Booting order / SATA onboard / IDE card

[Lennart Sorensen]

On Fri, May 14, 2010 at 12:29:46PM -0400, D. Hugh Redelmeier wrote:
> | From: Alex Beamish <talexb-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org>
> 
> |  The original NFS server is
> | running openSolaris and the drives are using ZFS, in case anyone's
> | curious.
> 
> I'm not really plugged into the OpenSolaris world, but I wonder how
> much longer it will be supported.  The few things I've heard from
> Oracle don't make me optimistic.
> 
> If you are building a new box, perhaps FreeBSD would be a better
> platform.  It supports ZFS.  I have no idea if it understands raw
> OpenSolaris disks.
> 
> | The intended replacement is a P4 3GHz Dell machine which has a single
> | 80G SATA drive. I was planning on buying two 500G or 1T SATA drives as
> | the data disks (RAID 1, mirrored), and installing an IDE card for a
> | small, inexpensive system disk. However, now I'm wondering whether the
> | BIOS on this new machine will be flexible enough to be able to boot
> | off the IDE disk; I'm new to SATA drive machines. Anyway, that's plan
> | A, and my preferred solution.
> 
> Dell boxes can sometimes surprise you with things that they are
> missing.  Check if there are places to mount all the drives you want.
> Check if there are enough SATA ports (probably).  Check if there is
> already a PATA port (sometimes they exist for optical drives).  Think
> about cooling.  See what booting options your BIOS provides.
> 
> If you plan on running the server 24/7, you might think about power
> consumption and heat too.  The fewer spinning disks, the better.  The
> fewer P4 processors, the better (0 is optimal).
> 
> The incremental cost of a larger SATA disk may be similar to than the
> cost of an IDE (parallel ATA) card.  Getting larger disks rather than
> an IDE card might reduce the bother and you should end up with a
> bigger NFS partition because the OS would only take a tiny fraction of
> the additional space.
> 
> (Or you could use the same size disk and forgo a few gigs of NFS space
> to allow for the OS installation.  But I'm greedy: you can never have
> too much disk space (until it comes time to back it up or fsck it).)
> 
> Consider getting two 1.5T drives, using the first (modest) partition
> on each for the OS, unmirrored, and using the rest of each drive in
> RAID1.  Note: I've not tried this; I'm just assuming that it can work.
> 
> Why two OS partitions?
> 
> 1. symmetry -- the drives will have identical partitioning.
> 
> 2. I always have at least two OS partitions so I can install a new OS
>    without blowing away the old one.  Real disk space is so cheap that
>    it isn't much of a waste (10G/$, so an OS partition costs a
>    dollar or two).
> 
> It is true that there might be contention between OS partition
> accesses and the RAID partition accesses.  If the thing is only an NFS
> server, I'd expect most OS partition accesses to be satisfied from the
> filesystem cache so contention ought to be minimal.

Why would anyone not raid everything?  Do you like wasting half a day
reinstalling the OS when the drive fails?  Sure you didn't loose your
data because it was on raid, but you lost access to your data, which is
almost as bad.

People who think swap and the OS don't need to be on raid when the data
is are just amazingly stupid.  If the machine crashses in the middle of
an access, it doesn't matter that your data is on raid, you can still
screw it up.

You put it all on raid or you don't bother.

-- 
Len Sorensen
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