Kevin Myer <[EMAIL PROTECTED]> writes:
> To improve redudancy and speed, I would think I want to split up the
> drives across the different controllers, i.e put one 4.5 Gb drive on
> backplane 1 and 1 4.5 Gb drive on backplane 2 and split the 9Gb drives
> across the backplanes as well. The controllers are embedded Symbios
> 53c875's. I assume moving the drives will reorder the SCSI devices, so
> that what was one sdb may now be sdf for example. Is that a correct
> assumption and is my logic regarding redundancy and speed correct?
Yes.
You don't need to worry about the device name reordering, though,
because the persistent superblocks that allow the RAID subsystem to
autoconfigure itself contain the necessary information about the RAID
device each drive/partition belongs to. So, as long as you have all
the RAID partitions set to partition type 0xfd and they autostart
correctly, you can freely move the disks around (with the exception of
the first disk, since that's where the BIOS needs to load the kernel
image from).
However, if you have a system mirror disk on the second controller,
the BIOS will probably be unable to use that disk to boot the system
in case the first disk crashes. Keep an up-to-date boot floppy with
the correct kernel image around. Once the kernel has been loaded, the
problem is bypassed.
The RAID-5 will crash anyway if either of your controllers fails,
because it can only handle one disk failure.
> Secondly, I will be using the arrays for file serving to SMB and
> Appletalk/Appleshare IP clients. What chunk size would one recommend for
> such a setup? Files will range in size from 1k to roughly 50-100Mb.
> Also, some clients can only accurately see 2Gb partitions. Will I take a
> big performance hit if I partition what would originally be one big RAID 5
> composed of 9Gb drives into smaller chunks composed of partitions of the
> 9Gb drives?
I'm using chunk-size of 32, it's a bit on the low side but I didn't
bother doing much analysis into an optimal size. However, at least if
you're using Samba 2.0 and Netatalk 1.4b2-asun, you don't have to do
anything about the 2G issue. Yes, clients think the volume only has 2G
available, but that's because the server is lying to them to keep them
happy. It'll work just fine.
--
Osma Ahvenlampi
