What eats up space in /var/log ?

Hi, I got this: /var/log disk usage exceeds 90%. Reduce log disk space now.

So I checked filesystem through df -lh and see this:

/dev/mapper/vg--db--vda-dat.log.1
                      6.9G  5.8G  847M  88% /var/log

When I tried to list files ordered by size, I get this:

[root@myF5box:/S2-green-P:Active:Changes Pending] log  find -type f | xargs du | sort -rn | more
98560   ./apm
21252   ./apm.5.gz
20476   ./apm.3.gz
20084   ./apm.12.gz
20068   ./apm.6.gz
19940   ./apm.13.gz
19924   ./apm.23.gz
19736   ./apm.14.gz
19480   ./apm.19.gz
19400   ./apm.15.gz
19396   ./apm.4.gz
19356   ./apm.10.gz
19104   ./apm.24.gz
18792   ./apm.16.gz
18648   ./apm.8.gz
18452   ./apm.18.gz
17984   ./apm.7.gz
17708   ./apm.11.gz
17656   ./apm.20.gz
16508   ./apm.22.gz
16360   ./apm.21.gz
16236   ./apm.1.gz
16092   ./apm.17.gz
16080   ./apm.9.gz
15924   ./apm.2.gz
9788    ./restjavad-audit.3.log
9788    ./restjavad-audit.2.log
9788    ./restjavad-audit.1.log
7120    ./restjavad-audit.0.log

My question is, how it is possible that df command says that 5.8GB is consumed, but I cannot find any files making so big consumption? The biggest file is apm which has 98MB.. not so much.

Thanks for any advice. Zdenek