[DRBD-user] attempt to access beyond end of device

Lars Ellenberg Lars.Ellenberg at linbit.com
Sat Oct 8 05:16:33 CEST 2005

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

/ 2005-10-07 19:08:11 +0800
\ Francis I. Malolot:
> But we double check our volume,all nodes has the size
> it had all 1.5TB.See below the xfs_info of both nodes.

the xfs_info is read from the super block, which is located at the very
start of the device, and has been mirrored by drbd, so it is identical.

> data        =                          bsize=4096   blocks=384008192, 

if I just take this line,
this is 8*384008192 == 3072065536 sectors.
this is clearly _the_same_ as [A],
but clearly larger than [B] and
therefore beyond end of device (after connect).

> ok. then, your lower level devices on the two nodes are not of the same
> size, and you created the file system on the larger one.
> now they connect, and DRBD can only "export" the minimum of the device
> sizes to user space.
> let me quote from the log below:
> first creation of state block:
> > drbd0: 1536032768 KB now marked out-of-sync by on disk bit-map.
[A]        3072065536 sectors

> after handshake:
> > drbd0: 1535508480 KB now marked out-of-sync by on disk bit-map.
> these are    3071016960 sectors, which is later the "limit"
> in the "attempt ..." messages.
> > drbd0: rw=0, want=3072065536, limit=3071016960
                  [A] ^^^^^^^^^^        ^^^^^^^^^^ [B]

> whereas XFS still thinks it has 3072065536 sectors,
> and tries to use them.
> does that make sense to you?

you want to compare
 # cat /proc/partitions
 # lvs --units s
 # dmsetup table
 # ...

: Lars Ellenberg                                  Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH            Fax +43-1-8178292-82 :
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