Hardware RAID support? Which controller best to use?

Roger Marquis marquis at roble.com
Sun Nov 20 04:17:34 GMT 2005

Olaf Greve wrote:
>>   I've had far better luck using SATA over SCSI in the recent couple of years.
>> We have several machines setup using FreeBSD and 3Ware RAID 0+1 that routinely
>> run with no problems and uptimes of 200 to 300 days at a time.
> Very interesting to know. At present, I myself have a 754 socket AMD
> Athlon 64 3.2 GHz (IIRC), running FreeBSD 5.4 release AMD-64, with an
> Adaptec 2200S U320 SCSI RAID controller with 4 Maxtor Atlas 10KIV 36GB
> drives attached to it in RAID-10 mode. So far it works a charm (though I
> too had to effectively downgrade it to U160 due to the lack of 64-bits
> PCI slots, grrr).

For most applications the MTBF of SATA equals that of SCSI and has
for several months now.  You can run into maintenance problems by
not being able to map-out bad blocks under SATA but then drives with
those should be swapped out anyhow.

Sadly, the fast LSI SCSI RAID drivers either don't exist for FreeBSD
or are not mature.  Adaptec SCSI RAID is also not as well supported
as some of the SATA RAID cards.

The critical difference between SATA and SCSI RAID, aside from
price, is performance under load.  In this department SCSI still
outperforms SATA by a substantial margin.  Add 15K drives and FCAL
and you're talking night and day.  Then again, most servers that
need this kind of IO run Solaris and also benefit from all the
software (Veritas, Legato, ...) built for it.  Most FreeBSD servers,
OTOH, will do nicely with SATA.

ray at redshift.com wrote:
>Basically, you just install the card, boot into the RAID bios
>using Alt+3 and then you follow a simple menu to build whatever
>type of raid you want.

Jeez I wish they wouldn't do that, require ctl or alt keys that is.
Alt key menus are worthless through a serial console.

Roger Marquis
Roble Systems Consulting

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