Re: SCSI vs SATA

For random IO, the 3ware cards are better than PERC

 > Question: will 8*15k 73GB SCSI drives outperform 24*7K 320GB SATA II drives?

Nope.  Not even if the 15K 73GB HDs were the brand new Savvio 15K screamers.

Example assuming 3.5" HDs and RAID 10 => 4 15K 73GB vs 12 7.2K 320GB
The 15K's are 2x faster rpm, but they are only ~23% the density =>
advantage per HD to SATAs.
Then there's the fact that there are 1.5x as many 7.2K spindles as
15K spindles...

Unless your transactions are very small and unbuffered / unscheduled
(in which case you are in a =lot= of trouble), The SATA set-up rates
to be ~2x - ~3x faster ITRW than the SCSI set-up.

Cheers,
Ron Peacetree


At 06:13 PM 4/3/2007, jason@ohloh.net wrote:
>We need to upgrade a postgres server. I'm not tied to these specific
>alternatives, but I'm curious to get feedback on their general
>qualities.
>
>SCSI
>   dual xeon 5120, 8GB ECC
>   8*73GB SCSI 15k drives (PERC 5/i)
>   (dell poweredge 2900)
>
>SATA
>   dual opteron 275, 8GB ECC
>   24*320GB SATA II 7.2k drives (2*12way 3ware cards)
>   (generic vendor)
>
>Both boxes are about $8k running ubuntu. We're planning to setup with
>raid10. Our main requirement is highest TPS (focused on a lot of
>INSERTS).
>
>Question: will 8*15k SCSI drives outperform 24*7K SATA II drives?
>
>-jay
>
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