New Webserver with multiple drives
support at drasticproductions.com
Mon Jul 28 08:36:32 PDT 2003
That explains it perfectly! However, let me throw this on the pile and let me have your opinion on it:
1) Hardware load balancing is an option (or so I found out from the people that built the server) .. Using ATA133 RAID. Being this is an option, should I hardware LB or software LB?
2) Personally, I like the idea of having 400gbs available. This server is a web / database / email / dns server. However, I'm desperately trying to see this in a more advanced light than "WOW, 400 gigs! WOOHOO!" :) That being said, is Raid 1 the best way to go? If it slows down writes, will it be noticeable? The one thing I DON'T want is noticeable speed lost. Is the Raid becoming corrupt in Raid 0 a common thing? I generally don't add to servers, I buy new ones.. So when I outgrow this production machine, it will get demoted to something else and I'll buy a bigger better production server. (meaning the chances of me adding additional harddisks is unlikely)
3) Does it matter that I'm planning an offsite location? Essentially, I'll backup all the web / email / db stuff to a server offsite. Although my backup server isn't as big as my production server (right now), I don't have 400 gigs of crap. I figure when I've outgrown my backup server, I can simply replace it.
Many thanks for all your help.. It's greatly appreciated!
Duane A. Stark
Drastic Productions, LLC
duane at thinkdp.com
> ------------Original Message-------------
> From: Matthew Seaman <m.seaman at infracaninophile.co.uk>
> To: Duane Stark <duane at drasticproductions.com>
> Cc: freebsd-questions at freebsd.org
> Date: Mon, Jul-28-2003 3:22 AM
> Subject: Re: New Webserver with multiple drives
> On Sun, Jul 27, 2003 at 06:20:27PM -0500, Duane Stark wrote:
> > To preface this, I'm not OS retarded - just BSD retarded ;) I haven't had to mess with my current BSD server since I bought it, and now I have purchased a new p4 3.0(something), 2 gig ram, 2 IDE 200gig HD's to replace it..
> > Here is my question:
> > How do I setup these multiple drives? What does the "industry" recommend when it comes to setting them up? Should I set BSD up to think its one datasource (so 400gig) and then run from that? Or do I setup 1 drive to hold my web/mail/mysql, and the other to do something elsE?
> > I'm totally lost, so any help would be greatly appericated.. PLEASE don't assume I know what your talking about, because it's a given that I dont! heh :)
> The only possible answer is "it depends". With disks there are 3
> characteristics that you can modify the balance between depending on
> your needs. Those are resilience, available space and access speed.
> There's also a fourth consideration, which may affect your choice but
> that has little effect during the day-to-day operation of the system,
> which is the amount of time and effort you're prepared to put into
> doing sys-adminly things.
> Now, you've only got two disks, so that immediately rules out any
> choices involving RAID5. You make no mention of any sort of hardware
> raid controller, so I'll assume that isn't a possibility either.
> That leaves essentially 3 choices:
> i) No RAID at all. This scores highly on the ease of admin, as
> it's the default way things are set up by sysinstall. Just
> partition the disks, put filesystems on them and set up
> /etc/fstab so the partitions get mounted in appropriate
> locations. I'll take this as the baseline to compare the other
> setups to.
> ii) RAID 0 or disk striping. This creates one synthetic 400Gb
> partition from your two actual drives, by writing alternate
> blocks of data to each drive. The block size is configurable:
> at one extreme you could make the block size the same as the raw
> disk size, in which case you'ld end up appending one disk to the
> end of the other. However, the greatest advantage occurs when
> the block size is round about the same size as the system can
> read from the drive in one gulp. This spreads the load of any
> IO evenly of the two drives and should maximize performance.
> The bad news is that if either of the disks becomes faulty, then
> all of the disk space on your system will be unavailable. As
> you add disks to the stripe, this problem becomes more and more
> acute, so this setup is generally not used very much unless in
> combination with RAID 5 or RAID 1 to give higher resilience.
> iii) RAID 1 or mirroring. Each drive contains a complete copy of all
> of the data, maintained in parallel. The advantages are
> improved resilience -- the system should just keep chugging
> along merrily even if one of the drives self destructs -- and
> improved IO performance on reads -- writes have to go to both
> drives, which takes only slightly longer than writing to a
> single drive, but reads can go to either drive which gives you
> much better performance. (The biggest factor is the
> milliseconds it takes to position the head and wait for the
> drive to turn round until the correct block is under the head.
> Talking between the CPU, RAM and the disk electronics takes of
> the order of microseconds.)
> The bad news is that you've got to sacrifice half of your
> potentially available disk capacity. However, assuming that the
> resulting space is adequate for your needs, a mirrored root disk
> setup is pretty standard for server machines.
> Either of ii) and iii) will probably entail your learning about
> vinum(8) as the best available mechanism for doing software RAID on
> FreeBSD. The alternatives are not that hot: ccd(4) is pretty ancient
> and doesn't offer any means of recovering a mirrored partition than
> backup and re-install should one drive fail. I've heard that NetBSD's
> raidframe stuff is being ported to FreeBSD, but I don't think it's
> ready for primetime use yet.
> for a thorough introduction to vinum bootstrapping,
> http://www.vinumvm.org/ for general information and
> http://org.netbase.org/vinum-mirrored.html for a quick HOWTO set up a
> bootable vinum root drive.
> Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
> Savill Way
> PGP: http://www.infracaninophile.co.uk/pgpkey Marlow
> Tel: +44 1628 476614 Bucks., SL7 1TH UK
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