Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi Dmitry, I'm using a setup very similar to yours apart from the last part - I use a 1 LV to Xen partition mapping for all of our PV domUs. Its only the HVM ones which I use as a full disk image, but anyway its not too relevant. Our backup strategy currently involves taking daily LVM snapshots and rsyncing data from them (or backing up using dd in case of HVM). Doing this means you aren't doing anything to the underlying device so removes any risk - just make sure your snapshot is big enough to cope with the amount of data that will change whilst it exists. Whenever I do a resize of a LV & subsequent DRBD device I always schedule a reboot of the domU afterwards to make sure that the OS properly picks up the resize. I've not had any problems with either of these approaches so far. On 21/07/09 22:49, Dmitry S. Makovey wrote: > 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" ? > > > > ------------------------------------------------------------------------ > > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user -- Adam Wilbraham - Systems Administrator TechnoPhobia Limited The Workstation 15 Paternoster Row SHEFFIELD England S1 2BX t: +44 (0)114 2212123 f: +44 (0)114 2212124 e: adam.wilbraham at technophobia.com w: http://www.technophobia.com/ Registered in England and Wales Company No. 3063669 VAT registration No. 598 7858 42 ISO 9001:2000 Accredited Company No. 21227 ISO 14001:2004 Accredited Company No. E997 ISO 27001:2005 (BS7799) Accredited Company No. IS 508906 Investor in People Certified No. 101507 The contents of this email are confidential to the addressee and are intended solely for the recipients use. If you are not the addressee, you have received this email in error. Any disclosure, copying, distribution or action taken in reliance on it is prohibited and may be unlawful. Any opinions expressed in this email are those of the author personally and not TechnoPhobia Limited who do not accept responsibility for the contents of the message. All email communications, in and out of TechnoPhobia, are recorded for monitoring purposes.