[Linux-cluster] Node lag

[Frank Schliefer]

Hi,

after setting up an four node cluster we have one node that is way 
slower than the other 3 nodes.

We using eg. tiotest for benchmarking the GFS.

Normal Node:
Tiotest results for 4 concurrent io threads:
,----------------------------------------------------------------------.
| Item                  | Time     | Rate         | Usr CPU  | Sys CPU |
+-----------------------+----------+--------------+----------+---------+
| Write          40 MBs |    0.2 s | 227.426 MB/s |  36.4 %  | 384.4 % |
| Random Write   16 MBs |    0.1 s | 143.405 MB/s |  58.7 %  | 146.9 % |
| Read           40 MBs |    0.0 s | 2558.199 MB/s | 307.0 %  | 1228.0 % |
| Random Read    16 MBs |    0.0 s | 2685.169 MB/s | 550.0 %  | 1374.9 % |
`----------------------------------------------------------------------'


Slow Node:
Tiotest results for 4 concurrent io threads:
,----------------------------------------------------------------------.
| Item                  | Time     | Rate         | Usr CPU  | Sys CPU |
+-----------------------+----------+--------------+----------+---------+
| Write          40 MBs |    1.4 s |  27.687 MB/s |   2.2 %  | 121.8 % |
| Random Write   16 MBs |    4.2 s |   3.695 MB/s |   0.0 %  |   7.9 % |
| Read           40 MBs |    0.0 s | 2228.288 MB/s |  89.1 %  | 1337.1 % |
| Random Read    16 MBs |    0.0 s | 2252.739 MB/s | 230.7 %  | 692.1 % |
`----------------------------------------------------------------------'

any hints why this could happen ??

Using kernel 2.6.15.2 (sorry no RH)

besides that the cluster runs very stable !

best regards

-- 
----

Frank Schliefer