Subject: Re: software RAID vs hardware RAID
From: Damien Hull (dhull@digitaloverload.net)
Date: Fri Mar 14 2003 - 12:22:23 AKST
Looks like I'm going with software RAID.
As for /root needing to be on the array, yes. It needs to be on the
array because you need to be able to boot off of it.
If /root or /boot, depending on how you set it up, isn't on the array
and one drive fails then you loose your kernel. No kernel means no more
system.
On Fri, 2003-03-14 at 12:17, Joshua J.Kugler wrote:
> On Friday 14 March 2003 11:42, Damien Hull wrote:
> > 1. It seems more difficult to repair or fix a bad drive
>
> It shouldn't be, as the software drivers should detect the new drive and take
> appropriate action. There might be a rebuild command that has to be issued
> from the command line.
>
> > 2. Including /root in the RAID array requires a work around
>
> True, but if *I* did a setup like this, I would probably have a system drive
> for /, applications, etc, and then put data (mail, database, etc) on the RAID
> partition (even if I used symlinks).
>
> > 3. Performance will be better with hardware RAID
>
> Yes and no. With mirroring and striping, you are simply writing (or reading)
> data to/from two drives. There is no real overhead involved. With RAID 5,
> you are computing checksum bits, so writing will be slower with software
> RAID, but reading should be just as fast.
>
> YOU SHOULD ALSO KEEP IN MIND: IDE raid cards from Promise. Adaptec, and
> HighPoint are not true hardware RAID! They use system drivers to do the RAID
> 1/0/1+0 operations. In fact, I've heard that there has been admission (by
> said companies) that the Linux software drivers are actually better than
> their proprietary drivers. I believe the only true hardware IDE RAID card
> out there is from 3Ware.
>
> > The RAID array must be able to keep the system running even if one of
> > the drives fails. This means I need to have /root mounted on the array.
>
> Umm...I don't think that's correct. Are you sure?
>
> > Also, I'm using Debian so any info on getting software RAID working
> > under Debian would be a big help.
>
> There is a RAID utilities package, that should make things easier.
>
> > So far I like the money saving aspect of software RAID but it looks like
> > I might save my self a lot of time and a headache or two using a
> > hardware solution.
>
> Maybe...reading the man pages for the RAID utilities should tell you all you
> need to know. I'm sure there is a RAID HOW-TO. Also, the RAID drivers for
> Promise, Adaptec, etc, do funny things to the drive, and write housekeeping
> data in funny places. You might just be better off with Linux RAID if you
> are just doing mirroring.
>
> Hope that helps.
>
> j----- k-----
>
> --
> Joshua Kugler, Information Services Director
> Associated Students of the University of Alaska Fairbanks
> isd@asuaf.org, 907-474-7601
>
-- Damien Hull Network Administrator www.digitaloverload.net--------- To unsubscribe, send email to <aklug-request@aklug.org> with 'unsubscribe' in the message body.
This archive was generated by hypermail 2a23 : Fri Mar 14 2003 - 12:22:45 AKST