Need help understanding backend connection errors

[Jim Hayter]

Hi,

I'm looking at implementing varnish 2.0.5 as a front end to our apache
web servers to cache static files.  I'm currently testing and having
issues with backend connections.  Since this is a test system, it is not
heavily used.  I notice that if it goes without any requests for some
time (over an hour or so), the next request received goes through the
cycle below of 'FetchError  c no backend connection' and restart until
it hits the restart limit of 6.  It also seems that if requests occur
every few minutes that this is not an issue, so I suspect a timeout of
some kind.

I've been searching and reading but have not found an explanation for
this behavior yet.  

More complete log of this can be seen at
http://www.manta.com/jah/varnish_log.txt
The command line I'm using to run varnish can be seen at
http://www.manta.com/jah/varnish_start.txt
Current vcl can be seen at http://www.manta.com/jah/varnish_vcl.txt

I'd appreciate any insight.

Thanks,
Jim

Varnish_log.txt excerpt:
    4 VCL_call     c recv
    4 VCL_return   c pass
    4 VCL_call     c pass
    4 VCL_return   c pass
   31 BackendClose b default
    5 BackendClose b default
    4 FetchError   c no backend connection
    4 VCL_call     c error
    4 VCL_return   c restart
    4 VCL_call     c recv
    4 VCL_return   c pass
    4 VCL_call     c pass
    4 VCL_return   c pass
    4 FetchError   c no backend connection
    4 VCL_call     c error
    4 VCL_return   c restart
    4 VCL_call     c recv
    4 VCL_return   c pass
    4 VCL_call     c pass
    4 VCL_return   c pass
    4 FetchError   c no backend connection
    4 VCL_call     c error
    4 VCL_return   c restart
    4 VCL_call     c recv
    4 VCL_return   c pass
    4 VCL_call     c pass
    4 VCL_return   c pass
    4 FetchError   c no backend connection
    4 VCL_call     c error
    4 VCL_return   c restart
    4 VCL_call     c recv
    4 VCL_return   c pass
    4 VCL_call     c pass
    4 VCL_return   c pass
    4 FetchError   c no backend connection
    4 VCL_call     c error
    4 VCL_return   c restart
    4 VCL_call     c recv
    4 VCL_return   c pass
    4 VCL_call     c pass
    4 VCL_return   c pass
    4 FetchError   c no backend connection
    4 VCL_call     c error
    4 VCL_return   c restart
    4 VCL_call     c recv
    4 VCL_return   c pass
    4 VCL_call     c error
    4 VCL_return   c deliver
    4 Length       c 488
    4 VCL_call     c deliver
    4 VCL_return   c deliver
    4 TxProtocol   c HTTP/1.1
    4 TxStatus     c 503
    4 TxResponse   c Service Unavailable
    4 TxHeader     c Server: Varnish
    4 TxHeader     c Retry-After: 0
    4 TxHeader     c Content-Type: text/html; charset=utf-8
    4 TxHeader     c Content-Length: 488
    4 TxHeader     c Date: Tue, 08 Dec 2009 21:37:50 GMT
    4 TxHeader     c X-Varnish: 1690688575
    4 TxHeader     c Age: 0
    4 TxHeader     c Via: 1.1 varnish
    4 TxHeader     c Connection: close
    4 TxHeader     c X-Served-By: ecnext39
    4 TxHeader     c X-Cache: MISS
    4 ReqEnd       c 1690688575 1260308270.019510984
1260308270.020113707 0.004284143 0.000570059 0.000032663
    4 SessionClose c error
    4 StatSess     c 66.104.100.163 61534 0 1 1 0 6 0 273 488