[Linux-cluster] sudden slow down of gfs2 volume
Dil Lee
dillee1 at gmail.com
Wed Nov 11 04:55:37 UTC 2015
Thank you for your reply. Below are extra info.
GFS2 partition in question:
[root at apps03 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/SAN5020-order 800G 435G 366G 55%
/sanstorage/data0/images/order <- one that suffered from slow down
/dev/mapper/SAN5020-SNPimage 3.0T 484G 2.6T 16%
/sanstorage/data0/ShotNPrint/SNP_image
/dev/mapper/SAN5020-data0 1.3T 828G 475G 64%
/sanstorage/data0/images/album
normal nodes, copying a 200MB file to affected GFS2 partition
[root at apps01 ~]# time cp 200m.test /sanstorage/data0/images/order/
real 0m1.073s
user 0m0.008s
sys 0m0.996s
[root at apps08 ~]# time cp 200m.test /sanstorage/data0/images/order/
real 0m5.046s
user 0m0.004s
sys 0m1.398s
affected node, 1/30th the normal throughput atm.
I cannot reproduced the extreme slow down due as the problem reccurs
in strochastic manner.
but this is not rare since this week.
[root at apps03 ~]# time cp 200m.test /sanstorage/data0/images/order
real 0m30.885s
user 0m0.006s
sys 0m6.348s
affected node, writing to different export from the same SAN
storage(an IBM DS5020)
[root at apps03 ~]# time cp 200m.test /sanstorage/data0/ShotNPrint/SNP_image
real 0m2.353s
user 0m0.006s
sys 0m2.033s
[root at apps03 ~]# time cp 200m.test /sanstorage/data0/images/album
real 0m2.319s
user 0m0.010s
sys 0m1.798s
As the connection topology is single fibre pair connected to central
SAN switch in a star topology,
without any redundant path, if there are hardware issue
SAN5020-SNPimage/SAN5020-data0 should be affected too,
but that is not the case
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