syslog filling up root partition

[CJ]

This morning I was greeted by dialog box telling me about low disk space,
/ was full and I found /var was at 100%, with 20G syslog file.
I tried to load the file to have a look but got impatient - it was 
taking forever.

I found a post at the forums stating:
"You can truncate (and start over) those files on a running system by 
(as root):

cp /dev/null /var/log/xxxx.log"

I ran the command and /var was then back to 15% use.
It's already grown 3% since I began writing this and rsyslogd is using 
28% of the cpu.
I've just run cat /var/log/syslog and am watching it fill up again with 
5 or 6 entries every second:
"...acacia kernel: [xxxxxx.xxxxxx] metapage_read_end_io: I/O error

The hard disk is new (Hitachi 2TB) and the Maverick installation is 
barely over a week old. The disk utility reports the disk is healthy.

Searching on the error  hasn't turned up anything relevant yet.
Would anyone have an idea how to troubleshoot this error further?

Thanks