[DRBD-user] generation identifiers

FDS | Forensik Data Services office at fds.at
Fri Sep 6 15:06:13 CEST 2013

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

Hi there,


I am involved in the aftermath of a split brain event (drbd 8.3.8). log
files have given us several entries for drbd_sync_handshakes:


1.       Feb 28 07:10:04 san02 kernel: [ 1435.507176] block drbd1: self
bits:28397184 flags:0

2.       Feb 28 07:10:04 san02 kernel: [ 1435.507472] block drbd0: self
bits:225135 flags:0

3.       Feb 28 07:11:36 san01 kernel: [4427691.562720] block drbd1: self
bits:3072 flags:0

4.       Feb 28 07:11:36 san01 kernel: [4427691.562923] block drbd0: self
bits:53722300 flags:0

5.       Feb 28 07:17:46 san02 kernel: [ 1897.442652] block drbd0: self
bits:21858 flags:0

6.       Feb 28 07:17:46 san02 kernel: [ 1897.443239] block drbd1: self
bits:24262845 flags:0

7.       Feb 28 07:19:19 san01 kernel: [4428153.502129] block drbd0: self
bits:49588595 flags:0

8.       Feb 28 07:19:19 san01 kernel: [4428153.502363] block drbd1: self
E9797096C25A015C:0000000000000000:AD2868A6C65F20AA:D5016EA9D8E57175 bits:0


The Cluster consists of 2 nodes (san01 und san02) with two block devices
(drbd01 und drbd02) running in dual primary with OCFS2.


Analyzing Generation Identifiers oft he first handshake:

·         Current UUIDs (1.-4.) differ due to split brainsituation.

·          BitMap UUIDs (1.-4.) are nearly identical. Only the last digit
differs from A-D. First Historical UUIDs (1.-4.) with drbd1 are identical
but differ for block drbd0. Again only the last digit (2 vs 3).

·         Second Historical UUID (1.-4.) for both block-Devices are
identical meaning both devices have the same data set, or?



·         Reason and meaning for differing last digit UUIDs are unknown. No
information in the doc.

·         How can I see when the data sets were sync for the last time?

·         Meaning of values for flags fe 0 or 2?

·         Is it possible to decide which resource (drbd0 or drbd1) was
primary by comparing UUIDs?

Aprecciating your help.


Mit freundlichen Grüßen
Ing. Mag. Horst Greifeneder


FDS | Forensik Data Services.

Better secure than sorry!


Schenkelbachweg 32. A - 4600  W e l s.
tel. 07242. 777 15. fax. 07242. 777 16.
 <mailto:office at fds.at> mailto:office at fds.at


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