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Re: RAID Suggestion for webserver

> On Mon, 11 Feb 2002 06:34, Jason Lim wrote:
> > Okay... for those of you following the previous RAID discussion... I
> > bought the 3ware cards.
> >
> > Each server has 4 40G hard disks (identical). What RAID level/config
> > you suggest?
> > Main usage is web/database/mail server (the usual hosting setup). Disk
> > performance isn't THAT important, but reliability is.
> Why not go the whole hog and put all the drives in a RAID-1 and have 4
> of all your data?

Err.. that would reduce usable space all the way down to 40Gs, and provide
the worst write performance in history, wouldn't it? Okay I know
performance isn't the primary concern, but that does sound like a massive
waste to have 4 copies of the same data. I doubt 3 drives would die
simultaneously... or at least, the odds are very much in my favour of that
not happening ;-)

> For a mail server, database server, or other machine where you can only
> one copy of the data you want to be really paranoid about the drives.

Like in most hosting environments, each server is "self contained". That
is, each account's services (www,ftp,mail,etc.) are on the same server as
the account. While it would be ideal to separate them all out onto
specialized servers, it isn't too practical (and we don't load the servers
that high...  50 small-mid sized accounts per server).

> For a web server I suggest having two servers.  Use RAID-1 for simple
> mirroring of the data (if only to save yourself the effort of
reinstalling a
> server after a minor hard drive error).  For anything serious have load
> balancing at the switch or have a manual take-over proceedure to make
> other machine get both IP addresses.  Having a redundant server saves
> from memory errors, CPU over-heating, and other hardware problems (which
> probably more likely than having two hard drives die at the same time).

I actually thought about that. Since each server will have 4 disks. We
could operate 2 RAID 1 arrays 2 + 2. If an error occured on the server
(eg. CPU burnout), we could pull out 2 of the HDs (one from each array)
and slot them into a backup server... that would get the backup server up
very quickly, while the CPU can be slowly replaced (or whatever was wrong
with the server).

However, something is telling me the above will not work, unless we get
ANOTHER 3ware card for the backup server. I am not sure i 3ware's RAID 1
writes any proprietary information to the disks, making them unusable
without the 3ware boards.

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