Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi everybody, we're running LVM-DRBD-Xen-LVM sandwich on our boxes and got an interesting question: as you can see from above we have LV (say /dev/system/lv1) which we use as a base for DRBD device (say /dev/drbd0, named "vmspace") which is then used as a raw disk for Xen VM (say myVM). Inside of myVM we use LVM again to manage partitions etc. (say we have /dev/vmsystem VG inside with lots of various LVs in that VG). Now above we've used to be able to dynamically grow our VMs if needed. Scenario looks like this: we do lvresize /dev/system/lv1 drbdadm resize vmspace ...inside of VM fdisk /dev/xvda ...add another partition /dev/xvda3 vgextend /dev/xvda3 lvresize /dev/vmsystem/lvX resize2fs /dev/vmsystem/lvX Now another thing that happened after using above scenario: running fdisk -l /dev/system/lv1 we saw different picture on primary and secondary DRBD box until secondary was rebooted. Now the actual questions: 1. why did fdisk report /dev/system/lv1 layout different for primary and secondary (probably not-so-much DRBD question, but it kind of is related). By different I mean - it was showing the size of /dev/xvda correctly, but it was showing only 2 partitions on secondary box and 3 on primary 2. is it OK to use LVM snapshots for /dev/system/lv1 on secondary box to create "copies" of running VM to get some migration/testing done? (I realize problems about snapshoting running system, but are there any other problems)? 3. I remember seeing some information about "not touching raw devices underneath DRBD devices" and I also remember reading that even read-only mounts along with other apparently "innocent" operations still modify underlying devices. Does anybody have reference to the list of those "big no-no's" ? -- Dmitry Makovey Web Systems Administrator Athabasca University (780) 675-6245 -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 190 bytes Desc: This is a digitally signed message part. URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20090721/ca703050/attachment.pgp>