begin quoting Carl Lowenstein as of Mon, Dec 10, 2007 at 10:31:43PM -0800: > On Dec 10, 2007 5:14 PM, SJS <[EMAIL PROTECTED]> wrote: > > begin quoting Gus Wirth as of Mon, Dec 10, 2007 at 02:09:49PM -0800: > > > SJS wrote: [snip] > > > > Hm... > > > > > > > > Let's say I have 3 disks and 1 CDROM drive and two IDE channels. > > > > > > > > I want to upgrade one of the disks. > > > > > > > > So... without LVM, it's simple. I pull the CDROM, drop in the disk, > > > > partition, format, mount, and play with tar or rsync, modify fstab, > > > > pull the old disk, move the new disk, reconnect the CDROM, and bob's > > > > your uncle. > > > > > > > > With LVM, is it even simpler? > > > > > > Yes. But you have to have empty space beforehand to allocate. Or you > > > have to do some gyrations to shrink a filesystem that has excess space > > > in order to reallocate it to the filesystem that needs it. Answers at > > > <http://www.tldp.org/HOWTO/LVM-HOWTO/index.html> > > > > Specifically, > > > > http://www.tldp.org/HOWTO/LVM-HOWTO/removeadisk.html > > > > ...although it seems to require my changing where the CD-ROM drive > > connects into the IDE chain(s). I would not consider this a _good_ > > solution to the single most common disk-space problem I've ever had. > > That's only if you don't have another place to connect the extra drive.
Yes. That was my hypothetical formulation. It's also the most common situation, as if I had an unused connector, I'd just add the drive and be done with it. It's when you run out of a resource that things get interesting. With SCSI, it seemed what I ran out of was places to plug in the devices. (And with 4 computers on my KVM, I'm running into that problem as well... too many external devices, all with their own cables and wallwarts.) Firewire is even more fun than SCSI this way. > > Hm. Given TWO disks, it might be simpler. Connect spare disk #1, pvmove > > everything off the disk-to-be-replaced, vgreduce out the > > disk-to-be-replaced, pull disk-to-be-replaced, connect spare disk > > #2, pvmove everything off of spare disk #1 on to spare disk #2, > > vgreduce out spare disk #1, and you're done with nary a tar nor > > rsync in sight. > > > > Although tar or rsync might be faster than all that pvmoving. > > > > (And if you're backing up everything anyway... would restoring be faster?) > > It seems to me that the above gyrations are logically equivalent to > the classic approach: > 1) Dump from old drive to intermediate storage medium. > 2) Restore to new drive from intermediate storage. Yup. Advantage of backup-and-restore-to-larger-device is (could be) that you "defragment" the disk. Not that it's really important to do that... > I seem to remember something like this from 6th Edition Unix in a > discussion of how to increase the size of a file system. > > Of course nowadays the intermediate storage would be another disk > drive rather than magtape. Yup. -- Quick! Suggest a new sig scheme. Time is running out! Stewart Stremler -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
