‘Raptor’ from Western Digital, which can manage around 222 operations per second. So a ‘Mini SAN’ made up of 24 of the fastest available SATA drives will only be about as quick in terms of operations per second, as 16-drive array of 15,000rpm fibre-channel drives.

Still, that puts a fully-fitted 3Ware/Western digital array ahead of IBM’s entire range of ‘Entry Level’ SANs - which run up to 12 disks - in every performance category. Oops.

You need to go to the middle of IBM’s ‘mid-range’ to get 16 15,000rpm disks working together, and currently IBM’s website tells me that a DS4700 express with 16 tiny 36GB 15k RPM disks will set me back just over $39,000 Australian (about $36k US).

Meanwhile, the 3Ware controller comes in under $3k, 24x 36GB 10,000rpm Enterprise grade WD Raptors will set you back about $4k, and on a bad day a rackmount case with 24 hot-swap SATA bays like the one from Chenbro pictured above will be a little over $2k. Of course, you need a server motherboard/cpu/ram to throw in the case, so let’s splurge and add $5k for that. 14 grand all told, for the same or better performance than an IBM SAN costing closer to 40 grand.

Naturally, the IBM SAN comes with dual redundant controllers, and you can purchase the fabled IBM support with it. But hey, for 14 grand, buy two of your 3Ware solution - put one offsite and solve your disaster recovery problems at the same time.

Where I work, we have a 28x 15,000rpm disk array just for a single database - so we wont be investing in 3Ware in the near future. We also benefit from IBM support, and having IBM on our tender applications. On the other hand, for most small or medium businesses, the capital outlay of buying all that equipment is far more important - and so the better value 3Ware option really shines.

Of course, I haven’t talked about networking that storage - that’s a topic for a future article

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Posted in Storage, Technology Choice |