[Repost - for some reason my reply from earlier this morning did not go through] Thanks everyone for all your suggestions/comments. >Ask yourself this question: Does the company loose money when the build system >is down for restore? How much? How long does a restore take? No, no money lost. If I keep a spare drive, it should take less than an hour to restore the system. > Mirroring disks is not a replacement for backup. It is a way to improve > availability of a system (no downtime when a disc dies), so it might even be > interesting when there is no important data on the machine. If this is > important for you use RAID-1 for the entire discs. I would waste the most disk space, but this is certainly a possibility. > If decreased availability is not a problem for you (you can easily afford a > day of downtime when a disc dies) use RAID-0 for the entire discs. It will > give you a nice performance boost. Especially on a build host people will > love the extra performance of the disc array. But if either disk dies, the whole system is unusable. I don't think I will use this option. > A combination of RAID-0 and RAID-1 may also be an option: Make a small RAID-1 > partition for the operating system (say 20GB) and a big RAID-0 partition for > the data. This way you will get maximum performance on the data partition, > but when a disc dies you do not need to reinstall the operating system. Just > put in a new disc, let the RAID-1 rebuild itself in the background and > restore your data. This can reduce the downtime (and the amount of work for > you) when a disc dies considerably. Hmm, this sounds like a possibility. I have to figure out how to do this (I haven't used HW RAID before). > HW vs SW RAID: Kind of a religious question. HW has some advantages when using > RAID-5 or RAID-6 (less CPU load). When using RAID-0 or RAID-1 there should > not be any difference performance wise. HW RAID gives you some advantages in > terms of handling, i.e. hotplugging of discs, nice administration console, > RAID-10 during install ;-), etc. It's up to you to decide whether it is worth > the money. Plus you need to find a controller that is well supported in > Linux. Does anyone know if the RAID controller that comes in an IBM x3550 is supported on CentOS 4 & 5? I assume that it is. > P.s. Putting lots of RAM into the machine (for the buffer cache) has more > impact than RAID-0 in my experience. Of course that depends on your > filesystem usage pattern. The system has 4GB. > P.p.s. Creating one swap partition on each disc is correct, because swapping > to RAID-0 is useless. Only if you decide to use RAID-1 for the whole disc you > should also swap to RAID-1. Will do. > Three raid1 sets: > > raid1 #1 = / > raid1 #2 = swap > raid1 #3 = rest of disk on /home > > for the simple fact that a dead disk won't bring down your system and halt your > > builds until your rebuild the machine. Yes, I like that. > But if you really only care about max speed and are not worried about crashes & > > their consequences, then replace the raid1 with raid0. I like the earlier suggestions on combining RAID0 and RAID1. > I have no reason for using LVM on boot/OS/system partitions. If I have something > > that fills the disk that much, I move it to an other storage device. In your case, > striped LVM could be used instead of raid0. That's why I can't decide what the best approach is. So many different ways to skin this cat. Thanks, Alfred