Marc Bevand <[EMAIL PROTECTED]> wrote:
> > Be very careful about that. 73GB SAS drives aren't that expensive, so
> > you can get 6 x 73GB 15k SAS drives for the same amount as 11 x 250GB
> > SATA drives (per Sun list pricing for J4200 drives). SATA doesn't
> > always win the IOPS/$. Remember, a SAS drive can provide more than 2x
> > the number of IOPs a SATA drive can.
>
> Well let's look at a concrete example:
> - cheapest 15k SAS drive (73GB): $180 [1]
> - cheapest 7.2k SATA drive (160GB): $40 [2] (not counting a 80GB at $37)
> The SAS drive most likely offers 2x-3x the IOPS/$. Certainly not 180/40=4.5x
I am not going to accept blanket numbers... If you claim that a 15k drive
offers more than 2x the IOPS/s of a 7.2k drive you would need to show your
computation. SAS and SATA use the same cable and in case you buy server grade
SATA disks, you also get tagged command queuing.
Let's use a concrete example:
For 10 TB you need ~ 12 1TB SATA drives (server grade) -> 2160 Euro
96 Watt stand by
~ 1 GByte/s sustained
read
Max IOPS -> 1200
For 10 TB you need ~ 165 73 GB SAS drives -> ~ 22000 Euro
2475 Watt stand by
~ 4 GBytes/s sustained
read if you are lucky
and have a good
controller
Max IOPS -> 34000 (not realistic)
More important in this case: the MTFB os the SATA based system is much bigger
than the MTBF of the SAS based system.
In theory, you really get 2x-3x the IOPS/$, but do you like to pay as many $
and do you like to like to pay for the space and the energy?
Jörg
--
EMail:[EMAIL PROTECTED] (home) Jörg Schilling D-13353 Berlin
[EMAIL PROTECTED] (uni)
[EMAIL PROTECTED] (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/private/ ftp://ftp.berlios.de/pub/schily
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
