[CentOS] Serial ATA hardware raid.

Sun Apr 17 04:06:58 UTC 2005
Bryan J. Smith <b.j.smith@ieee.org> <thebs413 at earthlink.net>

From: Les Mikesell <lesmikesell at gmail.com>
> Note that software mirroring has some advantages too and is not
> a big performance hit as long as the underlying hardware uses
> DMA and works independently (i.e. don't do it with drives
> on the same IDE controller cable).

Actually, I wouldn't do it on the same PCI bus.
With drives able to burst at 50MBps, the amount of traffic on your interconnect can actually be high.

> I consider it a big plus to be able to take a drive from a mirrored pair, plug
> it into just about any computer without worrying about having
> exactly the same brand of controller, and recover the data - or
> take over the service the broken computer was providing.

Then you'll like 3Ware.
For RAID-1, it doesn't change the organization.

But even if you use RAID-0, 0+1 and RAID-5, the great thing about 3Ware is you _can_ safely move the drives to _any_ model card, as long as the firmware is at least the same or newer.
I have done this with volumes from 5000 to 6000 or 7000, 6000 to 7000.

> And by the way, there's nothing wrong with running a DNS server
> and mail server on the same machine - but you should have a 2nd
> dns server which can also provide other services. 

A secondary mail server is always a good idea too.
Ideally, you should consider a chroot environment or even an UML instance for each.

> You might need a bit more RAM but DNS typically is not a big cpu load.

But you are correct from a load standpoint, neither will hit you too much.

Bryan J. Smith   mailto:b.j.smith at ieee.org