Why squid2.2STABLE5 use whole disk space ??

Dear Sir:

    We got this problem. we still don't know why casue this problem happened
?? Could someone please give us some advise.
    our os is FreeBSD 3.3-STABLE(19991125) , squid (2.2.STABLE5-hno.19991127
)
    In Squid.conf , the following lins are our cache_dir setting:

    cache_dir /cache1 8500 16 256
   cache_dir /cache2 14000 16 256
   cache_dir /cache3 14000 16 256
   cache_dir /cache4 14000 16 256
   cache_dir /cache5 14000 16 256
   cache_dir /cache6 14000 16 256

but when i use df -k to check disk space,the result does not fit our setting
, why?

/dev/da0s1e 11272517 9954905 415811 96% /cache1
/dev/da1s1e 17370434 15920350 60450 100% /cache2
/dev/da2s1e 17370434 15899352 81448 99% /cache3
/dev/da3s1e 17370434 15906471 74329 100% /cache4
/dev/da4s1e 17370434 15920088 60712 100% /cache5
/dev/da5s1e 17370434 15848889 131911 99% /cache6

and We also see many warning messages in access.log

1999/12/07 04:03:42| WARNING: newer swaplog entry for fileno 05000867
1999/12/07 04:03:44| WARNING: newer swaplog entry for fileno 05000867
1999/12/07 04:03:44| 6684672 Entries read so far.
diskHandleWrite: FD 26: disk write error: (28) No space left on device
FATAL: Write failure -- check your disk space and cache.log
Squid Cache (Version 2.2.STABLE5-hno.19991127): Terminated abnormally.
CPU Usage: 470.007 seconds
Maximum Resident Size: 211408 KB
Page faults with physical i/o: 0
1999/12/07 04:03:59| Starting Squid Cache version 2.2.STABLE5-hno.19991127
for i386-unknown-freebsde
1999/12/07 04:02:07| WARNING: newer swaplog entry for fileno 03000674
1999/12/07 04:02:08| WARNING: newer swaplog entry for fileno 0300066A
1999/12/07 04:02:08| WARNING: newer swaplog entry for fileno 0300067D
1999/12/07 04:02:08| WARNING: newer swaplog entry for fileno 0300067E
1999/12/07 04:02:09| WARNING: newer swaplog entry for fileno 03000683
1999/12/07 04:02:10| WARNING: newer swaplog entry for fileno 03000688
Received on Mon Dec 06 1999 - 19:59:57 MST