Dear Friends
I found prolem in RHEL-3 UPDATE-8 Server and i give you whole logs of server .There in no stores connect with server or other scsi device .
only Raid 5 Configure with 4 SAS(Serial Atteched SCSI) HDD.nothing Hotspare .
jun 24 10:05:29 xyz-abc1 kernel: SCSI device sdb: 2097151 512-byte hdwr sectors (1074 MB)
sdb: I/O error: dev 08:10, sector 0

I/O error: dev 08:10, sector 0
i found mounted device and umount this volume then error stop but after rebooting server, prolem repeat.so i take a chance and format the server .at this time problem resolved. but i have use a 2GB pendrive Then it shows same error and pendrive take a drive latter Hdc1.
I don't understand what is the reson behind it.

Before Thanks
Lalit Malviya
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LOGS OF SERVER

Jun 24 10:05:28 xyz-sdb1 /etc/hotplug/usb.agent: Setup keybdev for USB product 3f0/24/300

Jun 24 10:05:28 xyz-sdb1 devlabel: devlabel's temporary ignore list /etc/sysconfig/devlabel.d/ignore_list has been emptied due to a change in device configuration.

Jun 24 10:05:29 xyz-sdb1 kernel: SCSI device sdb: 2097151 512-byte hdwr sectors (1074 MB)

Jun 24 10:05:29 xyz-sdb1 kernel: sdb: I/O error: dev 08:10, sector 0

Jun 24 10:05:29 xyz-sdb1 kernel: I/O error: dev 08:10, sector 0

Jun 24 10:05:29 xyz-sdb1 kernel: unable to read partition table

Jun 24 10:05:29 xyz-sdb1 devlabel: The device /dev/sdb is being put in devlabel's temporary ignore list /etc/sysconfig/devlabel.d/ignore_list to avoid errors.

Jun 24 10:05:30 xyz-sdb1 /etc/hotplug/usb.agent: Setup hid for USB product 46d/c001/2900

Jun 24 10:05:30 xyz-sdb1 /etc/hotplug/usb.agent: Setup mousedev for USB product 46d/c001/2900