[DRBD-user] DRBD promoting inconsistent disk?

Robert Heinzmann Robert.Heinzmann at elconas.de
Fri Aug 1 08:19:19 CEST 2008

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

Rule of thumb: Your data is garbage, verify your data and run

a) verify
b) invalidate on the bad side to trigger a full sync.

There is only one point where your data is no garbage altought no full 
sync has happened and that is when you freshly created a drbd device 
WITHOUT existing data (totally new setup). When you create the DRBD and 
add a FileSystem on top, all file system relevant blocks are replicated 
to both machines on write so this part - the only part containing valid 
data - is sync. The gutter around the file system blocks are not in 
sync, but they don't matter anyhow - However you will run into problems 
with the verify feature, because it will detect bad blocks. This is also 
true for skipping the initial sync.

Regarding initial sync you can check out 
http://drbd-plus.linbit.com/examples:skip-initial-sync on how to skip 
initial sync. I usually "null" the devices prior to doing so, to avoid 
verify problems later.

Verify does not use a tri state model (as far as I know) to 
differentiate between used and unsused blocks and only mark used+dirty 

Alireza Nematollahi schrieb:
> Hello,
> When disk state is marked as inconsistent by DRBD (i.e. when the 
> primary fails during the initial sync, secondary’s disk remains 
> inconsistent). I promoted the secondary and now it’s my primary. So, 
> here’s the question. How dangerous is this to make a server with 
> inconsistent disk as the primary? Is the data really unusable when the 
> disk is marked as inconsistent or is it just a safety feature?
> Thanks
> ------------------------------------------------------------------------
> _______________________________________________
> drbd-user mailing list
> drbd-user at lists.linbit.com
> http://lists.linbit.com/mailman/listinfo/drbd-user

Robert Heinzmann

| elconas - enterprise linux consulting and support |
| --                                                |
| Dipl.-Ing. (BA) Robert Heinzmann                  |
| ( LPIC1, LPIC2, LPIC3 certified)                  |
| Schnorrstrasse 32, 01069 Dresden                  |
| fon:   +49 (351) 2644 742 - 1                     |
| fax:   +49 (351) 2644 742 - 9                     |
| web:   http://www.elconas.de                      |
| email: Robert.Heinzmann at elconas.de                |
| USt-IdNr.: DE259053793                            |

More information about the drbd-user mailing list