[Samba] Strange DB behaviour

[mathias dufresne]

Some metrics about DB filling.
Number of groups hosted in each DB:
10 members -> 216 583 groups can be injected before failure
100 members -> 14579 groups can be injected before failure
1000 members -> 1297 groups can be injected before failure

What I feel as very disappointing in all that is Samba telling me there is
no more space in DB to do anything (which is equivalent to a totally broken
domain) when there was in fact free space...


2015-07-22 15:37 GMT+02:00 mathias dufresne <infractory at gmail.com>:

> Hi all,
>
> Weeks ago, testing DB space used by groups I created 3 DC, each containing
> 120 000 users and having their own domain.
> Then I've created groups with random users, each group with the same
> number of users (10, 100 and 1000 members). LDIF files always contain 1000
> members (100 groups of 10 users, 10 of 100 members and one group for the
> last case). Finally I injected LDIF sequentially, until DB size reached its
> limit.
>
> So I abandoned these 3 DCs with an almost full DB, so 4GB each.
>
> Last days I was interesting about tombstoneLifetime, how to change it, how
> DB would react to that change etc.
>
> But prior to that I had a try about setting up a passwords to my users.
> After few (1000 to 2000) password changes DB has no free space even for a
> new password. That should have led me to play with tombstoneLifetime :)
>
> So I set up, on only one DC, a tombstoneLifetime of 1 day. Following that
> I launched a "tdbdump DC\=AD,DC\=DOMAIN,DC\=TLD | tdbrestore
> DC\=AD,DC\=DOMAIN,DC\=TLD.restored"
>
> The point is resultant file was 2.8GB (2 906 853 376 bytes) rather than
> 4GB fully filled.
>
> This was on the the DC with 100 members groups.
>
> Wondering about that behaviour, I changed tombestoneLifetime on the two
> other DC then tdbdump | tdbrestore them.
>
> On DC with 1000 members per group the result was identical: 2.1GB for
> restored DB (2 220 548 096 bytes).
> On last DC with 10 members per group restored database is still 3.7GB (3
> 935 682 560 bytes).
>
> As I never used ldbdel command on none of these DC I would have expected I
> had no deleted objects but according to these tests, it seems some objects
> were considered as deleted when adding users to groups.
>
> Is this behaviour really a functionality? (No offence meant in that
> question ;)
>
> Cheers,
>
> mathias
>
>