What is a good choice of sata-ii raid controller for freebsd?
clay at milos.co.za
Fri Feb 9 15:49:32 UTC 2007
----- Original Message -----
From: "Artem Kuchin" <matrix at itlegion.ru>
To: <freebsd-stable at freebsd.org>
Sent: Friday, February 09, 2007 5:15 PM
Subject: Re: What is a good choice of sata-ii raid controller for freebsd?
> Alexander Sabourenkov wrote:
>> Artem Kuchin wrote:
>>> I am the original poster of this thread. I have read many interesting
>>> reply during these two days. However, as i said in the original
>>> message due to certification issues i am pretty limited to INTEL
>>> controllers and i have not seen a single relevant reply about them.
>>> This is interesting. Nobody uses Intel controllers on FreeBSD or
>>> they just suck that much?
>> If you have enough SATA ports and no need for fancy RAID levels,
>> then my advice is to use gmirror.
>> Hardware RAID1 buys you nothing in perfomance and reliability
>> for a prolonged headache with drivers, bios insanity and
>> monitoring+control tools.
> Hm... two points here. I, somehow, do not really believe that
> software raid (gmirror for example) is as reliable as hardware.
> I, deeply inside, believe that i might screw things very badly under some
> heavy load and bad timing conditions. Can't explain it. it is religious i
> but i can be very wrong about this.
> However, two perfomance point:
> Under gmirror OS must issue two commands to write to disks and some
> commands to check/set mark that mirrored data is intact.
> Under hardware RAID OS issue sonly one command to write and no
> checking command, since raid controller handles this async.
> So, software OS raid must be slower than controller based raid anyway.
> Am i right here? Any benchmark data on this?
> As for reliability of gmirror. I just need to know how it works to see
> for myself that if power turned off in some racing condition gmirror will
> know that
> disk are out of sync. If it is done than gmirror must check sync of disks
> every read, and
> that mean two command for reading too, which must slow down things.
> Is it true?
I set up 3 RedHat Enterprise servers in a cluster for a customer 2-3 years
ago. Dual P4-XEON 3.4GHz with 16G of ram each.
Really lovely servers. Intel server motherboards with 2 x15k RPM SCSI drives
as a mirror for the OS and fibrechannel external storage for Oracle 10i.
The SCSI RAID on the motherboard was horrifically slow. I'm talking around
5MB/s hardware raid for 15k RPM SCSI drives. Turns out it was a known bug on
the Intel motherboards with no workaround or fix so I set the boxes up with
Linux software raid. The performance was excellent and they are still
running perfectly today. I think the SCSI controller was Symbios or
something like that.
Ever since then I have not trusted Intel and RAID in the same sentence. I
was really upset that they were not interested in fixing the issue. I even
emailed Intel to ask them about it and they said there was not much
likelihood of a fix.
Call me biased but that's just what my experience has taught me.
Btw the Areca cards have Intel RISC CPU's on them and they are lightning
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