Re: Replication vs Data Guard
- From: Denis <denis.sun@xxxxxxxxx>
- To: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>, "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 11 Jan 2012 16:17:43 -0800 (PST)
Brandon,
Thanks for sharing your data and all others replying me in the list or
privately. I am wondering for how your "apply lag" varies depending on redo
generate rate if any. Will a burst of redo change the "apply lag"? Also I am
not sure how Oracle calculate this lag. For comparison, I share my latency
data. In my replication set up we at soure insert a row into a table every
min and using a trigger at target db to capture target insert time. Source is
at CA and target is at NY, ie from west to east in US. , then compare source
insert time and target insert time, in such way we get the latency in second. I
looked half hour awr for 14:00-14;30, redo is 1,678,257.19 per seond. The
latency is as follows:
ID SRC_INS_TIME TGT_INS_TIME LATENCY
---------- ------------------- ------------------- ----------
3710400 2012-01-11 14:00:01 2012-01-11 14:00:06 5
3710401 2012-01-11 14:01:01 2012-01-11 14:01:03 2
3710402 2012-01-11 14:02:01 2012-01-11 14:02:03 2
3710403 2012-01-11 14:03:01 2012-01-11 14:03:06 5
3710404 2012-01-11 14:04:00 2012-01-11 14:04:03 3
3710405 2012-01-11 14:05:00 2012-01-11 14:05:06 6
3710406 2012-01-11 14:06:00 2012-01-11 14:06:06 6
3710407 2012-01-11 14:07:00 2012-01-11 14:07:04 4
3710408 2012-01-11 14:08:00 2012-01-11 14:08:03 3
3710409 2012-01-11 14:09:01 2012-01-11 14:09:06 5
3710410 2012-01-11 14:10:01 2012-01-11 14:10:05 4
3710411 2012-01-11 14:11:00 2012-01-11 14:11:04 4
3710412 2012-01-11 14:12:01 2012-01-11 14:12:11 10
3710413 2012-01-11 14:13:01 2012-01-11 14:13:06 5
3710414 2012-01-11 14:14:00 2012-01-11 14:14:03 3
3710415 2012-01-11 14:15:01 2012-01-11 14:15:03 2
3710416 2012-01-11 14:16:00 2012-01-11 14:16:03 3
3710417 2012-01-11 14:17:00 2012-01-11 14:17:05 5
3710418 2012-01-11 14:18:00 2012-01-11 14:18:10 10
3710419 2012-01-11 14:19:00 2012-01-11 14:19:05 5
3710420 2012-01-11 14:20:00 2012-01-11 14:20:04 4
3710421 2012-01-11 14:21:00 2012-01-11 14:21:04 4
3710422 2012-01-11 14:22:01 2012-01-11 14:22:04 3
3710423 2012-01-11 14:23:01 2012-01-11 14:23:06 5
3710424 2012-01-11 14:24:00 2012-01-11 14:24:05 5
3710425 2012-01-11 14:25:00 2012-01-11 14:25:03 3
3710426 2012-01-11 14:26:00 2012-01-11 14:26:04 4
3710427 2012-01-11 14:27:00 2012-01-11 14:27:05 5
3710428 2012-01-11 14:28:01 2012-01-11 14:28:03 2
3710429 2012-01-11 14:29:01 2012-01-11 14:29:05 4
Again I understand different purpose of replication and dataguard, just curious
about in the best case scenario, can replication technology beat dataguard in
term of latency since amount of data transport across network seem different
between them.
________________________________
From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
To: "denis.sun@xxxxxxxxx" <denis.sun@xxxxxxxxx>; "oracle-l@xxxxxxxxxxxxx"
<oracle-l@xxxxxxxxxxxxx>
Sent: Wednesday, January 11, 2012 11:34 AM
Subject: RE: Replication vs Data Guard
I'm getting about 4 seconds latency on my standby using Data Guard with
Real-Time Apply, but this standby can't be used for anything unless I stop the
redo apply and open it read-only (or do a switchover or failover). So, if you
need to use your secondary/standby/destination database for something other
than DR or intermittent read-only access then you need to consider other
replication options, or Active Data Guard.
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