On Fri, 14 Dec 2012 08:47:59 +1300, Robert martin <rob@...> wrote:

> Hi
>
> One of our clients has a machine where intermittently the system crawls
> to almost stop. Launching programs (like paint) takes about 2 minutes
> to open. The CPU usage is low (1-3 %) but HDD usage shows at between 97

> - 100%. This situation can last 30 mins to 2 hrs before returning to
> normal.
>
> I raise the issue here because we have traced the cause to Firebird.
> When the machine is on a go slow, stopping the Firebird service fixes
> the problem. Sometimes starting the service again and connecting breaks

> the system again, sometimes it doesn't. I had though the issue may have

> been garbage collection but we have moved from FB 2.0 super server to FB

> 2.5.2 super classic and are still getting the problem. I'm pretty sure
> garbage collection is supposed to be a low priority activity, right?
>
> The system often enters 'slow more' straight after being rebooted.
>
> The weird thing is that while the system is slow and the HDD shows at
> around 100% use in resource monitor, the actually data throughput is
> about 1 ro 5MB a sec. This is can be much higher when the system runs
> normally. This made me think the HDD might be faulty but all
> indications are that its not (according to a hardware technician) and of

> course the problem fixes itself when stopping Firebird.
>
> System is
> i7 quad core (8 cores in Windows)
> 10 GB Ram
> Windows 7 64bit
> 16GB free hdd space
>
> Firebird 2.5.2 64bit
> DB size is 2.7 GB
>
>
> Any suggestions would be greatly appreciated. I know that there are
> monitoring functions built into FB 2.5.2, should I try those? If so any

> suggestions as to what to do / look for, I have not used the monitoring
> tables before.

The issue might be related to the Windows filesystem cache. Especially on
64 bit systems this can cause all available memory to be consumed by the
cache, causing a lot of swapping and therefor slow response of the system.
The firebird.conf has an option to limit the filesystem cache use. See
http://www.firebirdfaq.org/faq333/ and the 2.5 releasenotes:
http://www.firebirdsql.org/file/documentation/release_notes/html/rlsnotes251.html#rnfb25-fbconf-fscache

Mark