[AusNOG] Server/HD Question

[jason andrade]

On Thu, 14 Feb 2013, Chris Ricks wrote:

> 1. I think we all mean 7.2K drives - 7.5K drives are quite hard to get,
> as they don't exist. :-)

And there's no overclocking capability..  ;-)

> 2. There are 2 types of 7.2K drives - nearline SAS and SATA. There's
> very little to split these in terms of performance, but depending on the
> server they're being shoved into, a nearline SAS device may have better
> connectivity to the backplane (and shouldn't require a pesky interposer).

A nearline sas drive has two main points to consider:

o It uses SAS electronics/protocols rather than SATA (NCQ rather than TCQ is one example)
    and generally will connect at 6G speeds to the storage backplane rather than 3G for SATA.

o It is still using the same SATA physical drive mechanism and as such you can
   assume bit error rates of 10e14 - i.e think about it as being a sata drive.  An
   enterprise SAS drive will have a bit error rate of 10e15.  You care about this
   when designing raid arrays and so on.

In short, nearline is the middle ground between the expensive but generally faster
(10k/15k rpm) but smaller capacity enterprise drives and the cheaper, slower 
desktop/consumer aimed drives.

Frankly for a few small VMs, just put in a couple of SSDs and forget all about mechanical hard drives.

It's still a bit strange seeing this discussion in amongst the v4, bgp, dsl, internet
filtering discussions on ausnog.. oh well, i guess the network is not in fact the
computer..

regards,

-jason