Re: The last of the questions, hopefully.

On Fri, May 31, 2002 at 12:49:53AM -0500, Vitaly McLain wrote:
> 1. If I have that "Embedded Adaptec AIC-7899 dual channel Ultra3
> (Ultra160)/LVD SCSI" controller, in order to hook up two SCSI drives to it,

Well, the 'D' in 'LVD' stands for differential, which as you'll recall from
that nice summary someone posted is the two-goat version...

> I just need to make a SCSI chain or whatnot, right...? (Can you tell I am a

Leaving aside the goats, a SCSI chain is one bus (type of cabling required
varies with the type of SCSI) with appropriate termination (type of
terminator varies ditto) at each end and two or more devices connected (type
of connector...) at appropriate points (yeah, there are rules about minimum
distance between connection points as well as maximum overall bus length,
but I can't recall if the minimums vary with the type of SCSI; the maximums
certainly do).

That's all.  :-)

> 2. If we have two drives in a RAID 1 configuration, and one fails, what
> would the effect be? From my readings, it seems as if 3 drives in RAID 5
> would handle this just fine, but RAID 1 would not handle this well. If

I think you've got RAID 1 confused with striping, which is by bad tradition
sometimes referred to as "RAID 0".  There's a certain literal charm to that,
since striping is indeed no RAID at all, but it's confusing.  Anyway, RAID 1
is mirroring, so if one drive fails the mirror runs on as a non-redundant
disk, with all the data intact.  It's the *second* failure that causes great
pain.  :-(

> 3. If a RAID 1 drive fails, and a new one is put in as a replacement, what
> would need to be done to get it up to speed, as far as getting it in sync as
> a mirror? How about if a drive fails in RAID 5?

Depends on the system.  Anything from "just wait", if the RAID system allows
hot plugging and automatically begins reconstruction to... well, maybe you
have to shutdown to safely replace the drive, and reconstruction may even
need to be manually started.  Might even need to complete before you can
bring the array back online, though probably not for any modern
implementation.  (I've seen that with Linux's software RAID 1 - imagine fsck
running while the mirror is rebuilding itself.  Be sure to use a good UPS
with a power fail monitor to do a clean shutdown to avoid having to see this
needlessly!)

> 4. Would a server running a P3 1.13Ghz with 256Mb PC133 ECC SDRAM be able to
> handle software RAID (Windows 2000 Server...ugh)? Would making it 512Mb RAM
> help?

Don't tempt me.  Just don't.

-- 
And in the end, reality always tends to hit theory hard
in the face when you least expect it.  - Linus