* [linux-lvm] software RAID over LVM @ 2002-01-29 17:37 lvm 2002-01-29 17:40 ` Austin Gonyou 2002-01-29 17:53 ` Kirby C. Bohling 0 siblings, 2 replies; 8+ messages in thread From: lvm @ 2002-01-29 17:37 UTC (permalink / raw) To: linux-lvm Hi all, I understand the use of LVM over software RAID. But is it possible to use software RAID ON TOP of LVM? For example, have a RAID-1 mirroring array created from two logical volumes. I've tried and it seems to be working. Is it safe to do this? Any pitfalls? Thanks! Paul _______________________________________________________ The FREE service that prevents junk email http://www.mailshell.com ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [linux-lvm] software RAID over LVM 2002-01-29 17:37 [linux-lvm] software RAID over LVM lvm @ 2002-01-29 17:40 ` Austin Gonyou 2002-01-29 17:53 ` Kirby C. Bohling 1 sibling, 0 replies; 8+ messages in thread From: Austin Gonyou @ 2002-01-29 17:40 UTC (permalink / raw) To: linux-lvm [-- Attachment #1: Type: text/plain, Size: 1023 bytes --] I believe it should be possible to make an md device of lv's. On Tue, 2002-01-29 at 17:37, lvm@agilecat.mailshell.com wrote: > Hi all, > > I understand the use of LVM over software RAID. > But is it possible to use software RAID ON TOP > of LVM? For example, have a RAID-1 mirroring > array created from two logical volumes. > > I've tried and it seems to be working. Is > it safe to do this? Any pitfalls? > > Thanks! > > Paul > > _______________________________________________________ > The FREE service that prevents junk email http://www.mailshell.com > > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html -- Austin Gonyou Systems Architect, CCNA Coremetrics, Inc. Phone: 512-698-7250 email: austin@coremetrics.com "It is the part of a good shepherd to shear his flock, not to skin it." Latin Proverb [-- Attachment #2: This is a digitally signed message part --] [-- Type: application/pgp-signature, Size: 232 bytes --] ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [linux-lvm] software RAID over LVM 2002-01-29 17:37 [linux-lvm] software RAID over LVM lvm 2002-01-29 17:40 ` Austin Gonyou @ 2002-01-29 17:53 ` Kirby C. Bohling 2002-01-29 22:59 ` Austin Gonyou 1 sibling, 1 reply; 8+ messages in thread From: Kirby C. Bohling @ 2002-01-29 17:53 UTC (permalink / raw) To: linux-lvm Paul, I haven't done it. I have done mirrors underneath, but I am curious what is the reasoning and/or application. The only thing I can think up is so you can migrate your mirrors to faster drives easily. However, putting the mirror underneath should allow you to move off one mirror onto another. I don't believe that mirroring can be expanded like a filesystem can. In order to make the mirror bigger, you have to break the mirror as far as I know. So what are you planning on doing with it, or is it just "to see if it could be done". Thanks, Kirby lvm@agilecat.mailshell.com wrote: > Hi all, > > I understand the use of LVM over software RAID. > But is it possible to use software RAID ON TOP > of LVM? For example, have a RAID-1 mirroring > array created from two logical volumes. > > I've tried and it seems to be working. Is > it safe to do this? Any pitfalls? > > Thanks! > > Paul > > _______________________________________________________ > The FREE service that prevents junk email http://www.mailshell.com > > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [linux-lvm] software RAID over LVM 2002-01-29 17:53 ` Kirby C. Bohling @ 2002-01-29 22:59 ` Austin Gonyou 2002-01-30 3:44 ` Luca Berra 2002-01-30 11:50 ` Kirby C. Bohling 0 siblings, 2 replies; 8+ messages in thread From: Austin Gonyou @ 2002-01-29 22:59 UTC (permalink / raw) To: linux-lvm [-- Attachment #1: Type: text/plain, Size: 2207 bytes --] I can think of MANY uses for this. The main one would be a relatively cheap way of making a RAID0+1, or stripe of mirrors. If you don't have any hardware to do this with, then software is next. It'd be nice to be able to do this, for sure. You could even do 0+5, or something crazy like that too. On Tue, 2002-01-29 at 17:50, Kirby C. Bohling wrote: > Paul, > > I haven't done it. I have done mirrors underneath, but I am > curious what > is the reasoning and/or application. The only thing I can think up is > so you can migrate your mirrors to faster drives easily. However, > putting the mirror underneath should allow you to move off one mirror > onto another. > > I don't believe that mirroring can be expanded like a filesystem > can. In > order to make the mirror bigger, you have to break the mirror as far as > I know. So what are you planning on doing with it, or is it just "to > see if it could be done". > > Thanks, > Kirby > > lvm@agilecat.mailshell.com wrote: > > Hi all, > > > > I understand the use of LVM over software RAID. > > But is it possible to use software RAID ON TOP > > of LVM? For example, have a RAID-1 mirroring > > array created from two logical volumes. > > > > I've tried and it seems to be working. Is > > it safe to do this? Any pitfalls? > > > > Thanks! > > > > Paul > > > > _______________________________________________________ > > The FREE service that prevents junk email http://www.mailshell.com > > > > _______________________________________________ > > linux-lvm mailing list > > linux-lvm@sistina.com > > http://lists.sistina.com/mailman/listinfo/linux-lvm > > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html > > > > > > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html -- Austin Gonyou Systems Architect, CCNA Coremetrics, Inc. Phone: 512-698-7250 email: austin@coremetrics.com "It is the part of a good shepherd to shear his flock, not to skin it." Latin Proverb [-- Attachment #2: This is a digitally signed message part --] [-- Type: application/pgp-signature, Size: 232 bytes --] ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [linux-lvm] software RAID over LVM 2002-01-29 22:59 ` Austin Gonyou @ 2002-01-30 3:44 ` Luca Berra 2002-01-30 11:05 ` Austin Gonyou 2002-01-30 11:50 ` Kirby C. Bohling 1 sibling, 1 reply; 8+ messages in thread From: Luca Berra @ 2002-01-30 3:44 UTC (permalink / raw) To: linux-lvm Well, since the whole point of having LVM is ease of resizing logical volumes, and resizing MD device is impossible or painful, i do not really understand why should anyone want to do this. If mirroring were to be implemented over lvm, it should be at the PE/LE level, in the LVM driver itself, since this is not true (search archives for the reasoning behind this) the only sensible chance is having LVM over MD. On Tue, Jan 29, 2002 at 10:58:26PM -0600, Austin Gonyou wrote: > I can think of MANY uses for this. The main one would be a relatively > cheap way of making a RAID0+1, or stripe of mirrors. If you don't have > any hardware to do this with, then software is next. It'd be nice to be > able to do this, for sure. You could even do 0+5, or something crazy > like that too. -- Luca Berra -- bluca@comedia.it Communication Media & Services S.r.l. /"\ \ / ASCII RIBBON CAMPAIGN X AGAINST HTML MAIL / \ ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [linux-lvm] software RAID over LVM 2002-01-30 3:44 ` Luca Berra @ 2002-01-30 11:05 ` Austin Gonyou 0 siblings, 0 replies; 8+ messages in thread From: Austin Gonyou @ 2002-01-30 11:05 UTC (permalink / raw) To: linux-lvm [-- Attachment #1: Type: text/plain, Size: 1602 bytes --] Right, that's what I'm talking about. If you didn't do it that way, you'd be screwed! :) On Wed, 2002-01-30 at 03:43, Luca Berra wrote: > Well, since the whole point of having LVM is ease of resizing logical > volumes, > and resizing MD device is impossible or painful, i do not really > understand > why should anyone want to do this. > If mirroring were to be implemented over lvm, it should be at the PE/LE > level, > in the LVM driver itself, since this is not true (search archives for > the reasoning > behind this) the only sensible chance is having LVM over MD. > > On Tue, Jan 29, 2002 at 10:58:26PM -0600, Austin Gonyou wrote: > > I can think of MANY uses for this. The main one would be a relatively > > cheap way of making a RAID0+1, or stripe of mirrors. If you don't have > > any hardware to do this with, then software is next. It'd be nice to > be > > able to do this, for sure. You could even do 0+5, or something crazy > > like that too. > > > > -- > Luca Berra -- bluca@comedia.it > Communication Media & Services S.r.l. > /"\ > \ / ASCII RIBBON CAMPAIGN > X AGAINST HTML MAIL > / \ > > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html -- Austin Gonyou Systems Architect, CCNA Coremetrics, Inc. Phone: 512-698-7250 email: austin@coremetrics.com "It is the part of a good shepherd to shear his flock, not to skin it." Latin Proverb [-- Attachment #2: This is a digitally signed message part --] [-- Type: application/pgp-signature, Size: 232 bytes --] ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [linux-lvm] software RAID over LVM 2002-01-29 22:59 ` Austin Gonyou 2002-01-30 3:44 ` Luca Berra @ 2002-01-30 11:50 ` Kirby C. Bohling 2002-01-30 11:55 ` Austin Gonyou 1 sibling, 1 reply; 8+ messages in thread From: Kirby C. Bohling @ 2002-01-30 11:50 UTC (permalink / raw) To: linux-lvm Austin, Just as an aside, I have done all of those configurations with no LVM involved. RAID0+1, RAID1+0, and RAID5 on top of mirrored devices. Yes RAID1+0 isn't very smart, but we did it. It is much simpiler, and more reliable to have RAID underneath LVM. Not because LVM is unreliable, but if you forget, or don't realize both halves of a mirror got migrated to the same disks your mirror might be a lot less redundant then you believe it is. Wow, I just restated the a FAQ entry in a very poor manner... LVM didn't try to be all incompassing. It could have been, but it would have made things more complicated and duplicated a bunch of work from what I have read on this list. Kirby Austin Gonyou wrote: > I can think of MANY uses for this. The main one would be a relatively > cheap way of making a RAID0+1, or stripe of mirrors. If you don't have > any hardware to do this with, then software is next. It'd be nice to be > able to do this, for sure. You could even do 0+5, or something crazy > like that too. > > > On Tue, 2002-01-29 at 17:50, Kirby C. Bohling wrote: > >>Paul, >> >> I haven't done it. I have done mirrors underneath, but I am >>curious what >>is the reasoning and/or application. The only thing I can think up is >>so you can migrate your mirrors to faster drives easily. However, >>putting the mirror underneath should allow you to move off one mirror >>onto another. >> >> I don't believe that mirroring can be expanded like a filesystem >>can. In >>order to make the mirror bigger, you have to break the mirror as far as >>I know. So what are you planning on doing with it, or is it just "to >>see if it could be done". >> >> Thanks, >> Kirby >> >>lvm@agilecat.mailshell.com wrote: >> >>>Hi all, >>> >>>I understand the use of LVM over software RAID. >>>But is it possible to use software RAID ON TOP >>>of LVM? For example, have a RAID-1 mirroring >>>array created from two logical volumes. >>> >>>I've tried and it seems to be working. Is >>>it safe to do this? Any pitfalls? >>> >>>Thanks! >>> >>>Paul >>> >>>_______________________________________________________ >>>The FREE service that prevents junk email http://www.mailshell.com >>> >>>_______________________________________________ >>>linux-lvm mailing list >>>linux-lvm@sistina.com >>>http://lists.sistina.com/mailman/listinfo/linux-lvm >>>read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html >>> >>> >> >> >>_______________________________________________ >>linux-lvm mailing list >>linux-lvm@sistina.com >>http://lists.sistina.com/mailman/listinfo/linux-lvm >>read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html >> ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [linux-lvm] software RAID over LVM 2002-01-30 11:50 ` Kirby C. Bohling @ 2002-01-30 11:55 ` Austin Gonyou 0 siblings, 0 replies; 8+ messages in thread From: Austin Gonyou @ 2002-01-30 11:55 UTC (permalink / raw) To: linux-lvm [-- Attachment #1: Type: text/plain, Size: 3529 bytes --] I was stating that it's the way you'd want to do that. Doing otherwise would be bad. :) On Wed, 2002-01-30 at 11:48, Kirby C. Bohling wrote: > Austin, > > Just as an aside, I have done all of those configurations with > no LVM > involved. RAID0+1, RAID1+0, and RAID5 on top of mirrored devices. Yes > RAID1+0 isn't very smart, but we did it. It is much simpiler, and more > reliable to have RAID underneath LVM. Not because LVM is unreliable, > but if you forget, or don't realize both halves of a mirror got migrated > > to the same disks your mirror might be a lot less redundant then you > believe it is. Wow, I just restated the a FAQ entry in a very poor > manner... > > LVM didn't try to be all incompassing. It could have been, but > it would > have made things more complicated and duplicated a bunch of work from > what I have read on this list. > > Kirby > > > Austin Gonyou wrote: > > I can think of MANY uses for this. The main one would be a relatively > > cheap way of making a RAID0+1, or stripe of mirrors. If you don't have > > any hardware to do this with, then software is next. It'd be nice to > be > > able to do this, for sure. You could even do 0+5, or something crazy > > like that too. > > > > > > On Tue, 2002-01-29 at 17:50, Kirby C. Bohling wrote: > > > >>Paul, > >> > >> I haven't done it. I have done mirrors underneath, but I am > >>curious what > >>is the reasoning and/or application. The only thing I can think up is > > >>so you can migrate your mirrors to faster drives easily. However, > >>putting the mirror underneath should allow you to move off one mirror > >>onto another. > >> > >> I don't believe that mirroring can be expanded like a filesystem > >>can. In > >>order to make the mirror bigger, you have to break the mirror as far > as > >>I know. So what are you planning on doing with it, or is it just "to > >>see if it could be done". > >> > >> Thanks, > >> Kirby > >> > >>lvm@agilecat.mailshell.com wrote: > >> > >>>Hi all, > >>> > >>>I understand the use of LVM over software RAID. > >>>But is it possible to use software RAID ON TOP > >>>of LVM? For example, have a RAID-1 mirroring > >>>array created from two logical volumes. > >>> > >>>I've tried and it seems to be working. Is > >>>it safe to do this? Any pitfalls? > >>> > >>>Thanks! > >>> > >>>Paul > >>> > >>>_______________________________________________________ > >>>The FREE service that prevents junk email http://www.mailshell.com > >>> > >>>_______________________________________________ > >>>linux-lvm mailing list > >>>linux-lvm@sistina.com > >>>http://lists.sistina.com/mailman/listinfo/linux-lvm > >>>read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html > >>> > >>> > >> > >> > >>_______________________________________________ > >>linux-lvm mailing list > >>linux-lvm@sistina.com > >>http://lists.sistina.com/mailman/listinfo/linux-lvm > >>read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html > >> > > > > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html -- Austin Gonyou Systems Architect, CCNA Coremetrics, Inc. Phone: 512-698-7250 email: austin@coremetrics.com "It is the part of a good shepherd to shear his flock, not to skin it." Latin Proverb [-- Attachment #2: This is a digitally signed message part --] [-- Type: application/pgp-signature, Size: 232 bytes --] ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2002-01-30 11:55 UTC | newest] Thread overview: 8+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2002-01-29 17:37 [linux-lvm] software RAID over LVM lvm 2002-01-29 17:40 ` Austin Gonyou 2002-01-29 17:53 ` Kirby C. Bohling 2002-01-29 22:59 ` Austin Gonyou 2002-01-30 3:44 ` Luca Berra 2002-01-30 11:05 ` Austin Gonyou 2002-01-30 11:50 ` Kirby C. Bohling 2002-01-30 11:55 ` Austin Gonyou
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