Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
I've got your point. I know my first message is long and maybe complicated. It seems you "jump" some lines. It's not "nested" LVM as described in the doc (because I RTFM before try to ask help). My problem is not located on DRBD hosts. I've run some test, and I can really simplify the example. Please, read this, I think it's clear now : Let's say I export a simple physical volume with DRBD. So, NO LVM in DRBD, just replicate "/dev/sdb" for example, and export it (/dev/drbd0) on each DRBD host with iSCSI. So, on ALL my clients (connected iSCSI), I saw with "fdisk -l" : Disk /dev/sdb: 2998.8 GB, 2998869356544 bytes So, my CLIENT1 connected to DRBD1, decide to create a volume group and a logical volume. Despite all my efforts (vgscan, pvscan, lvscan), CLIENT2 connected to replicated DRBD2, cannot see anything ! No VG, no LV ! Nothing ! But, if I decide to do that on DRBD2 : drbdadm disconnect ressource && drbdadm connect ressource Just after THIS, I can see all the stuff I've created on CLIENT1. So, it's NOT a question of LVM on DRBD, because in this case, I don't use it anymore. I can undestand if LVM data's on client are not replicated on each DRBD hosts, but WHY it works if I disconnect/reconnect these two ? It doesn't have any sense to me.... Thanks for your help, Regards, Olivier XO Project http://xen-orchestra.com On Sun, Mar 7, 2010 at 11:47 PM, Maros Timko <timkom at gmail.com> wrote: > 2010/3/7 Olivier LAMBERT <lambert.olivier at gmail.com>: >> Hello, >> >> cLVM doesn't provide snapshots :( > > cLVM has nothing to do with the LVM snapshots. > >> >> But you say my behaviour is "normal" ? so, why lvcreate/lvremove is >> not replicated ? it's not a "block" operation for the bottom layer ? >> And if I export a physical volume (and not a LVM one) and then after >> on iSCSI volume I do "lvcreate" does it solve the problem ? > > Your issue is where the LVM metadata is stored and how the OS could > refresh the changes (if any). > I would suggest start here, as the guys from LINBIT are really sharing > a lot of their know-how, but it gets pretty annoying to answer the > same questions every couple of months: > http://www.drbd.org/users-guide/s-nested-lvm.html > > If this will not explain it exactly, try to search on DRBD, Pacemaker > and Heartbeat user mailing lists with keyword cLVM. I am pretty sure > you will find a definite answer. > Or try to check what cLVM does and why was it created. > >> >> Regards, >> >> Olivier >> XO Project >> http://xen-orchestra.com >> >> On Sat, Mar 6, 2010 at 6:01 PM, Maros Timko <timkom at gmail.com> wrote: >>>> >>>> Message: 1 >>>> Date: Thu, 4 Mar 2010 17:48:24 +0100 >>>> From: Olivier LAMBERT <lambert.olivier at gmail.com> >>>> Subject: [DRBD-user] Detection of Logical Volume on nested LVM >>>> replication >>>> To: drbd-user at lists.linbit.com >>>> Message-ID: >>>> <f769216c1003040848m4b1ffaaatc15dc952781ce946 at mail.gmail.com> >>>> Content-Type: text/plain; charset=ISO-8859-1 >>>> >>>> Hello, >>>> >>>> I'll try to be clear, but it's really hard to explain.. >>>> In few words : when I create a Logical Volume on a host attached >>>> (iSCSI) to one DRBD server, it doesn't appear on the second host, >>>> attached to the other DRBD. But, on existing LV, it works like a charm >>>> (all data's are replicated). And more, if I create a LV on "one side", >>>> and fill it with data, I saw the replication link with heavy traffic, >>>> but always no LV. >>>> Now, to understand, here is how it happened with this infrastructure. >>>> >>>> 1) On both DRBD hosts : Debian GNU/Linux, Dual Primary setup, version: >>>> 8.3.7 (api:88/proto:86-91). I choose to configure a resource on a >>>> Logical volume of 500Gb (named /dev/vg0/xen). To be clear, two hosts >>>> are "DRBD1" & "DRBD2". a cat /proc/drbd gave this : >>>> 0: cs:Connected ro:Primary/Primary ds:UpToDate/UpToDate C r---- >>>> ns:153716 nr:408752 dw:562408 dr:355156 al:179 bm:109 lo:0 pe:0 >>>> ua:0 ap:0 ep:1 wo:n oos:0 >>>> >>>> >>>> 2) This resource is exported with iSCSI. For the example, let's say >>>> that CLIENT1 is connected to DRBD1, and CLIENT2 is connected to DRBD2. >>>> It's simplifed because in real, it's multiple Xen Dom0's clients with >>>> multipath (but we don't care of that here). >>>> >>>> 3) CLIENT1 see the device as a block device (so far so good, iSCSI >>>> works). I choose to use LVM on this block device. I create for example >>>> : /dev/vg_xen/mydisk on CLIENT1. I mount it, I put some stuff in there >>>> : I saw the replication like working : some traffic. DRBD2 and 1 says >>>> it's all OK. If I lvscan on CLIENT1, I can see my brand new volume. >>>> >>>> 4) CLIENT2, (so, connected on iSCSI with DRBD2), see the block device, >>>> the volume group, but NOT the Logical Volume. If I disconnect DRBD2's >>>> resource, and reconnect it, and reconnect iSCSI of CLIENT2, wow, I saw >>>> the LV ! >>>> >>>> And more : if the LV exists on both side (after disconnect/reconnect >>>> the resource), data's are correctly replicated (obviously, I do NOT >>>> mount LV on both side, I'm aware of that !). But, if I fill on one >>>> side (e.g CLIENT1), dismount it, then mount it on CLIENT2, data are >>>> here, without any problem. >>>> >>>> So, my "theory", is that LVM operations (lvcreate or lvremove) on a >>>> volume group, which is on top of iSCSI and LVM replicated device by >>>> DRBD, are NOT replicated, UNTIL disconnect/reconnect the ressource. I >>>> don't know why, and that's why I ask here to understand what I miss. >>> >>> Right. Discussed many times here and on Heartbeat/Pacemaker list. Try >>> to search with cLVM keyword. >>> >>>> Additional Informations: If my clients are connected to the SAME DRBD >>>> (let's tell DRBD1), if CLIENT1 creates a LV, CLIENT2 is immediatly >>>> aware of that (just inactive, not a problem, vgchange and it works). >>>> So the "problem" is during the replication. >>>> >>>> Thanks for your help. >>>> >>>> >>>> Regards, >>>> >>>> >>>> Olivier >>>> XO Project >>>> http://xen-orchestra.com >>>> >>> _______________________________________________ >>> drbd-user mailing list >>> drbd-user at lists.linbit.com >>> http://lists.linbit.com/mailman/listinfo/drbd-user >>> >> >