cache disk failure handling?

[Chris Woodfield <rekoil@xxxxxxxxxxxxx>]

Hi,

Reading the squid FAQ, it's obvious to me that putting cache_dirs on a  
RAID (particularly RAID5) has serious performance penalties and is  
highly discouraged. However, what's not as clear is how squid deals  
with single-disk failures and whether or not it handles failures  
gracefully enough to obviate the need for RAID.

If I have a squid running multiple cache_dirs on single disks, and one  
disk suffers a failure, how does squid respond? Will it simply stop  
using that cache_dir and soldier on, or can this cause an application  
crash?

Also, when starting up squid, what is the effect of an unavailable  
cache_dir? I'm thinking of a situation where squid is restarted before  
a bad disk can be replaced.

If squid does have problems here, could using pairs of RAID1  
partitions be an acceptable compromise, with the cost of reduced total  
storage?

Thanks,

-Chris