Date: Mon, 27 May 2002 09:36:20 +0200 From: Holger Kipp <holger.kipp@alogis.com> To: Phil Rosenthal <winter@villaweb.net> Cc: "Kenneth D. Merry" <ken@kdm.org>, freebsd-stable@FreeBSD.ORG Subject: Re: Hardware RAID vs vinum Message-ID: <3CF1E1F4.9D9C8C1D@alogis.com> References: <004701c20530$68e98a20$0700a8c0@zoom> <20020526230050.A8026@panzer.kdm.org>
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"Kenneth D. Merry" wrote:
>
> On Sun, May 26, 2002 at 23:41:39 -0400, Phil Rosenthal wrote:
> > I've been using vinum for about a year now, and have been using it on some
> > pretty large, heavily accessed RAID5 file system (500GB & 70MBits/sec
> > constantly ).
> > Is there any reason why a hardware raid would be better, am I missing out on
> > anything?
>
> As someone else mentioned, CPU utilization, and possibly features,
> depending on the RAID card.
Nowadays, the CPU utilization might not be an argument for file servers, as they
usually have no CPU utilization. For larger Database-applications I'd always
recommend hardware raid, though, especially if using RAID 5 (don't use cheap
cards without hardware RAID 5), to avoid cache poisoning.
RAID solutions that only use RAID 0 and 1 don't require hardware raid IMHO,
but for production use, hot spare support, rebuilding of array in background, etc.
might be an issue. Use RAID 0+1 (10) for maximum performance ;-)
With hardware raid, you're bound to one controller, though. With software raid,
you can mirror across controllers etc.
> > What hardware RAID cards are best under FreeBSD 4.6?
IMHO the supported ones are a good choice ;-)
> I would recommend an Adaptec 5400S. It has a hardware parity engine to
> accelerate RAID-5 parity calculations, so writes will be faster than on a
> RAID card without a parity engine.
We use
- 3ware Escalade 7850
If you need RAID 5, but want to use cheaper IDE hard disks. Otherwise,
7810 might do (no hardware raid 5 support).
- AMI MegaRAID (Dell PERC 3)
If you use a DELL server ;-)
- Mylex AcceleRAID 352
No problems so far - but then, each is for different requirements, you better
have a look at
http://www.freebsd.org/releases/4.5R/hardware-i386.html
and choose the one best suited for your requirements ;-)
Regards,
Holger
--
Holger Kipp, Dipl.-Math., Systemadministrator | alogis AG
Fon: +49 (0)30 / 43 65 8 - 114 | Berliner Strasse 26
Fax: +49 (0)30 / 43 65 8 - 214 | D-13507 Berlin Tegel
email: holger.kipp@alogis.com | http://www.alogis.com
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