Why am I experiencing I/O error in my /var/log/messages file, and what does it mean?

You may see errors similar to the ones below in your /var/log/messages:
kernel: end_request: I/O error, dev sdb, sector 970590828
kernel: scsi0 (1:0): rejecting I/O to offline device
kernel: Buffer I/O error on device sdb8, logical block 2014311
kernel: lost page write due to I/O error on sdb8
kernel: I/O error in filesystem ("sdb7") meta-data dev sdb7 block 0x1e980dcc ("xlog_iodone") error 5 buf count 2048
kernel: Filesystem "sdb7": Log I/O Error Detected. Shutting down filesystem: sdb7

- The firmware was not updated on Hard drives and/or Perc raid controller - If firmware was applied, It is possible the hardware has failed  - Bad SCSI cable - File system corrupted

- Corruption on the disk has caused data loss causing SIM services to fail to start

If you are experiencing I/O errors in your messages log, please prepare your SSIM log files and call into support immediately.

Follow instructions on this KB to collect SSIM appliance log files,

(How to collect SSIM log files from the SSIM (WebGui) configuration console.)
http://www.symantec.com/docs/TECH90208

(How to gather logs from SSIM 4.6.x and 4.7.x if you cannot access the WebUI)
http://www.symantec.com/docs/TECH145655