Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
> Hi, > > With all the discussions about external/internal metadata since a few > days ago, I throw an eye to my drbd configuration. > Then I wondered why I used flexible-meta-data internal in my > configuration. > So I looked to the drbd user guide: > http://www.drbd.org/users-guide/re-drbdconf.html > > And now I'm more confused than two days ago :-) > So, what is the real difference between flexible-meta-disk and meta-disk > (internal or external) ? flexible-meta-disk means that DRBD does not allocate a fixed metadata area of 128M, but one that is roughly proportional to the DRBD device size (_up_ to 128M for a 4TB device). meta-disk means that DRBD does allocate a fixed metadata area of 128M, regardless of DRBD device size. Now brace yourself, internal metadata is _always_ flexible, "meta-disk internal" and "flexible-meta-disk internal" are equivalent. > And the cherry on the cake question is the following one: with external > meta-data, what happens if you loose the device holding the meta-data? > Are your data at risk, or does drbs can rebuild the meta-data (from the > data or peer) ? Neither. DRBD metadata is both per-device and per-node (one set of metadata for each device on each node). So if you lose your metadata, you must do "drbdadm down", replace the metadata device, then do "drbdadm create-md" anew, and bring your device up again. This inevitably necessitates a full sync from the other node (with newly-created metadata, DRBD has no way of knowing which blocks are in sync and which aren't), which will be initiated automagically upon connection. Florian -- : Florian G. Haas : LINBIT Information Technologies GmbH : Vivenotgasse 48, A-1120 Vienna, Austria Enterprise consultancy and support for DRBD is available from LINBIT. If you are interested, Please go to http://www.linbit.com/en/contact and leave your contact details. When replying, there is no need to CC my personal address. I monitor the list on a daily basis. Thank you.