Hello, where can I find information about the amount of bytes involved during a path polling based on the possible configurations? Did it changed between rh el 5.9 and rh el 6.3, that means somehow between device-mapper-multipath-0.4.7-54.el5_9.1 and device-mapper-multipath-0.4.9-56.el6.x86_64 In my case: - polling interval not set in multipath.conf for rh el 6 So it should be 5 seconds stabilized then to 20 seconds Set to 30 for rh el 5.9 - path_checker = tur for both - number of paths for every device = 8 I have my RH E 6.3 and rh el 5.9 systems connected to a netapp FAS3240 in metrocluster configuration via FC in rh el 6.3 device-mapper-multipath-0.4.9-56.el6.x86_64 An example of lun is: $ sudo multipath -l 360a9800037543544465d424130536f6f 360a9800037543544465d424130536f6f dm-15 NETAPP,LUN size=10G features='3 queue_if_no_path pg_init_retries 50' hwhandler='1 alua' wp=rw |-+- policy='round-robin 0' prio=0 status=active | |- 3:0:0:12 sdn 8:208 active undef running | |- 3:0:1:12 sdab 65:176 active undef running | |- 4:0:2:12 sdbr 68:80 active undef running | `- 4:0:3:12 sdcf 69:48 active undef running `-+- policy='round-robin 0' prio=0 status=enabled |- 4:0:0:12 sdap 66:144 active undef running |- 4:0:1:12 sdbd 67:112 active undef running |- 3:0:2:12 sdct 70:16 active undef running `- 3:0:3:12 sddh 70:240 active undef running - checks are for both active and enabled groups, correct? - path_grouping_policy is set to group_by_prio for both Is it correct to say that the enabled group should be composed by the paths towards the second head of netapp? All these questions for general knowledge and based on questions I received about my rh le 6.3 systems sending greater amount of I/O to the second head of netapp vs rh el 5.9 and VMware. Some examples from "lun stat -o" on netapp console 4 hours after a reset of counters The lun above in 6.3 /vol/ORAUGDM_UGDMPRE_RDOF_vol/ORAUGDM_UGDMPRE_RDOF (4 hours, 48 minutes, 1 second) Read (kbytes) Write (kbytes) Read Ops Write Ops Other Ops QFulls Partner Ops Partner KBytes 30604 16832724 7647 49280 47331 0 15986 10400 so about 10Mbytes and 15986 ops through the second head. At he same time another lun on a rh el 5.9 server shows 2304 operations on the other head but 0 Kbytes: /vol/ORAUGOL_UGOLPRO_CTRL_vol/ORAUGOL_UGOLPRO_CTRL (4 hours, 48 minutes, 1 second) Read (kbytes) Write (kbytes) Read Ops Write Ops Other Ops QFulls Partner Ops Partner KBytes 0 342412 0 25775 6912 0 2304 0 where the lun i of kind: $ sudo /sbin/multipath -l 360a9800037543544465d424130536671 360a9800037543544465d424130536671 dm-11 NETAPP,LUN [size=1.0G][features=3 queue_if_no_path pg_init_retries 50][hwhandler=1 alua][rw] \_ round-robin 0 [prio=0][active] \_ 8:0:1:1 sdas 66:192 [active][undef] \_ 7:0:0:1 sdc 8:32 [active][undef] \_ 7:0:1:1 sdp 8:240 [active][undef] \_ 8:0:0:1 sdx 65:112 [active][undef] \_ round-robin 0 [prio=0][enabled] \_ 7:0:2:1 sdan 66:112 [active][undef] \_ 8:0:2:1 sdbj 67:208 [active][undef] \_ 7:0:3:1 sdcc 69:0 [active][undef] \_ 8:0:3:1 sdce 69:32 [active][undef] also for bigger luns on another 5.9 server with more accesses: /vol/ORASTUD_DB1_RDOF_vol/ORASTUD_DB1_RDOF (4 hours, 48 minutes, 1 second) Read (kbytes) Write (kbytes) Read Ops Write Ops Other Ops QFulls Partner Ops Partner KBytes 26539148 30920888 120309 119041 6864 0 2288 0 So 56Gb of I/O and zero KBytes on the other head and only 2288 ops on it VMware luns stats are aligned with rh el 5.9 behavior: /vol/vmfs1a4x/vmfs1a44 (4 hours, 48 minutes, 1 second) Read (kbytes) Write (kbytes) Read Ops Write Ops Other Ops QFulls Partner Ops Partner KBytes 85351 5675378 5980 927689 13144 0 6494 0 Thanks in advance for any insight. Gianluca -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel