Thanks for that information, that sounds like a good idea. The only thing that concerns me is that in googling for LVM, I'm worried that it's an extra layer of complication that may not be that stable as yet since it needs devfs .. or am I talking out of my a$$ and have seen too many scare stories? I like your idea of splitting the swap and root partitions out to separate RAID1s.. I guess I could do something similar even without LVM. Thanks :) Derek /paranoid he's gonna choose the wrong thing and hose himself 6months down the line. On Wed, 12 Jan 2005 00:26:33 +0000, Robin Bowes <robin-lists@xxxxxxxxxxxxxx> wrote: > Derek Piper wrote: > > Hi, > > > > I revised my idea and thought about RAID 1+0 for some partitions, > > since there are 4 drives. This outline below might clarify what I was > > trying to mention earlier. Is this a feasible set-up that would be > > bootable (kernel compiled-in md, I'm no stranger to compiling > > kernels)? I'm interested to hear comments/opinions since I've never > > done this before. Like I said, it'll be running on a Dual-pentium pro > > 200 (W6-LI) machine, I have no idea if machines of that vintage have > > the 'cojones' for software raid or not. > > > > My ideas of RAID1+0 / RAID5 disk system partitions > > MB > > /dev/hde 60GB 57241 (from controller) > > /dev/hdf 60GB 57241 (from controller) > > /dev/hdg 60GB 57241 (from controller) > > /dev/hdh 80GB 78125 (unconfirmed) > > > > /dev/hd* = applies to all drives considered here > > > > Device MB Type GB Mountpoint MD device RAIDed size (MB) GB > > /dev/hd*1 20 RAID1 + 0 0.02 /boot /dev/md1 40 0.04 > > /dev/hd*2 192 RAID1 + 0 0.19 Swap /dev/md2 384 0.38 > > /dev/hd*5 2048 RAID1 + 0 2 / /dev/md5 4096 4 > > /dev/hd*6 2048 RAID5 2 /home /dev/md6 6144 6 > > /dev/hd*7 52933 RAID5 51.69 /data /dev/md7 158799 155.08 > > > > Does swap being raided make sense? I hear that sometimes it's a good > > idea since a disk failure won't make you crash and then I heard > > elsewhere that it doesn't matter and the kernel automatically raids > > swap partitions anyway. I prepared the above in a spreadsheet btw so I > > could work out partition sizes. > > > > Thanks in advance again for any comments. > > > > Derek > > > > On Tue, 11 Jan 2005 13:47:20 -0500, Derek Piper <derek.piper@xxxxxxxxx> wrote: > > > >>Hi, > >> > >>I am new to RAID / md devices, although I've used Linux for a number > >>of years. I decided it was high-time I had a RAID at home for > >>important things (email, web-sites, son's baby pics, mp3s etc.). I > >>happen to have a 3 Seagate 60GB hds and 1 80GB Seagate hd that I am > >>considering using for a RAID. > >> > >>My question is this, is it possible (and even a good idea) to use all > >>4 hard drives as members of a 4 x 60GB RAID5 array by leaving 20GB of > >>the 80GB drive as a non-raided partition? I'll be using a Promise > >>Ultra TX2/100 controller. > >> > >>i.e. > >> > >>hde -> 60 > >>hdf -> 60 > >>hdg -> 60 > >>hdh -> 60/20 > >> > >>I heard about RAID6 too, though I'm assuming that will use up another > >>disk's worth of disk space too. > >> > >>i.e. RAID5 = 180GB usable size,wherease RAID6 = 120GB .. am I correct > >>in my thinking? > >> > >>I know many of you use far larger hard drives, I'm just trying to use > >>the components I already had spare from a number of machines and > >>reorganize to a RAID-backed fileserver. > >> > >>The machine is a dual pentium-pro 200 (320MB RAM) .. would that be a > >>dumb idea to use RAID5 on it because of the parity calculations > >>needed? > >> > >>Further to that, would it be a smarter idea to use RAID1 on all 4 of > >>some small partition(s) at the start of the disks to house > >>boot/root/usr partitions, and only RAID5 on a larger 'data' area of > >>the drive that is more likely to be read than written to? > > Derek, > > I have a machine with 6 x 250GB SATA disks, but the configuration I use > would work just as well for you. Here's what I'd do: > > Partition all your drives the same. > Create one small partition of 1GB, plus one large partition using up the > rest of the disk (i.e. around 59GB), *except* the 80GB drive. On this, > create a 1GB partition, a 59GB partition, plus a third partition using > up the rest of the disk (i.e. around 20GB) > > Assuming these drives are /dev/hd[efgh], configure them as follows: > > /dev/hd[ef]1 /dev/md0 / > /dev/hd[gh]1 /dev/md1 swap > /dev/hd[efgh]2 /dev/md2 lvm volume group > /dev/hdh3 - use for whatever you want! > > Now, use lvm to create logical volumes in your large volume group. I > have created /var, /use, and use the rest for /home. > > These are my arrays: > > [root@dude slimserver]# mdadm --detail --scan > ARRAY /dev/md1 level=raid1 num-devices=2 > UUID=be8ad31a:f13b6f4b:c39732fc:c84f32a8 > devices=/dev/sdb1,/dev/sde1 > ARRAY /dev/md2 level=raid1 num-devices=2 > UUID=826170e2:cdd598d4:d212c9b1:6602deef > devices=/dev/sdc1,/dev/sdf1 > ARRAY /dev/md5 level=raid5 num-devices=5 spares=1 > UUID=a4bbcd09:5e178c5b:3bf8bd45:8c31d2a1 > devices=/dev/sda2,/dev/sdb2,/dev/sdc2,/dev/sdd2,/dev/sde2,/dev/sdf2 > ARRAY /dev/md0 level=raid1 num-devices=2 > UUID=4b28338c:bf08d0bc:bb2899fc:e7f35eae > devices=/dev/sda1,/dev/sdd1 > > These are the lvm logical volumes: > > [root@dude slimserver]# lvdisplay > --- Logical volume --- > LV Name /dev/audio_vg/usr_lv > VG Name audio_vg > LV UUID qseH0A-wKgo-xhB5-2tJ4-Qnxx-VOML-0eb43m > LV Write Access read/write > LV Status available > # open 1 > LV Size 10.00 GB > Current LE 160 > Segments 1 > Allocation inherit > Read ahead sectors 0 > Block device 253:0 > > --- Logical volume --- > LV Name /dev/audio_vg/var_lv > VG Name audio_vg > LV UUID nzH8uf-LhyU-o5My-tK48-ckaw-xzfL-esbfj4 > LV Write Access read/write > LV Status available > # open 1 > LV Size 5.00 GB > Current LE 80 > Segments 1 > Allocation inherit > Read ahead sectors 0 > Block device 253:1 > > --- Logical volume --- > LV Name /dev/audio_vg/home_lv > VG Name audio_vg > LV UUID zbixtc-S6mb-MTVR-WXGw-dkjG-EU9q-WeZItv > LV Write Access read/write > LV Status available > # open 1 > LV Size 914.38 GB > Current LE 14630 > Segments 1 > Allocation inherit > Read ahead sectors 0 > Block device 253:2 > > This is what my filesystems look like: > > [root@dude slimserver]# df -h > Filesystem Size Used Avail Use% Mounted on > /dev/md0 1.4G 357M 985M 27% / > /dev/mapper/audio_vg-var_lv > 5.0G 1.4G 3.3G 30% /var > /dev/mapper/audio_vg-usr_lv > 9.9G 2.4G 7.0G 26% /usr > /dev/mapper/audio_vg-home_lv > 915G 142G 764G 16% /home > > And finally swap: > > [root@dude slimserver]# swapon -s > Filename Type Size Used > Priority > /dev/md1 partition 1469816 224 -1 > > R. > -- > http://robinbowes.com > > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Derek Piper - derek.piper@xxxxxxxxx http://doofer.org/ - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
