Cache-DIGEST false hits

Hi,

I have a cluster of two cache-servers configured as sibling with
--enable-cache-digests option. Both are running squid-1.2.beta23 with
all patches.

Accidently, I have found that the most of CACHE_DIGEST_HIT are false hits.
For example, yesterday daily statistics for HTTP requests from the first
cache-server is:

# Outgoing requests by destination
neighbor type request % kByte % sec kB/sec
....
second-cache 3126 2.66 8328 0.87 0 0.24
 CACHE_DIGEST_HIT 3053 2.60 7838 0.82 0 0.23
 SIBLING_HIT 73 0.06 490 0.05 0 0.50

Meanwile, calamaris report from second-cache for HTTP-requests from the first
cache says:

# Incoming TCP-requests by status
status request % kByte % sec kB/sec
--------------------------------- -------- ------ --------- ------ ---- -------
HIT 1143 36.33 2250 20.35 0 4.98
 TCP_IMS_HIT 894 28.42 249 2.25 0 11.80
 TCP_HIT 218 6.93 1918 17.35 2 4.47
 TCP_MEM_HIT 22 0.70 62 0.56 0 307.15
 TCP_NEGATIVE_HIT 5 0.16 2 0.02 0 65.76
 TCP_REFRESH_HIT 4 0.13 19 0.17 0 14.69
MISS 1976 62.81 6355 57.48 20 0.16
 TCP_MISS 1976 62.81 6355 57.48 20 0.16
ERROR 27 0.86 2452 22.17 1 136.36
 TCP_IMS_MISS 27 0.86 2452 22.17 1 136.36
--------------------------------- -------- ------ --------- ------ ---- -------
Sum 3146 11056 13 0.28

# Requested content-type
content-type request % kByte % hit-%
--------------------------------------- -------- ------ --------- ------ ------
......
application/cache-digest 30 0.95 2707 24.48 16.67
--------------------------------------- -------- ------ --------- ------ ------
Sum 3146 100.00 11056 100.00 36.33

My questions are:

1. Why the are so many false hits? Is there any way to improve
using cache digest?

2. Is it possible to control cache_digest hit and miss using Cache Manager?
(Peer Selection menu seems doesn't work)

Serge Krashakov
Received on Tue Aug 18 1998 - 04:36:52 MDT