Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Mon, 2005-10-24 at 05:08 +0300, Louai Al-Awami wrote: > I am new to DRBD and have some questions. Welcome! > 1. I am using DRBD under UML, and I am not sure which block > device to use for the "disk" field for my resource. I use the > disk I found when running df command, but I got a message > saying "low level device already mounted". Here is my > drbd.conf: It means just what it says. /dev/ubd/disc0/disc is mounted and DRBD cannot access it until you unmount it. Once you turn on DRBD on that device *never* mount it directly again. Bad Things(tm) will happen. Use /dev/drbd/0 instead. Please make sure you understand the difference. /dev/drbd/0 is mirrored, /dev/ubd/disc0/disc is not. > 1. Is DRBD used only to synchronize the whole disk? Can not I > used to synchronize directories instead? DRBD mirrors a block device. It knows nothing about files and directories, just the raw block data that is used to represent them. So the answer is no, you can't synchronize a directory. But, you can create multiple partitions and synchronize those. So instead of one partition at /home you could have /home/user1, /home/user2, /home/user3, etc. That of course would have its own set of ramifications which you would certain want to consider. LVM may also help you. > 1. What is the meta-disk for? And can I use a meta-disk that is > smaller than 128MB? Meta data basically keeps track of which parts of the data disk are in sync. Here's an example. Say your secondary goes offline. The primary continues running and keeps track of which blocks are changed so that only those blocks have to be sent over to the secondary when it returns. Let's say the world collapses and the primary goes down too. If that list of changed blocks was only stored in RAM (as was the case in 0.6, IIRC), the primary has to do a full sync (send all data) over to the secondary. With meta data it can read the list from disk and send only the differences it would have sent had it never gone offline. Make sense? Meta data is a Good Thing(tm). While we're on the subject, I'll recommend using external meta data. Internal works just fine if you plan ahead and keep your head about you at all times, but I can't say I always think straight at 2 am. Or in the middle of the day, for that matter. I avoid internal meta data wherever possible. Corey -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 189 bytes Desc: This is a digitally signed message part URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20051023/dec82d45/attachment.pgp>