How to make things fast …

September 28, 2011

I recently returned from one of my overseas jaunts (country will remain unnamed to protect the innocent) … where I found a general attitude towards making things go fast.

That was … use 15K SAS drives.

Simple as that. Don’t worry about which RAID card you use, or which RAID type you use for your different data sets, just use SAS drives for everything and that’s how you make the fastest server you can make.

While in principle I agree that for fileservers you should use SAS drives – they are fast, reliable and getting larger by the day, but to use these drives for every server type is missing the point when it comes to building a server to suit your needs.

10K and 15K SAS drives have a great advantage over SATA drives when it comes to seek time – so general file serving and database work will benefit greatly from these drives – but for video work I don’t personally see the need to use these drives. SATA drives (enterprise of course) are not far behind SAS drives in sequential throughput, and a dramatically cheaper and larger – meaning you can use more spindles in a SATA environment than you can afford to use in a SAS environment – and that’s what will really give you the speed in a streaming environment – spindles.

(While re-reading this article before posting, I actually find I’m disagreeing with myself on this point (slightly). 7200rpm SAS drives (commonly called “nearline”) seem to be the best go for this sort of work. The SAS interface gives these drives a slight performance improvement over their SATA counterparts and therefore are my favoured drives for many types of storage.)

Add to that the fact that certain RAID types are suited to different data environments and you can make a big difference to the speed of the system by using the correct RAID level for your data (eg don’t use RAID5 with database).

When I showed some of my customers results from a couple of my crazy Australian customers doing unbelievable speeds on video with nearline SAS drives – people were stunned. They had been told, and firmly believed, that to make something fast you needed 15K SAS drives.

Not so (not all the time at least).

Therefore, think about the drive types you are using, and about building a server to suit your data – not just filling the box up with expensive fast drives and hoping that will do the job.



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