[lustre-discuss] how to set max_pages_per_rpc (I have done something wrong and need help)

Harald van Pee pee at hiskp.uni-bonn.de
Wed Nov 15 07:06:29 PST 2017


Dear all,

I want to set max_pages_per_rpc to 64 instead of 256
lustre mgs/mdt version 2.53
lustre oss version 2.53
lustre client 2.6

on client I have done:
lctl get_param osc.hiskp3-OST*.max_pages_per_rpc
osc.hiskp3-OST0001-osc-ffff88105dba4800.max_pages_per_rpc=256
osc.hiskp3-OST0002-osc-ffff88105dba4800.max_pages_per_rpc=256
osc.hiskp3-OST0003-osc-ffff88105dba4800.max_pages_per_rpc=256
osc.hiskp3-OST0004-osc-ffff88105dba4800.max_pages_per_rpc=256
lctl set_param osc.hiskp3-OST*.max_pages_per_rpc=64

this works, but after remount I get again 256 therefore I want to make it 
permant with
 lctl conf_param hiskp3-OST*.osc.max_pages_per_rpc=64

But I get the message, that this command have to be given on mdt
unfortunately I go to our combined mgs/mdt and get

Lustre: Setting parameter hiskp3-OST0000-osc.osc.max_pages_per_rpc in log 
hiskp3-client
LustreError: 956:0:(obd_config.c:1221:class_process_config()) no device for: 
hiskp3-OST0000-osc-MDT0000
LustreError: 956:0:(obd_config.c:1591:class_config_llog_handler()) 
MGC192.168.128.200 at o2ib: cfg command failed: rc = -22
Lustre:    cmd=cf00f 0:hiskp3-OST0000-osc-MDT0000  1:osc.max_pages_per_rpc=64  

than I can not mount client and want to go back 
lctl set_param osc.hiskp3-OST*.max_pages_per_rpc=64

Lustre: Modifying parameter hiskp3-OST0000-osc.osc.max_pages_per_rpc in log 
hiskp3-client
Lustre: Skipped 1 previous similar message
LustreError: 966:0:(obd_config.c:1221:class_process_config()) no device for: 
hiskp3-OST0000-osc-MDT0000
LustreError: 966:0:(obd_config.c:1591:class_config_llog_handler()) 
MGC192.168.128.200 at o2ib: cfg command failed: rc = -22
Lustre:    cmd=cf00f 0:hiskp3-OST0000-osc-MDT0000  1:osc.max_pages_per_rpc=256  

obviously what I have done was completly wrong and I can no longer mount a 
client, mounted clients are working.
How can I get it back working?
hiskp3-MDT0000 ist the label of the mgs/mdt but hiskp3-OST0000-osc-MDT0000
seems to be incorrect

What I have to do to get the mgs/mdt working again?
Its your production cluster 
Any help is welcome

Best 
Harald








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