Chasing 503 Guru's

[Simon Males]

On Fri, Dec 3, 2010 at 12:04 AM, Per Buer <perbu at varnish-software.com> wrote:
> On Thu, Dec 2, 2010 at 1:28 PM, Simon Males <sime at sime.net.au> wrote:
>> Just wanted to share my understanding of tracking down 503 / Guru
>> meditation errors.
>>
>> Steps:
>> 1. Source the XID
>> 2. Start varnishlog with -d
>> 3. Search the output for the above mentioned XID
>> 4. Hopefully the log entry will provide a clue
>>
>> Though how long do the shared memory logs exist?
>
> Depends on how much traffic you have. On a busy site it should be a
> minute or so. Try logging to disk and you notice how long 80MB (the
> default) will last. It will give you an indication on how long the
> shmlog lasts. However, the shmlog has some fixed length records so it
> wastes a bit of space compared to the output to disk.

So `varnishlog -w /tmp/varnishd.log` is self managing/rotating?

I performed the above with -d and it maintained at 58M. Without -d
it's growing slowly then expected. 7M after 20 minutes of traffic.

Where is logging to disk size specified?

>> Or is it common practice to write varnishlog to disk in production environments?
>
> No. On Linux the vm get's slightly dazzled by all the IO and will
> behave strangely. You can instruct varnishlog to only log 503's. That
> might be ideal for you.

I'm not sure how to do this. The closest I get is:

varnishlog -o -i TxStatus -I 503

Though that doesn't return the whole entry.

-- 
Simon Males