The strange behavior of some /dev/sg* files
RHEL 6.4
Why only some fixed /dev/sg* file would randomly change with shift or lose with - for some unknown reason sometimes？
Notes: but the corresponding /dev/st* files themselves do not change or lose！And such problem must be resolved via reboot！
Normal：
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# lsscsi -g
......
[1:0:7:0] tape HP Ultrium 6-SCSI J3KZ /dev/st28 /dev/sg37
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 /dev/sg41
[1:0:8:0] tape HP Ultrium 6-SCSI J3KZ /dev/st29 /dev/sg39
[1:0:9:0] tape HP Ultrium 6-SCSI J3KZ /dev/st30 /dev/sg40
[1:0:10:0] tape HP Ultrium 6-SCSI J53Z /dev/st31 /dev/sg38
[1:0:11:0] tape HP Ultrium 6-SCSI J3KZ /dev/st32 /dev/sg42
[1:0:12:0] tape HP Ultrium 6-SCSI J3LZ /dev/st33 /dev/sg43
[1:0:13:0] tape HP Ultrium 6-SCSI J5KZ /dev/st34 /dev/sg44
[1:0:14:0] tape HP Ultrium 6-SCSI J3KZ /dev/st35 /dev/sg45
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Abnormal：
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# lsscsi -g
......
[1:0:7:0] tape HP Ultrium 6-SCSI J3KZ /dev/st28 /dev/sg37
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 /dev/sg41
[1:0:8:0] tape HP Ultrium 6-SCSI J3KZ /dev/st29 /dev/sg39
[1:0:9:0] tape HP Ultrium 6-SCSI J3KZ /dev/st30 /dev/sg40
[1:0:10:0] tape HP Ultrium 6-SCSI J53Z /dev/st31 -
[1:0:11:0] tape HP Ultrium 6-SCSI J3KZ /dev/st32 /dev/sg42
[1:0:12:0] tape HP Ultrium 6-SCSI J3LZ /dev/st33 /dev/sg43
[1:0:13:0] tape HP Ultrium 6-SCSI J5KZ /dev/st34 /dev/sg44
[1:0:14:0] tape HP Ultrium 6-SCSI J3KZ /dev/st35 /dev/sg45
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# lsscsi -g|grep -i 1:0:10:0
[1:0:10:0] tape HP Ultrium 6-SCSI J53Z /dev/st31 -
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# ls -l /sys/class/scsi_host/host1/scan
--w------- 1 root root 4096 Oct 24 15:56 /sys/class/scsi_host/host1/scan
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# lsscsi -g|grep -i 1:0:10:0
[1:0:10:0] tape HP Ultrium 6-SCSI J53Z /dev/st31 -
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# echo 1 > /sys/class/scsi_device/1:0:10:0/device/delete
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# lsscsi -g|grep -i 1:0:10:0
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# lsscsi -g|grep -i 1:0:10:0
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# ls -l /dev/st31
ls: cannot access /dev/st31: No such file or directory
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# echo "- - -" > /sys/class/scsi_host/host1/scan
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# lsscsi -g|grep -E "1:0:7:1|1:0:10:0"
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 -
[1:0:10:0] tape HP Ultrium 6-SCSI J53Z /dev/st31 /dev/sg41
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# echo 1 > /sys/class/scsi_device/1:0:7:1/device/delete
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# lsscsi -g|grep 1:0:7:1
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# echo "- - -" > /sys/class/scsi_host/host1/scan
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# lsscsi -g|grep 1:0:7:1
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 /dev/sg41
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# lsscsi -g|grep -E "1:0:7:1|1:0:10:0"
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 /dev/sg41
[1:0:10:0] tape HP Ultrium 6-SCSI J53Z /dev/st31 -
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# echo 1 > /sys/class/scsi_device/1:0:7:1/device/delete
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# echo 1 > /sys/class/scsi_device/1:0:10:0/device/delete
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# lsscsi -g|grep -E "1:0:7:1|1:0:10:0"
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# echo "- - -" > /sys/class/scsi_host/host1/scan
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# lsscsi -g|grep -E "1:0:7:1|1:0:10:0"
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 /dev/sg41
[1:0:10:0] tape HP Ultrium 6-SCSI J53Z /dev/st31 -
#
#
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# echo 1 > /sys/class/scsi_device/1:0:10:0/device/delete
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# lsscsi -g|grep -E "1:0:7:1|1:0:10:0"
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 /dev/sg41
#
#
#
# echo 1 > /sys/class/scsi_device/1:0:7:1/device/delete
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# echo "- - -" > /sys/class/scsi_host/host1/scan
#
#
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# lsscsi -g|grep -E "1:0:7:1|1:0:10:0"
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 /dev/sg41
[1:0:10:0] tape HP Ultrium 6-SCSI J53Z /dev/st31 -
#
#
#
# echo 1 > /sys/class/scsi_device/1:0:10:0/device/delete
#
#
#
# lsscsi -g|grep -E "1:0:7:1|1:0:10:0"
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 /dev/sg41
#
#
#
# echo "- - -" > /sys/class/scsi_host/host1/scan
#
#
#
# lsscsi -g|grep -E "1:0:7:1|1:0:10:0"
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 -
[1:0:10:0] tape HP Ultrium 6-SCSI J53Z /dev/st31 /dev/sg41
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#
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# lsscsi -g|grep -E "1:0:7:1|1:0:10:0"
[1:0:7:1] mediumx ADIC Scalar i6000 680Q /dev/sch4 -
[1:0:10:0] tape HP Ultrium 6-SCSI J53Z /dev/st31 /dev/sg41
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