[dm-devel] system freeze/console flood when unplugging one path of multipath disk array

[Rainer Toebbicke]

Hello,

I've got a Sun 3510 disk array and a dual-channel Qlogic FC HBA, in a 
Sun X4100 under RHEL4 U4,  each path connected to the array over a 
qlogic 5600 switch.

The devices are seen correctly with multipath -l as far as I can judge.


When I disable one of the paths during a stress test (in this case, an 
fsck -y), the system "freezes". Actually, it just sends enough 
(thousands) error messages of the style

end_request: I/O error, dev sdb, sector 279446024
Buffer I/O error on device sdb1, logical block 279445961
lost page write due to I/O error on sdb1
SCSI error : <1 0 0 1> return code = 0x10000
end_request: I/O error, dev sdb, sector 279446025
Buffer I/O error on device sdb1, logical block 279445962
lost page write due to I/O error on sdb1
SCSI error : <1 0 0 1> return code = 0x10000
end_request: I/O error, dev sdb, sector 279446026
Buffer I/O error on device sdb1, logical block 279445963
lost page write due to I/O error on sdb1
SCSI error : <1 0 0 1> return code = 0x10000
end_request: I/O error, dev sdb, sector 279446027
Buffer I/O error on device sdb1, logical block 279445964
lost page write due to I/O error on sdb1
SCSI error : <1 0 0 1> return code = 0x10000


to the serial console to make it appear completely stuck for hours.

The fsck does not finish, BTW, it restarts from the beginning as soon 
as I re-enable the port in the switch.

root at afs26 ~]# multipath -l
mpath2 (3600c0ff0000000000a792a1887b34100)
[size=136 GB][features="1 queue_if_no_path"][hwhandler="0"]
\_ round-robin 0 [active]
  \_ 1:0:0:3  sdc 8:32  [active][ready]
  \_ 2:0:0:3  sdi 8:128 [active][ready]

mpath1 (3600c0ff0000000000a792a0aac9b4200)
[size=136 GB][features="1 queue_if_no_path"][hwhandler="0"]
\_ round-robin 0 [active]
  \_ 1:0:0:1  sdb 8:16  [active][ready]
  \_ 2:0:0:1  sdh 8:112 [active][ready]
....

/etc/multipath.conf just contains
defaults {
         default_features "1 queue_if_no_path"
         user_friendly_names yes

}

besides the usual blacklist.

Any ideas?

-- 
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Rainer Toebbicke
European Laboratory for Particle Physics(CERN) - Geneva, Switzerland
Phone: +41 22 767 8985       Fax: +41 22 767 7155