The Linux kernel keeps certain messages in a ring buffer. To view these messages, enter the command dmesg:
$ dmesg [...] sdc : READ CAPACITY failed. sdc : status = 1, message = 00, host = 0, driver = 08 Info fld=0xa00 (nonstd), Current sd00:00: sense key Not Ready sdc : block size assumed to be 512 bytes, disk size 1GB. sdc: test WP failed, assume Write Enabled sdc: I/O error: dev 08:20, sector 0 I/O error: dev 08:20, sector 0 I/O error: dev 08:20, sector 2097144 I/O error: dev 08:20, sector 2097144 I/O error: dev 08:20, sector 0 I/O error: dev 08:20, sector 0 unable to read partition table I/O error: dev 08:20, sector 0 nfs: server totan not responding, still trying nfs: server totan OK
The last line indicates that there is a temporary problem in the NFS server totan. The lines up to that point are triggered by the insertion of a USB flash drive.
Older events are logged in the files /var/log/messages and /var/log/warn.