Jim Baxter <[EMAIL PROTECTED]> wrote:
>I have been told that very few people if any use software raid.
>Do any of you use it?
I use it, but only for filesystems like /home and /var as RAID-1
filesystems. I don't (and wouldn't) use it for any filesystem required at
boot time. I use rsync and a simple bash script scheduled via cron to
periodically synchronize a "cold" copy of the boot disk. In the event my
primary boot disk failed, I can swap the disks and be on my way. I do have
to keep lilo updated on both disks or boot from floppy if I need to spare
disk, but you might have to do that anyway with a software root-RAID1
system, depending on which disk failed.
I have my doubts about whether a software root-RAID1 setup would survive a
disk failure or if it would need to be rebooted. My *theory* is it would
depend on if the server was SCSI or E/IDE and which disk in the mirror
crashed. If the primary disk failed, would the secondary be bootable
without moving it and so on...that's why I've been using rsync and a "cold"
copy of the boot disk. If I needed a server that *absolutely* had to
survive a disk failure without needing a reboot, I'd go with hardware
RAID. Costs more, yes, but disk failures are generally detected/handles by
the BIOS and unless there's some sort of monitoring daemon running, the OS
*might* not even know a disk had failed.
That said, there's also the much-improved reliability of modern disk
drives. The reasons we use RAID today are not the same reasons we used it
a few years ago - disk drives have gotten much bigger (no need for RAID0)
and much more reliable, especially "brand-name" SCSI drives.
>What is your opinion of it?
Obviously not as good or bullet-proof as hardware-RAID, but not as
expensive and for the filesystems I use it for, it suits my needs just
fine. If push comes to shove, I can always restore the OS and
configuration files from my backup tapes, so I primarily use RAID1 for data
that changes frequently - /home and /var.
>Does it support 0/1?
If you mean RAID levels 0 & 1, then yes. It also supports 5 and possibly 2
- 4, but I'm not sure about those.
>Do you have a feel for any performance degradation that might be caused by
>it?
Not really. The servers I run it on are all SCSI and *somewhat*
over-engineered. ;-) I also haven't been running it all that long so it's
a bit hard to tell yet.
-Eric
Eric Sisler
Library Computer Technician
Westminster Public Library
Westminster, CO, USA
[EMAIL PROTECTED]
Linux - don't fear the Penguin.
Want to know what we use Linux for?
Visit http://gromit.westminster.lib.co.us/linux
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