[Samba] gencache.tdb size and cache flush

[Ralph Böhme]

On Thu, Aug 30, 2018 at 11:08:55AM +0200, Peter Eriksson via samba wrote:
>> > # tdbtool gencache.tdb check
>> > Database integrity is OK and has 495309 records
>>
>> > # tdbtool gencache.tdb keys | egrep IDMAP/ | wc -l
>> >    88974
>> > # tdbtool gencache.tdb keys | egrep RA/ | wc -l
>> >   406311
>>
>> (The number of IDMAP records I sort of can understand - our AD server 
>> contains some 100k users). But 406k RA records?
>>
>> > # tdbtool gencache.tdb dump | egrep -A4 RA/ | sed -e 's:/: :' | awk '($1 == 
>> > # "[000]") {print $20}'|sort|uniq -c
>> > 2001 OSX
>> > 374245 Sam
>> > 30080 Vis
>>
>> (“VIs” = Vista, “Sam” = Samba). 374245 “Samba” records seems a bit 
>> excessive. Our servers are mostly serving Windows 7 and Windows 10 
>> clients. The most active “Samba” clients should be our Nagios monitoring 
>> system...
>
>On one of our servers right now (gencache.tdb deleted at 7am, it’s now 11am):
>
>> root at filur01:/var/samba/cache # tdbtool gencache.tdb check
>> Database integrity is OK and has 14768 records.
>
>> root at filur01:/var/samba/cache # tdbtool gencache.tdb dump | egrep -A4 RA/ | 
>> sed -e 's:/: :' | awk '($1 == "[000]") {print $20}' | sort | uniq -c
>>  328 OSX
>> 1171 Sam
>>   84 Vis
>
>
>The “Sam” count is continuously growing for every time I rerun that command 
>(like 5-10 records per minute right now). The other counters go up/down with 
>the number of clients connecting. Right now that server has some 390 SMB 
>clients (mostly Windows 10) connected.

looks like arch caching based on client GUID as record key is inflating 
gencache.

Two options: rip out arch caching or add an option that makes arch caching 
configurable.

Oh, what a mess...

-slow

-- 
Ralph Boehme, Samba Team       https://samba.org/
Samba Developer, SerNet GmbH   https://sernet.de/en/samba/
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