[Spread-users] problem with spread/mod_log_spread/spreadlogd
Jeroen
quagga at muntinternet.nl
Tue Sep 6 17:30:26 EDT 2005
Theo Schlossnagle wrote:
> John Schultz wrote:
>
>> Well -11 is CONNECTION_CLOSED, which just means the connection
>> between the client and daemon has been shut down. The most common
>> reason for this is a flow control problem where msgs are being
>> injected into the system faster than readers can read them out. At
>> some point Spread will kick the connection so that it doesn't run out
>> of memory and kill the daemon, thus losing all of its connections.
>>
>> I'm not familiar with mod_log_spread and I don't know if it performs
>> any kind of flow control. If it doesn't and you are logging too fast
>> this could cause your clients to be repeatedly disconnected (assuming
>> they reconnect).
>
>
> mod_log_spread does no flow control what-so-ever. spreadlogd will
> read message from Spread as fast as it can write to disk. So, the
> typical reason for this sort of behaviour is that you try to journal
> the logs from your entire cluster on an IDE system or some other slow
> storage facility.
>
> The lack of flow control was a design decision in mod_log_spread. In
> otder to have time-ordered, real-time logs, you either must have no
> flow control or you must allow the publishers to block. In m_l_s, it
> was decided that under no circumstances should publishers block (as
> that would mean a slowdown in serving web pages). If that approach
> doesn't "jive" with your idea of logging in a web cluster, then m_l_s
> isn't for you.
>
> (The *you* above, is of course not John, but whomever is running m_l_s)
>
Thank you for your awnser!
this is exactly what my thought were, but the problem is that the system
that is writing the logs to disk is a scsi-320 system with hardware
raid-1 :)
it's just writing about 100mb of logs per hour, that doesn't look that
much to me.
Load is low on that server since it is a dedicated logserver, but I/O
might be a problem (since that isn't always shown in pure load).
I'll hookup a raid-10 system with 15k rpm disks tomorrow and test further.
Another problem believing this conclusion is that we have another
cluster that is performing great loging to a sata-raid array, writing
almost 2 gigs of logs every hour, but that is another setup.
Kind regards and please give your comments since this isn't solved yet,
Jer
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