LVM
in [Debian]
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From: David Baron on 15 Jun 2010 09:40 LVM is a dandy tool, especially after having juggled partitions trying to shoehorn stuff on my not-so-large HDs. Unfortunately, it is a layer between the usual data tools and the data. What is needed is a LVM data/directory mapping tool that can be niced away and croned. Some way of extracting data "raw" from LVM volumes could be devised based on this map, I think. Backups? Should be done. Unfortunately, not always possible without contiguous space for intermediate storage for the backup medium, i.e. 4gig for a DVD. Offsite backups are crippled by upload speed limitations of internet providers. One must simply spring for that multi-terra USB or NAT and hope the job ever finishes. -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/201006151606.45446.d_baron(a)012.net.il
From: Boyd Stephen Smith Jr. on 15 Jun 2010 11:50 On Tuesday 15 June 2010 04:52:10 Stan Hoeppner wrote: > Boyd Stephen Smith Jr. put forth on 6/14/2010 10:45 AM: > > On Monday 14 June 2010 03:11:56 Gerald C.Catling wrote: > >> Hi Guy's, > >> I am not a Debian user but I have seen references to LVM here. > >> I have 3 drives LVM'd to give me 1.3TB of storage space on my server. > >> The first drive of this set has died. > > > > Mostly, when one of your physical volumes is irrecoverably lost, so is > > any logical volume whose logical extents corresponded to one of the lost > > physical extents. > > This is why one should only use LVM on top of real hardware or software > RAID or a big SAN LUN. You should use LVM on top of whatever you have. It's vastly superior to partitioning as a way to divide a disk. Even if you do not need to divide a disk, the adds snapshotting and an on-line migration path above just using the disk. That said, any data you care about should have some form of single-disk redundancy (at least) AND a backup plan. > Using LVM for what most in the IT world have > typically called "disk spanning", which has been around for over 2 > decades, is a recipe for trouble in the absence of a good backup/recovery > procedure, as the OP has unfortunately discovered. My introduction to LVM was partially on Linux, where the disk spanning capabilities are the most talked about feature, but also some from the HP-UX side, where we used LVM for handling the mirroring of drives, instead of a separate RAID sub-system or card. I think the Linux LVM documentation is fairly clear that a VG will not normally activate unless all its member PVs are available. > mirroring them with mdadm. I also recommend using mdadm to manage your RAID. I've had it handle 0, 1, and 5 quite well. It also supports RAID 6 and some exotic variants on RAID 1/0. -- Boyd Stephen Smith Jr. ,= ,-_-. =. bss(a)iguanasuicide.net ((_/)o o(\_)) ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-' http://iguanasuicide.net/ \_/
From: Boyd Stephen Smith Jr. on 15 Jun 2010 12:00 On Monday 14 June 2010 17:27:32 Gerald C.Catling wrote: > At what point and how do I insert -P in the lvm system? 8 replies in the thread, and only one tells you even one place to look? Little bit of topic-drift here on debian-user, I guess. The following commands support operating in --partial mode: pvscan pvs vgscan vgs vgdisplay vgchange vgcfgbackup lvscan lvs lvdisplay lvchange I ran this command to get that information: for lvmc in /sbin/lv* /sbin/pv* /sbin/vg*; do if $lvmc --help | grep -qe '--partial'; then echo $lvmc fi done 2>/dev/null -- Boyd Stephen Smith Jr. ,= ,-_-. =. bss(a)iguanasuicide.net ((_/)o o(\_)) ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-' http://iguanasuicide.net/ \_/
From: Boyd Stephen Smith Jr. on 15 Jun 2010 12:50 On Tuesday 15 June 2010 10:52:54 martin f krafft wrote: > also sprach Boyd Stephen Smith Jr. <bss(a)iguanasuicide.net> [2010.06.15.1744 +0200]: > > > mirroring them with mdadm. > > > > I also recommend using mdadm to manage your RAID. I've had it handle 0, > > 1, > > 0 is not a RAID level. Don't do it. Use LVM for that. It is a RAID level, now. It wasn't in the original paper since it lacks the *R* in RAID--Redundancy. LVM can also do striping, but it can't non-orthogonally combine it with RAID 1 to give me RAID 1/0. On the other hand, LVM striping is per-LV. Doing something like that with mdadm is... complex. -- Boyd Stephen Smith Jr. ,= ,-_-. =. bss(a)iguanasuicide.net ((_/)o o(\_)) ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-' http://iguanasuicide.net/ \_/
From: Andrew Sackville-West on 15 Jun 2010 14:50 On Tue, Jun 15, 2010 at 03:56:51PM +1000, Gerald C.Catling wrote: > On Tuesday, June 15, 2010 10:25:56 am Andrew Sackville-West wrote: > > On Tue, Jun 15, 2010 at 08:27:32AM +1000, Gerald C.Catling wrote: > > > Hi Boyd, > > > At what point and how do I insert -P in the lvm system? > > > > man lvchange > > > > > Many thanks to all respondents, and NO I did not have a backup, no drive > > > big enough to hold all data. > > > > um... really? I've heard all sorts of reasons for not making backups, > > but that is *definitely* not a valid reason. (hint, there is no valid > > reason other than "The loss of this data does not matter", which > > suggests the questions "then why do you have the data?"). > > > > There are many many ways to make take backups beyond having a disk big > > enough to hold the data. > > [...] > One good reason is that I am 73 coming on 4 and pensions are not sufficient to > support my buying larger HDD's. > I do appreciate the effort you and others have put into your replies. But it > does seem to me that all the data is lost! I suspect your data is indeed, in general, lost. You may be able to recover some of it from the portions of the logical volumes that are on the remaining partitions, but it won't be easy (and I'm in no position to tell you how to do it, sorry). As to the other, it's unfortunate that you have more data (I'm assuing you have that much data) than you can afford to backup. In that case, you are definitely running a risk of losing that data and there's not much you can do about it. If it's reasonably cost effective for you, then the static portions of the data can be written to optical disks and archived (being sure to rotate those regularly as they go bad over time). However, if you aren't really using all that 1.3TB (or whatever amount of space it was) then pull one of those drives and stick it in an USB enclosure and use it for backups. Having ~700GB of data with the most critical ~400GB backed up is definitely preferable than no backup, IMO. But it really depends on how much data you have! A
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