Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Wed, Oct 22, 2008 at 04:17:22PM +0200, Andrew McGill wrote: > On Wednesday 22 October 2008 10:13:19 Lars Ellenberg wrote: > > On Wed, Oct 22, 2008 at 09:39:43AM +0200, Andrew McGill wrote: > > > On Tuesday 21 October 2008 23:35:27 Lars Ellenberg wrote: > > > > I think in all areas drbd does better than nbd/iscsi + md raid1, > > > > but I am happy to hear all ideas, and use them as inspiration > > > > for future linux storage replication solutions. > > > > > > Inspiration. Happiness. Can try. But no promises. > > > > > > drdb cannot be a plug-in replacement for md raid1, as far as I know, > > > since two drbd peers require two systems (or some very careful > > > configuration on one system). > > > > > > It would be rather useful if one *could* replace MD RAID1 with DRBD. For > > > example, if you could replicate a disk to a USB device, you could use > > > drbd to make physical snapshots for off-line backups. You could also do > > > a large sync over a local bus, rather than the network. > > > > why would we want to do that. > Because md recovery is painful under load ... > > # cat /proc/mdstat > Personalities : [raid1] > md0 : active raid1 sdb1[0] sda1[1] > 152512 blocks [2/2] [UU] > > md1 : active raid1 sdb3[0] sda3[1] > 1959808 blocks [2/2] [UU] > resync=DELAYED > > md2 : active raid1 sdb5[0] sda5[1] > 306544192 blocks [2/2] [UU] > [=>...................] resync = 9.4% (28959168/306544192) > finish=11301.1min speed=408K/sec echo 20000 > /sys/block/md2/md/sync_speed_min ? > > we replicate _below_ the file system for a reason: > > to be file system/application agnostic. > If filesystems agnostically conspired to reserve blocks on request, you could > replicate above and below. you lost me there... if you want a replicating file system, use one (which one?) -- : 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