Hi, Can anyone provide techniques or suggestions to improve GFS performance? The problem we have is best summarized by the output of a perl script that one of our frustrated developers has written: The script simply creates a file, then reads it, then removes it and prints out the time it takes for each of these instructions to complete. Sometimes it takes only a second to do all three, while sometimes it takes as long as 15 seconds to do these 3 simple instructions. I've run the script on all of the five GFS file systems and see the same response characteristics. I've run the script when the systems and when they are fairly quiet and still see the same issue. To summarize the environment: RH ES3 update 6 (GFS 6.0) 11 node cluster environment with 3 redundant lock managers and five GFS file systems mounted on each participating servers. The GFS file systems range from 100GB to 1.5 TB. The storage array is an EMC CX700 attached to a dual redundant SAN consisting four 2GB Brocade 3900 SAN switches. The HBA's in all servers are Qlogic qla2340's Firmware version: 3.03.14, Driver version 7.07.00 The servers are all HP DL585 64bit AMD opteron server class machines each configured with between 8GB and 32GB of memory. ..................................................................................................................................................................................................................................................... I've raised a support call with RedHat but according to their experts our configuration seems already to be set for optimum performance. RedHat provide a utility to get and set tunable gfs file systems parameters but there is next to no supporting documentation. So, is there anything I can do or am I missing something obvious that is just plainly mis-configured? Shown below is the GFS configuration summary derived from lock_gulmd -C and gfs_tool df for each file system. I'll be happy to supply any other information if it will help. Thanks to all in advance Paul McDowell lock_gulmd -C # hashed: 0x44164246 cluster { name = "cra_gfs" lock_gulm { heartbeat_rate = 15.000 allowed_misses = 3 coreport = 40040 new_connection_timeout = 15.000 # server cnt: 3 # servers = ["iclc1g.cra.applera.net", "iclc2g.cra.applera.net", "ccf001g.cra.applera.net"] servers = ["172.20.8.21", "172.20.8.22", "172.20.8.51"] lt_partitions = 4 lt_base_port = 41040 lt_high_locks = 20971520 lt_drop_req_rate = 300 prealloc_locks = 5000000 prealloc_holders = 11000000 prealloc_lkrqs = 60 ltpx_port = 40042 #gfs_tool df /crx: SB lock proto = "lock_gulm" SB lock table = "cra_gfs:cra_crx" SB ondisk format = 1308 SB multihost format = 1401 Block size = 4096 Journals = 11 Resource Groups = 1988 Mounted lock proto = "lock_gulm" Mounted lock table = "cra_gfs:cra_crx" Mounted host data = "" Journal number = 0 Lock module flags = async Local flocks = FALSE Local caching = FALSE Type Total Used Free use% ------------------------------------------------------------------------ inodes 933593 933593 0 100% metadata 943899 121868 822031 13% data 128274180 58546879 69727301 46% [root@iclc1g tmp]# gfs_tool df /crx/data /crx/data: SB lock proto = "lock_gulm" SB lock table = "cra_gfs:cra_crxdata" SB ondisk format = 1308 SB multihost format = 1401 Block size = 4096 Journals = 11 Resource Groups = 5970 Mounted lock proto = "lock_gulm" Mounted lock table = "cra_gfs:cra_crxdata" Mounted host data = "" Journal number = 0 Lock module flags = async Local flocks = FALSE Local caching = FALSE Type Total Used Free use% ------------------------------------------------------------------------ inodes 3296091 3296091 0 100% metadata 2649271 616186 2033085 23% data 385236382 310495360 74741022 81% [root@iclc1g tmp]# gfs_tool df /crx/home /crx/home: SB lock proto = "lock_gulm" SB lock table = "cra_gfs:cra_crxhome" SB ondisk format = 1308 SB multihost format = 1401 Block size = 4096 Journals = 11 Resource Groups = 3978 Mounted lock proto = "lock_gulm" Mounted lock table = "cra_gfs:cra_crxhome" Mounted host data = "" Journal number = 0 Lock module flags = async Local flocks = FALSE Local caching = FALSE Type Total Used Free use% ------------------------------------------------------------------------ inodes 3477487 3477487 0 100% metadata 3162164 341627 2820537 11% data 254032093 157709829 96322264 62% [root@iclc1g tmp]# gfs_tool df /usr/local /usr/local: SB lock proto = "lock_gulm" SB lock table = "cra_gfs:cra_usrlocal" SB ondisk format = 1308 SB multihost format = 1401 Block size = 4096 Journals = 11 Resource Groups = 394 Mounted lock proto = "lock_gulm" Mounted lock table = "cra_gfs:cra_usrlocal" Mounted host data = "" Journal number = 0 Lock module flags = async Local flocks = FALSE Local caching = FALSE Type Total Used Free use% ------------------------------------------------------------------------ inodes 765762 765762 0 100% metadata 582989 22854 560135 4% data 24393837 9477084 14916753 39% [root@iclc1g tmp]# gfs_tool df /data /data: SB lock proto = "lock_gulm" SB lock table = "cra_gfs:cra_GQ" SB ondisk format = 1308 SB multihost format = 1401 Block size = 4096 Journals = 11 Resource Groups = 1298 Mounted lock proto = "lock_gulm" Mounted lock table = "cra_gfs:cra_GQ" Mounted host data = "" Journal number = 0 Lock module flags = async Local flocks = FALSE Local caching = FALSE Type Total Used Free use% ------------------------------------------------------------------------ inodes 10026 10026 0 100% metadata 282680 189037 93643 67% data 103761726 94277221 9484505 91%