1. 문제점

 - 서비스는 정상적인데 에러 메세지가 뜸..

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Mar 17 22:38:44 NOK-DB-2 lkscsid[12268]: ERROR:lkscsid:::007058:lkscsid: SCSI Reserve failed on '/dev/sdb', result:-2, Sense Key = 6.
Mar 17 22:38:44 NOK-DB-2 lkscsid[12268]: ERROR:lkscsid:::007078:lkscsid: DEVICE FAILURE on SCSI device '/dev/sdb', RETRY. ret=-2, errno=0x16, retry count=1.
Mar 17 22:39:02 NOK-DB-2 lkscsid[12268]: ERROR:lkscsid:::007058:lkscsid: SCSI Reserve failed on '/dev/sdb', result:-2, Sense Key = 6.
Mar 17 22:39:02 NOK-DB-2 lkscsid[12268]: ERROR:lkscsid:::007078:lkscsid: DEVICE FAILURE on SCSI device '/dev/sdb', RETRY. ret=-2, errno=0x16, retry count=2.
Mar 17 22:39:38 NOK-DB-2 lkscsid[12268]: ERROR:lkscsid:::007058:lkscsid: SCSI Reserve failed on '/dev/sdb', result:-2, Sense Key = 6.
Mar 17 22:39:38 NOK-DB-2 lkscsid[12268]: ERROR:lkscsid:::007078:lkscsid: DEVICE FAILURE on SCSI device '/dev/sdb', RETRY. ret=-2, errno=0x16, retry count=1.
Mar 17 22:39:38 NOK-DB-2 lkscsid[12268]: INFO:lkscsid:::007090:lkscsid: device checking thread (id=-1955158272) for device '/dev/sdb' is hung for 15 seconds.
Mar 17 22:39:42 NOK-DB-2 lkscsid[12268]: INFO:lkscsid:::007092:lkscsid: device checking thread (id=-1955158272) for device '/dev/sdb' is no longer hung after 20 seconds.

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이상하게 error로 뜨다가 다시 INFO로 되고....이상함....

syslog에도 에러가 뜸...

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Mar 17 22:29:56 NOK-DB-2 iscsid: connection1:0 is operational after recovery (1 attempts)
Mar 17 22:29:57 NOK-DB-2 kernel: connection1:0: detected conn error (1020)
Mar 17 22:29:57 NOK-DB-2 iscsid: Kernel reported iSCSI connection 1:0 error (1020 - ISCSI_ERR_TCP_CONN_CLOSE: TCP connection closed) state (3)
Mar 17 22:30:02 NOK-DB-2 iscsid: connection1:0 is operational after recovery (1 attempts)
Mar 17 22:30:03 NOK-DB-2 kernel: connection1:0: detected conn error (1020)
Mar 17 22:30:03 NOK-DB-2 iscsid: Kernel reported iSCSI connection 1:0 error (1020 - ISCSI_ERR_TCP_CONN_CLOSE: TCP connection closed) state (3)
Mar 17 22:30:08 NOK-DB-2 iscsid: connection1:0 is operational after recovery (1 attempts)
Mar 17 22:30:09 NOK-DB-2 kernel: connection1:0: detected conn error (1020)
Mar 17 22:30:09 NOK-DB-2 iscsid: Kernel reported iSCSI connection 1:0 error (1020 - ISCSI_ERR_TCP_CONN_CLOSE: TCP connection closed) state (3)

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2. 해결방안

 - https://access.redhat.com/solutions/27717

Setting the following timeouts in /etc/iscsi/iscsid.conf can help :

node.conn[0].timeo.noop_out_interval = 30
node.conn[0].timeo.noop_out_timeout = 30

/etc/init.d/iscsi  restart

이와 같이 수정하니 에러 메세지가 안뜸.

더 찾아봐야 하겠지만 체크 주기가 너무 짧아서 에러로도 보고, 정상적으로도 보고...한거 같음