Joe Tseng wrote, On 03/26/2008 10:37 AM:
I saw a few people respond with saying how hardware RAID is overkill for
home use. I had the system drive in my RH9 RAID1 file server at home
die on me last year; although I got a new drive and FC6 recognised the
RAID immediately I'm not sure whether my recovery was due to software
resilency or dumb luck. I'm currently working on gathering parts for a
RAID5 file server as a replacement.
1) If a RAIDed drive dies in a soft RAID setup can I assume I can't do a
hotswap?
based on my limited information, I would say soft RAID only has a _chance_ of
doing hotswap if the hardware connected to it can do hotswap. however I don't
know if md supports "hotswap" or even being told "stop using the drive
temporarily so I can turn it off in hardware and swap it".
2) If my system drive dies again would a new system recognize my RAID5
array?
That is the beauty of soft raid under Linux, as long as the RAID5 routines
remain the same the new kernel can use them.
3) Does soft RAID5 compare favorably against hware RAID5?
Remember, at it's heart all RAID 5 is software.
in general:
hardware raid = controller card/box with a built in CPU doing all the RAID
calculations and spreading the data across buses and drives.
software raid = main CPU of the system doing all the RAID calculations and
spreading the data across buses and drives.
Difference = your main CPU can be used for other things if you have hardware
to offload the job to.
however seeing as most "hardware RAID" uses a very small/slow CPU, your main
CPU may not notice the extra load of software RAID. :)
And some true hardware raid solutions still have problems, see my pain:
http://lists.freebsd.org/pipermail/aic7xxx/2005-October/004274.html
http://lists.freebsd.org/pipermail/aic7xxx/2005-August/004259.html
http://lists.freebsd.org/pipermail/aic7xxx/2004-July/004160.html
- Joe
----- Original Message ----- From: "Albert Graham" <agraham@xxxxxxx>
To: "For users of Fedora" <fedora-list@xxxxxxxxxx>
Sent: Tuesday, March 25, 2008 1:18 PM
Subject: Re: Raid Card controller for FC System
Most modern motherboards will all you to have 4 or 6 SATA drives
connected, so the cheap solution is to use Linux software raid, that's
the best bang for your buck you're gonna get :)
--
Todd Denniston
Crane Division, Naval Surface Warfare Center (NSWC Crane)
Harnessing the Power of Technology for the Warfighter
