Hot Swap hardware on FreeBSD?

[Jesse Guardiani]

Stephen P. Cravey wrote:

> I'm trying to locate a good resource for creating hot swap capable servers
> with FreeBSD and Vinum.
>
> Specifically, I'm trying to find out several things:
> 
> Are there resources somewhere that document this type of thing? Please?
> 
> Do I need controllers for SATA/SCSI that will handle the
> plugging/unplugging of drives, or do I just need to do a bus rescan (or
> the like) after the change and notify vinum?

I'm not sure that you can do hot-swapping with vinum. Please let me know
if you get it to work.

Typically you'll need one of the following:

1.) Firewire external drives
2.) SCA SCSI drives.

If you go with #2, you'll probably be getting a hardware RAID card with the
deal and IT will manage your volume if a drive goes bad. In that case you
shouldn't have to do anything under FreeBSD (assuming you're actually running
one of the redundant RAID levels, and not just striping).

I'm also not sure that you can use SATA for hot swapping. If you CAN, then
you'd either need a hardware RAID card as with SCSI above, or you'd need to
unmount the drive and issue an `atacontrol detach` command before removing
the drive.

> i.e. do i need something like
> an adaptec 2200S or will a 39320 work?
> 
> Is there anything in particular I should look for when buying hot swap
> chassis? Other than SCA for SCSI?

SCA works well on my machines at work. Other than that, you can find multi-
drive firewire cases online.

[...]

> Where can I find (recent) performance numbers for raid 0,1,5 comparisons?

That's a very broad question. How fast are your drives? What's your interface
(i.e. Firewire? SCSI-160? SCSI-320? ATA?) Will you be using vinum or a
hardware RAID controller? Which hardware RAID controller (they're DEFINATELY
not all created equal!)?

In general, you'll probably get optimum speed with vinum. However, it'll chew
up your CPU and it might not be as reliable as a hardware solution.

-- 
Jesse Guardiani, Systems Administrator
WingNET Internet Services,
P.O. Box 2605 // Cleveland, TN 37320-2605
423-559-LINK (v)  423-559-5145 (f)
http://www.wingnet.net



>From aaa at aaa Mon Jan 01 00:00:00 1997