Dead space in sessionid.tdb

[Volker Lendecke]

On Fri, Aug 22, 2014 at 06:22:21PM +0530, Shilpa K wrote:
> Hello,
> 
> We have a problem with sessionid.tdb where it has grown to a large size:
> 
> # ls -l sessionid.tdb
> -rwxrwxrwx  1 root  wheel  1618509824 Aug 12 14:48 sessionid.tdb
> 
> But it does not occupy much disk space.
> 
> tdbtool "info" command shows that there is one dead record of huge size:
> 
> tdb> info
> Size of file/data: 1618509824/160681
> Number of records: 101
> Smallest/average/largest keys: 14/14/15
> Smallest/average/largest data: 1576/1576/1576
> Smallest/average/largest padding: 401/401/402
> Number of dead records: 1
> Smallest/average/largest dead records: 1618305000/1618305000/1618305000
> Number of free records: 1
> Smallest/average/largest free records: 464/464/464
> Number of hash chains: 131
> Smallest/average/largest hash chains: 5/13/22
> Number of uncoalesced records: 0
> Smallest/average/largest uncoalesced runs: 0/0/0
> Percentage keys/data/padding/free/dead/rechdrs&tailers/hashes:
> 0/0/0/0/100/0/0
> 
> tdbtool "check" command shows that most of the space occupied by the TDB is
> dead space:
> 
> tdb> check
> Dead space at 204800-1618509824 (of 1618509824)
> Hashes do not match records
> Integrity check for the opened database failed.
> 
> 
> In the freelist, one of the record is of big size too:
> 
> tdb> free
> freelist top=[0x604e2420]
> entry offset=[0x604e2420], rec.rec_len = [0x00000fa8 (4008)] (end =
> 0x604e33c8)
> entry offset=[0x6046e1a0], rec.rec_len = [0x000007c8 (1992)] (end =
> 0x6046e968)
> entry offset=[0x604e0c80], rec.rec_len = [0x00000fa8 (4008)] (end =
> 0x604e1c28)
> entry offset=[0x6046ca00], rec.rec_len = [0x00000fa8 (4008)] (end =
> 0x6046d9a8)
> entry offset=[0x4d2d3000], rec.rec_len = [0x131999e8 (320444904)] (end =
> 0x6046c9e8)
> entry offset=[0x000002b8], rec.rec_len = [0x000001d0 (464)] (end =
> 0x00000488)
> total rec_len = [0x1319d278 (320459384)]
> 
> 
> Could you please let me know what are the possible circumstances which can
> lead to dead space in a TDB?

This could be the recovery area that will be created during
a tdb_repack, whatever calls that.

What version are you running? We've been fixing a few bugs
in that area in the last year or so.

With best regards,

Volker Lendecke

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