On Sun, Sep 02, 2007 at 08:44:21AM +1000, Alex Samad wrote: > On Sat, Sep 01, 2007 at 09:48:38AM -0400, Douglas A. Tutty wrote: > > On Sat, Sep 01, 2007 at 12:16:00PM +1000, Alex Samad wrote: > > > raid 1 / raid 1 /boot raid 5 - pv > > > > > > I have been looking at why not to raid 5 and I would go to raid 10 > > > but I can only put 3 drives in my machine. > > > > > > Currently have 3x250G and am looking at getting 3x500G, if I go to > > > mdadm raid1, then I have 500G safe 500G unsafe which is not really > > > what I want. > > > 1 big vgroup and lots of lv's some with mirrors and some without ? > > > > I don't see a mirror option in Etch's LV create. > > Okay I have lenny but I thought mirroring had been in for a while, > from my man lvcreate > > -m, --mirrors Mirrors > > I haven't looked at this previously so I might be wrong.
Before Etch came out, when I knew that its installer would be doing LVM, I decided that when I moved from Sarge that I'd go with LVM. On Sarge's lvcreate, there was a -m --mirrors option. When Etch came out it wasn't there. I haven't looked into why not but its not there. To me, its the one big thing missing from LMV. I suppose though that if we all start mirroring in LVM instead of setting up md, then we'll need an LV version of mdadm to email us when a mirror degrades from a failing drive. > > > > > Here's how I would do it: > > > > Partition 1: 3-way raid1 64 MB for /boot > > I usually go for 500M, leaves me lots of room to leave stuff not sure > why 3 way though, the spare space on the 3rd drive if i go 2 way i use > for tmp or swap or ... > If you don't have swap protected, then a failed drive could crash the system. Put the swap on LVM. You could also put / on LVM but I didn't suggest that since you seemed to want to keep it to a non-LV. I have two drives, 70 GB each. 3 partitions: md0 for /boot, md1 raid1 for LVM VG-mirror for the system stuff and then the two third partitions for VG-cat for non-mirror protected stuff. /home is on a regular LV, /var/tmp is on a striped LV. /tmp is on tmpfs. I'm running amd64 and have a 300 M LV for / with ext3 gives 291 MB total and I have 170 MB used with 107 free with two kernels and their modules installed. I suggested that you go with 3-way raid1 since you have three huge drives anyway, you wouldn't miss 300 MB. Since its a small box with three drives in it, cooling is tight. I would guess that you may have an increased risk of drive failure because of it. With 3-way raid1 for /boot and either three-way raid1 or a mirrord LV if told to mirror to all three drives, your whole system is protected from one drive failure and your / and /boot are protected from two drive failures. > > Partition 2: 3-way raid1 300 MB for / > again not sure why the 3 way, currently i give 10G for this 300 MB for / is pleanty if you put all the usual mount points on mirrored LVs. > nice idea to break up into little pv > > > > Of course, performance won't be as good as if you had 4 drives so > > that you didn't have more than one busy md per drive, but this is a > > good compromise. > > > > Why is it that you can't fit in a 4th drive? Are there only 3 bays? > its a shuttle case, it only has bays for 2 hard drives, I suppose I How do you fit in three drives plus a DVD then? > could remove the dvd drive, but I use it a lot, so 3 is the magic > number, and it worked well for me, whilst I was a raid 5 guy, but it I > am thinking more back to raid1, but I would like to make the decision > to mirror or not at lvcreate time not underneath > > been playing with some HP eva's and I like being able to set the raid > level at the lun level > > > > What about an external bay that operates at SATA speeds; look at > > addonics. Doug. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
