On Wed, Apr 13, 2011 at 11:01 AM, Vick Khera <vivek at khera.org> wrote:

> On Wed, Apr 13, 2011 at 1:42 PM, Richard Yen <richyen at iparadigms.com>wrote:
>
>> Well, I noticed that when the log gets large and it's in the middle of a
>> logswitch, load on the origin node will increase and subsequent to that, all
>> subscriber nodes will lag up to 900sec.  This seems troublesome, considering
>> that nodes in my cluster typically don't lag for more than 10sec--it's only
>> during these logswitch events that they lag by so much.
>>
>
> I never noticed that, even when I had my db's on spinning media.  It was
> never correlated with log switch.  The only times I got lag was when I had a
> *lot* of update/insert activity in a very very short period.
>
> Might I suggest that the cause/effect is the other way around?  Perhaps you
> are just hitting your I/O throughput limit for your hardware.
>
> That sounds like a possibility to me, but as far as I understand it, when a
subscriber is lagging, events in sl_event (and therefore sl_log_*) are not
being processed.  Wouldn't the slave lag block a logswitch from finishing?
 Or perhaps I don't fully understand the way SYNCs are processed and
purged...

--Richard
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