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nofam
16-02-2009, 08:52 AM
I'm in the process of spec'ing a new server for our in-house POS system, which is a large multi-table, multi-user database, running on Redhat Linux. Traditionally we've always used IBM pSeries gear, running AIX, but Redhat Enterprise is now the preferred option.

The spec that's been suggested has SATA drives, which concerns me for a 24/7 server. I'd like some advice on:

1. The reliability of SATA vs SCSI, not so much in terms of MTTF, but more which is more susceptible to bad sectors etc.

2. The performance of SATA vs SCSI in terms of command queuing on a busy database with heavy I/O

TIA!! :thumbs:

pctek
16-02-2009, 09:03 AM
Here:

http://www.umich.edu/~umce/linux/mail-archive/msg00492.html

robsonde
16-02-2009, 11:02 AM
1. The reliability of SATA vs SCSI, not so much in terms of MTTF, but more which is more susceptible to bad sectors etc.

2. The performance of SATA vs SCSI in terms of command queuing on a busy database with heavy I/O

TIA!! :thumbs:

1. the internals of the drive are almost the same, so MTTF will be much the same, on SCSI disks you they have been "run in" a bit more. as for bad sectors and such you will find it all to be much the same.

2. there are many kinds of SCSI, so the answer is maybe....
cache, spin speed, command queing and all such come in to the mix


if it was my box I would use mirrored SATA2 drives with big cache.

dont get too large a disk if you want good MTTF, the bigest disk on the market are always the ifrst to fail, they push the tech as far as they can.

in out server enviroment we never use more than 250GB in a single disk.

johnd
16-02-2009, 09:29 PM
As stated above the physical parts of the drive may be exactly the same.

As I understand it all PATA and SATA drive speeds are quoted in burst mode - not sustainable transfer rates. SCSI is sustainable. There is no doubt in my mind that a modern SCSI system is faster than SATA ... but is the speed and cost needed?

SolMiester
17-02-2009, 05:58 PM
SATA drives wont have the bandwidth of the SCSI disks, especially if you are talking heavy use DB I/O...In fact now SAS (Serial SCSI) are the preferred disks.