[LAU] Hard drive for "/" should be also 7200 rpm?

[Hakan Koseoglu]

On 19 February 2012 21:25, Michelle Konzack
<linux4michelle at tamay-dogan.net> wrote:
> IF you are professional, go  ahead  and  buy  a  4  channel  Raid-0  SAS
> controller with 3-4 REAL SAS 10.000 RPM drives.
I'd love to see a FAKE SAS drive.

> Note:  REAL SAS drives have MORE physical heads and a seek time of <2ms.
>       Remember, that SAS/SCSI drives have special size like 36, 72, 74,
>       146, 147 and since some time 300 and 600 GByte.   All  other  are
>       SATA drives with ONLY an SAS interface which will not help you.

Only 4 years ago, 4TB SAS
http://www.theregister.co.uk/2008/04/08/seagate_1tb_sas_drives/

2 years ago, 2TB SAS:
http://www.seagate.com/ww/v/index.jsp?locale=en-US&name=constellation-es-seagate-ships-first-2tb-pr&vgnextoid=8e9d5669418e6210VgnVCM1000001a48090aRCRD

A year and a bit ago, 3TB SAS:
http://www.storagenewsletter.com/news/disk/hitachi-gst-3tb-ultrastar-7k3000

Also the physical properties of the disks don't matter much apart from
the RPM hence the seek time and a bit with the number of the platters
(not as much as the RPM). The rest are identical between SAS and SATA
apart from the interface. The enterprise-level disks also tend to come
from better-end of the quality testing, that makes a difference to the
failure rate thus they also cost more.

If you want real performance, go for 15k SAS drives but they will do
damage to your bank account but will have very short seek times but
the performance increase is usually not that significant. Here's an
ancient but a good read:
http://www.tomshardware.com/reviews/sas-hard-drives,1702.html

On the other hand, the idea of just having SAS having a higher
performance is a fiction. SAS-3 gives you 6Gbit/s bandwidth. SATA-3
gives you 6Gbit/s bandwidth. SAS has better error protection etc. and
just because it's more enterprise, better quality of disks but it
doesn't mean it is just faster. Thanks to SAS disks supporting SCSI
protocol, you can have multipathing etc. but those don't apply to
desktops, mainly server-side business.You used to get additional
performance on SCSI ends (serial or parallel) by having queueing
implemented but new SATA drives have similar technologies too.

Compare the details for yourself:
http://en.wikipedia.org/wiki/Serial_attached_SCSI
http://en.wikipedia.org/wiki/Serial_ATA

All said, having SAS drives & cards is not a bad idea. You will be
using better tested hardware and will have lower failure rates. If
this is important, paying for the extra amount is worth it. Also using
good SAS interface with loads of memory and on-board battery will make
sure that at a failure your data will be written to the disk. On the
other hand you will not get a lot of these on consumer-grade hardware,
you will need a noisy server but almost all servers
(HP/Dell/IBM/Fujitsu etc.) will supply you with a somewhat decent SAS
interface and, if you have serious data requirements, external
enclosure with no performance penalties. Just keep the server away
from your recording studio!