On Wed, Apr 13, 2011 at 11:01 AM, Vick Khera <[email protected]> wrote:
> On Wed, Apr 13, 2011 at 1:42 PM, Richard Yen <[email protected]>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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