Mailinglist Archive: opensuse (2348 mails)

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Re: [opensuse] Software IDE RAID versus hardware IDE RAID
  • From: "Greg Freemyer" <greg.freemyer@xxxxxxxxx>
  • Date: Tue, 1 Apr 2008 11:09:01 -0400
  • Message-id: <87f94c370804010809x5ad13e1pb7926fb32a376917@xxxxxxxxxxxxxx>
On Tue, Apr 1, 2008 at 10:40 AM, John Bown <john.bown@xxxxxxxxxxx> wrote:
Hello everyone. I have an old server with an IDE RAID card in it on
which I'd like to install openSUSE 10.3. The problem is, support for
said RAID card (a Dell CERC ATA/100) has been discontinued for some time
now. With that I ask, how feasible and/or advisable would it be to
attempt the following?

Linux typically does not drop support for a very long time.
Effectively if there is even just a couple users they tend to keep the
source in the kernel. I would not be one bit surprised to find there
is a module that supports your hardware raid.

But, at least on new hardware linux raid is very efficient, and you
are just doing raid-1 which takes very few resources anyway.

1) Install openSUSE and configure it to use software RAID (two mirrored
IDE drives (master/slave) for system, two stripped IDE drives
(master/slave) for data)

I guess you just have 2 IDE channels? If so, you want to keep your
pairs together a little differently I suggest.

I would go with system (master / master), data (slave / slave). That
way when you are doing writes to only the data drive you get to use
both channels simultaneously. If you have both on the same channel,
you have to perform writes sequentially. (ie. half the speed).

2) Enable Encrypted File System (EFS)

That is you performance killer I suspect.

Basically, I'm worried that an IDE based machine will be painfully slow
due to the high disk activity. Ideally I would use the machine's
existing SCSI U320 interface, but the required hard drives are just too
expensive.

If you stick to one drive per channel, IDE is not so horrible. The
next step up is SATA. If you stick to software raid, you should be
able to get a PCI sata controller at a reasonable cost.

Since the machine has two 2.4GHz Xeon processors in it, couldn't I
designate one to do nothing but RAID and encryption, thereby leaving the
other processor free to do everything else, such as running virtual
machines? If so, can anyone point me in the direction of a good online
how-to?

I suspect that will just happen. If the encryption you are using is
kernel based I'm afraid I don't know how to pin it to one cpu only.
If your using a userspace encryption (like the fuser based encryption
encfs) then you should have no problem pinning it to one cpu.

Greg
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