[squid-users] Failed to select source

Hi everybody,

'Coming back with "another" question... I've got a three level proxy
architecture and on the children, I often have the messages "Failed to
select source for ..."(see cache.log below). This is really disturbing
for the users because as an answer they got the error page "Unable to
forward this request at this time. ...".
I previously made some research (I've already posted some messages) on
what could cause the parents being detected DEAD, but so far I couldn't
find any answer.
The parent isn't overloaded, all and all the network connectivity is
good (speed, duplex, port errors) and they have an average of 70 req/s
during the day (the same for the children but there are 3 times more of
them). I've checked the firewall logs, no drops or reject. I've also
tried to increase the syn backlog, play with the connect timeout (squid)
and the fin timeout (/proc), with no success.

For a child, we always have three parents, and what I find really
strange is that seen from the children (cache.log below), it's always
the three parents that are seen DEAD. I never have the case where only
one parent is seen DEAD ; it's always all the parents that are seen like
that.

Any ideas?
At last resort, I'll try to chain both the child and the parents on the
same network segment, to exclude any firewall problem.

Thx in advance.

        Pierre-Emmanuel

cache.log :
2005/08/29 09:11:05| Detected DEAD Parent: parent1/8080/3130
2005/08/29 09:11:05| Detected DEAD Parent: parent2/8080/3130
2005/08/29 09:11:05| Detected DEAD Parent: parent3/8080/3130
2005/08/29 09:11:05| Failed to select source for
'http://www.espacetoutterrain.com/acces.htm'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 0
2005/08/29 09:11:05| Failed to select source for
'http://fr.wrs.yahoo.com/;_ylt=AgTyE2YRxNOBUTyQdclUkDtjAQx.;_ylu=X3oDMTB
hNjRqazhxBHNlYwNzZWFyY2g-/SIG=11k98fh49/EXP=1125385828/*http%3A//fr.sear
ch.yahoo.com/search?p=chats&ei=UTF-8&fr=fp-tab-web-t-1&fl=0&vc=&x=wrt&me
ta=vl%3D'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 0
2005/08/29 09:11:05| Failed to select source for
'http://windowsmedia.com/CAPS/ImagesContent/49127B98-D82B-440C-BDEB-3AB8
7428423C.jpg'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 0
2005/08/29 09:11:05| Failed to select source for
'http://www.boursorama.com/infos/actualites/detail_actu_marches.phtml?&n
ews=2907003'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 0
2005/08/29 09:11:05| Failed to select source for
'http://www.lerepairedesmotards.com/'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 0
2005/08/29 09:11:05| Failed to select source for
'http://forum.magicmaman.com/forum1.php?config=votrevie.inc'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 0
2005/08/29 09:11:05| Failed to select source for 'http://fr.yahoo.com/'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 0
2005/08/29 09:11:05| Failed to select source for
'http://www.journaldunet.com/0507/050722affiliation.shtml'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 0
2005/08/29 09:11:05| Failed to select source for
'http://fr.wrs.yahoo.com/;_ylt=AgTyE2YRxNOBUTyQdclUkDtjAQx.;_ylu=X3oDMTB
hNjRqazhxBHNlYwNzZWFyY2g-/SIG=11k98fh49/EXP=1125385828/*http%3A//fr.sear
ch.yahoo.com/search?p=chats&ei=UTF-8&fr=fp-tab-web-t-1&fl=0&vc=&x=wrt&me
ta=vl%3D'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 0
2005/08/29 09:11:05| Failed to select source for
'http://ad.fr.doubleclick.net/1020561/you_mm_customer_v1_336x500_20k.swf
?clickTag=http://ad.fr.doubleclick.net/click%3Bh=v5|32e3|f|60|%2a|t%3B19
188916%3B0-0%3B0%3B11705520%3B12049-336|500%3B11554603|11572499|1%3B%3B%
7Esscs%3D%3fhttp://www.smartadserver.com/clic/countgo.asp?47934,1481,868
6766726395684572,8741384140,S,0,URL=http%3A%2F%2Fwww.ibm.com/software/in
fo/middleware/succeed/fr/index.jsp?ca=2005q3_swg_plays_fr%26me=a%26met=3
36x500_fla%26re=01net'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 1
2005/08/29 09:11:05| Failed to select source for
'http://www.peugeot.fr/ppp/PPPWEBFR/configurator/vp/1pt100/thumbnail_tri
m/tt_1pt1_pafn.jpg'
2005/08/29 09:11:05| always_direct = 0
2005/08/29 09:11:05| never_direct = 1
2005/08/29 09:11:05| timedout = 0
Received on Mon Aug 29 2005 - 10:32:31 MDT