On Thu, April 15, 2004 9:15, Gordon Henderson said: > On Thu, 15 Apr 2004 robin-lists@robinbowes.com wrote: > >> Does this look feasible? Can you see any major gotchas? Any better >> suggestions? > > Personally I'd keep life simple at the expense of a little disk space - my > layouts are also based on wanting to split partitions to, so I'd never put > /, /usr and /var on the same partition - historical reasons, including > fsck time and maybe a distrust of very old PDP11 Unix systems... (Yes, > I'm a boring old fart) Anyway what I do with my own machines (and those I > build for others) is as follows: I do the same thing. I thought that I could create separate partions on top of the RAID-5 array, like I would with hardware RAID (I have some experience with a Compaq SMART-2P and external storage rack). If that's not the case then I shall re-think accordingly. > Partition each disk identically. That way, if you need to swap out a > drive, you already have a copy of what it's partition table ought to look > like by simply looking at the other drives - sort of self documenting if > you like. Makes sense to me. > So for a single disk system it might look like: > > sda1 256MB / > sda2 1GB swap > sda3 2GB /usr > sda4 Rest of disk /var > > Actually, /usr might be less and swap would be double memory, but you get > the jist - use the 4 primary partitions and usually no more. In olden days > consideration would be made to where the disk head spends most of its time > - here, oscillating between the /usr (programs) and /var (data) might be > optimal, but I don't think anyone cares about this these days. > (historically, /usr was where users home directories lived too, then the > head would be between /usr and swap and /bin with special programs having > the 'sticky bit' set to make them reside in memory or swap to make them > quicker to load) > > Partition the drives similar to this in a RAID system too. Then combine > them as follows: > > sda1 and sdc1: RAID 1 / > sda2,b2,c2,d2: RAID 5 swap > sda3,b3,c3,d3: RAID 5 /usr > sda4,b4,c4,d4: RAID 5 /var > > You "lose" 2 partitions: sdb1 and sdd1. You can combine these in another > RAID1 if you like, but it's not much use for anything. OK, I get the picture. > Putting swap on RAID5 probably isn't optimal, but if your machine is > swapping heavily, buy more memory. If you are really tight on disk space > and know you have plenty of RAM no swap is probably better than too little > swap. I'll probably put the swap on a mirror, i.e. RAID-1. > You might need to adjust the sizes of the swap and /usr partitions - I > usually aim for 2GB under /usr (that would be 4 x 768MB partitions under > RAID5) - I've found that to be enough for Debian and X and space for other > stuff, but YMMV. Remember with a 4-disk RAID 5 system you get 3 times the > capacity. > > Debian also puts /home under /, so I always remove it before creating any > users and create a /var/home and symlink /home to /var/home. > > If it's just a home server and you don't anticipate the log files growing, > you may want to consider not having a separate /var partition and mounting > that as /home instead... I usually create several partitions and put as much as possible on separate file systems, e.g. /var, /home, /usr, /opt, /tmp, /var/qmail/queue. I might reconsider that if I have to do the same on every disk! I may even look into using EVMS so I can configure all of this with a common interface. > You need to make sure you can actually boot off sdc1 should you ever lose > sda. This is vitally important! Most SCSI controllers allow you to change > the boot drive, so it shouldn't be a problem, but it might mean manual > intervention should you need to reboot it in a degraded mode. I'll do some tests to make sure I can do this. > > I've not used a /boot partition for about 8 years now. As far as I'm aware > it was just a "hack" when BIOSes couldn't boot from cylinders > 1024, and > putting / on the very first partition sorts this anyway. /boot on my > servers is just a directory under / on all my machines. Yeah, probably. I just do it as a matter of habit now. It doesn't cost anything, other than an additional partition. > Knowing that you are only using 4.3GB drives, I might be tempted to merge > the /usr and /var partitions. How do you mean? Thanks, R. -- http://robinbowes.com - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
