Date: Tue, 27 Mar 2001 14:48:59 -0600 From: "Jeffrey J. Mountin" <jeff-ml@mountin.net> To: <scanner@jurai.net>, Ed Henderson <Ed.Henderson@Certainty.net> Cc: isp@FreeBSD.ORG Subject: RE: Good server motherboard? Message-ID: <4.3.2.20010327142640.02e18100@207.227.119.2> In-Reply-To: <Pine.BSF.4.21.0103271239230.75629-100000@sasami.jurai.net> References: <002f01c0b6dd$8538e560$0464a8c0@pnt004>
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At 12:42 PM 3/27/01 -0500, scanner@jurai.net wrote:
>On Tue, 27 Mar 2001, Ed Henderson wrote:
>
> > You mention that I should consider software RAID if I only need level
> 1. How much processing overhead is there? My system will be running
> with a single 1.2GHz Athlon CPU.
>
> Software RAID like Vinum has proven to be faster then HW
>RAID. Mainly because of HW Raid card's using poorly sized stripes. There
>is a benchmark test of Vinum vs some DPT Cards that brad knowles put on
>the web. If you want the URL I would be happy to dig it up for you. Vinum
>is FAST++, and you can enable softupdates on Vinum as well. So you get
>speed and reliability. And I use this combo on alot of Postfix mail
>servers for the mail queue. I couldn't be happier. Vinum is
>incredible. Now I just have to keep working on some decent doc's for it
>:-)
Processing overhead is negligible, even when rebuilding objects.
The comparison with DPT doesn't apply to the newer cards, but in general
Vinum and hardware raid are comparable in terms of performance.
True, you cannot boot off a Vinum volume (yet), but there are several ways
to allow for minimal downtime.
Only problem that Vinum has is with RAID5, which bites various users from
time to time. In most cases it is better to go with a 0+1 setup for better
write performance than level 5.
Another advantage is no special controller is needed. However, it would be
advisable to have plexes ("mirrors") on different controllers to allow for
hardware failure. Otherwise it should fit you low budget needs more than
sufficiently.
If the lack of boot support in Vinum is an issue that could be solved with
a 2 port 3Ware card and a couple IDE drives. There are boards with onboard
RAID support, but it is considered crude at this time and not a good
solution for production servers. Check the -stable archives for more info
on the Promise and HighPoint controllers.
IMO, recovery is easier with Vinum than with hardware RAID and with a hot
swap enclosure no downtime is needed. Some HW RAID controllers require
booting a DOS disk or the FBSD drivers are not as yet full-featured. Of
course with Vinum you need to write some kind of script to monitor things,
but that goes with the territory.
Jeff Mountin - jeff@mountin.net
Systems/Network Administrator
FreeBSD - the power to serve
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