Mailinglist Archive: opensuse (2348 mails)

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Re: [opensuse] Software IDE RAID versus hardware IDE RAID
  • From: Sam Clemens <clemens.sam1@xxxxxxxxx>
  • Date: Wed, 02 Apr 2008 17:26:49 -0400
  • Message-id: <47F3FA19.6090208@xxxxxxxxx>
John Bown 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?

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)
2) Enable Encrypted File System (EFS)

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.

Get some modern SATA disks.
They're doing I/O at 300 Gbyte/s now.
While they don't have out-of-order queueing like SCSI
and SAS, they do offer high burst speeds for I/O (Serial
Attached SCSI...same cables but use SAS cards -- which
conveniently can ALSO control SATA disks, too. Each port
individually determines if that cable is attached to a
SATA or an SAS disk.



Since the machine has two 2.4GHz Xeon processors in it, couldn't I
designate one to do nothing but RAID and encryption,

That would be the master/slave CPU model of running a *nix
kernel. While it was cutting edge in 1982, it was obsolete
by 1985.

> 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?

Considering that your 2.4 GHz processor runs several orders
of magnitude faster than your disk drives can send or
recieve data, AND that most controllers have bus-master
capability, there's really no point in this. Disk I/O
has very little impact on modern CPUs, unless you're
running Serial Attached SCSI, and say, doing several
hundred thousand database transactions/second on a
database which is spread across a few thousand disk
drives. And even then, the overwhelming majority of
the disk I/O load will be on the bus-master controller
cards, not the CPU cores.


Thank you for your collective time.

We're her to help.
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