Printers in printers list are discarded prematurely

[angelb]

> Hello all.
>
> When running CUPS in load-balance and fail-safe operation using an
> alias for BrowsePoll, the client discard its printers list too soon
> after it has no connection with a server.
>
> client:
> BrowseInterval 3600
> BrowseTimeout 172800
> BrowsePoll stlprcups01 <- alias in DNS
> BrowsePoll stlprcups02 <- alias in DNS
>
> After about 12 minutes, the client reported not being able to get
> updates from server B.
> E [09/Mar/2007:09:48:09 +0600] [cups-polld stlprcups02:631] CUPS-Get-printers failed: Unknown
>
> Then, after about 90 minutes later from the time server B was stopped, the client started to discard all printers from server B:
>
> -rw-r--r--   1 root     system       283439 Mar  9 10:08 printcap  <- original size
> -rw-r--r--   1 root     system       173802 Mar  9 11:06 printcap  <- removal in progress
> -rw-r--r--   1 root     system       162310 Mar  9 11:08 printcap  <- all printers from B are completely gone
>
> On the client, I have BrowseTimeout set to 48-hrs(172800sec) but the
> printers from server B were discarded in a hurry; 90 minutes after
> server B was stopped.
>
> I thought this may had something to do with using alias for BrowsePoll
> but it was not the case. I've changed the BrowsePoll to use the real
> host name but I got the same effect.
>
> About 110 minutes after I stopped server B, the client started to
> discard its printers list for server B.

Just a follow-up to confirmed use of DNS alias.

DNS alias used in BrowsePoll does not work. After the server is up, the
client does not recognize the server. See the following message:

N [12/Mar/2007:11:42:00 +0600] [Job 8] Print file accepted - job ID 42.
E [12/Mar/2007:12:20:21 +0600] [cups-polld stlprcups02:631] CUPS-Get-Printers fa
iled: Unknown
E [12/Mar/2007:13:20:21 +0600] [cups-polld stlprcups02:631] CUPS-Get-Printers fa
iled: Unknown
E [12/Mar/2007:14:20:21 +0600] [cups-polld stlprcups02:631] CUPS-Get-Printers fa
iled: Unknown

The idea of using DNS alias for BrowsePoll is to simplify moving
hundreds of clients to new CUPS servers, if needed.

What's more disturbing than the DNS issue is the fact that client
discards its printers list too soon if it can't restablish its
communication with the server within several hour even if its
BrowseTimeout is set for several days.

angelb