Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Sun, Jan 18, 2009 at 09:24:51PM +0100, Ekkard Gerlach wrote: > * Tomasz Chmielewski schrieb: > > > Papp Tamas schrieb: > > >Ekkard Gerlach wrote: > > >>Can I write to the according lv-device when DRBD is stopped by > > >>"drbdadm down /dev/drbd1" > > >>and lv is mounted by 'mount /dev/vg-ford2/vserver-home /mnt' without > > >>data corruption? - > > >>DRBD is set up on logical volumen! > > >> > > > > > >Of course not. > > > > It's enough to mount the device (without writing any "real files") to > > make it inconsistent with DRBD metadata. > > OK, thx. But if this device on a separate harddisk is NEVER in use with DRBD? - Its used > only if my system with 2 nodes crashes completely, when I need a copy to build a complete new > DRBD-system! For this case once again my question: if I write to that device on a separate > harddisk partition (that was formatted originally as DRBD-device) - is that device > usable for a NEW DRBD-system where this harddisk is primary from beginning/ the start? > > > Perhaps you don't understand my aim. Background what I want: > ============================================================== > node2 of my DRBD-system has only ONE harddisk, node1 has 2 disks > in soft-raid1. node2 is only a emergency and backup node. > The second harddisk of node2 is a standalone disk with backup > of the last day. Every night data ist rsync'ed to that second harddisk: > > node2:~>hb_standy all # not necessary, node2 is always secondary on all vservers > node2:~>drbdadm down all > node2:~>mount -o ro /dev/vg-ford2/vserver-home /to_sync-ro though "unexpected", even ro mount will modify the device (replay journal, update superblock, etc). rather use a snapshot. lvcreate -s -n vserver-home-snap -L 1G vg-ford2/vserver-home and access that. then you not even need to stop drbd before. though it still may be useful to disconnect drbd temporarily, as snapshots can have a heavy performance impact, which would propagate back to the Primary volume. > node2:~>rsync -aHx /to_sync-ro ==> my second harddisk > node2:~>drbdadm up all > > The second harddisk is a dd-copy of the first one of node2! > I changed UUID of physical volume and volume group and > renamed volume group of the second harddisk. Now I have a entirely redundant > harddisk for node2. Do you understand me now? > > Only one logical volume carries user data that changes every day and I want > to update my second harddisk every night. So I've two benefits: > * data from yesterday. Perhaps for restoring lost (deleted) or corrupted files > * a complete harddisk build a new DRBD-system if my running system crashes. > > ==> once again my question: can I update my second emergency and last-day-backup > harddisk every night without data corruption? whenever you bypass DRBD, you need a full sync afterwards. so don't do that, unless you know you need the full sync anyways. -- : Lars Ellenberg : LINBIT | Your Way to High Availability : DRBD/HA support and consulting http://www.linbit.com DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. __ please don't Cc me, but send to list -- I'm subscribed