IDS Forum

Re: waiting on write of the logical log buffer

Posted By: Fernando Nunes
Date: Thursday, 27 January 2011, at 8:06 p.m.

In Response To: Re: waiting on write of the logical log buffer (KHURRAM SHAHZAD)

Hmmm...
Madison already referenced the number of recovery threads. But there's
something here that don't match properly...
You say you're using buffered logging. But on average you just use 1.8 pages
of your logical log buffer... Depending on your system page size this would
be nearly 4K or 8K out of 128 pages (256K or 512K - LOGBUFF parameter).
Typically the logical log buffer will be flushed when a commit on an
unbuffered logging table is done....
I would verify if you have any unbuffered logging database, but before that
your HDR parameters should be checked. Are you using asynchronous or
synchronous HDR?
I don't recall exactly what will cause the flush of the logical log buffer
besides a commit for an unbuffered logging database. Would need to check.

With this situation (1.8 pages/flush) your secondary must not be overloaded
by queries. I usually see this on a customer site, when the secondary is
overloaded (big DSS queries).
You should check this possibility and try Madison's suggestion. And if you
intend to use buffered logging, than you also need to check what is causing
so frequent logical log buffers flushs...

Regards

On Thu, Jan 27, 2011 at 6:39 PM, KHURRAM SHAHZAD <kshahzad02@i2cinc.com>wrote:

> Yes We have HDR + 2 RSS using buffered loging.
> Round trip time is:
>
> ---- PING Statistics----
> 9 packets transmitted, 9 packets received, 0% packet loss
> round-trip (ms) min/avg/max/stddev = 0.397/0.510/0.923/0.16
>
> output of onstat -l:
> Physical Logging
> Buffer bufused bufsize numpages numwrits pages/io
> P-2 55 128 963312 8336 115.56
>
> phybegin physize phypos phyused %used
>
> 30:301395 350000 36924 7516 2.15
>
> Logical Logging
> Buffer bufused bufsize numrecs numpages numwrits recs/pages pages/io
> L-2 0 128 13290853 1524197 835881 8.7 1.8
>
> Subsystem numrecs Log Space used
>
> OLDRSAM 13290767 1988418260
>
> HA 86 3784
>
> address number flags uniqid begin size used %used
> 11f374f98 1 U-B---- 79243 1:7573 25000 25000 100.00
> 121065d28 2 U-B---- 79244 1:32573 25000 25000 100.00
> 121065d90 3 U-B---- 79245 1:57573 25000 25000 100.00
> 121065df8 4 U-B---- 79246 1:82573 25000 24973 99.89
> 121065e60 5 U-B---- 79247 4:53 51200 51200 100.00
> 121065ec8 6 U-B---- 79248 4:51253 51200 51200 100.00
> 121065f30 7 U-B---- 79249 4:102453 51200 3785 7.39
> 121065f98 8 U-B---- 79250 4:153653 51200 51200 100.00
> 11f4e4f50 9 U-B---- 79251 4:204853 51200 51200 100.00
> 11f4e4fb8 10 U-B---- 79252 4:256053 51200 51200 100.00
> 11f4cbf50 11 U-B---- 79253 4:307253 51200 5316 10.38
> 11f4cbfb8 12 U-B---- 79254 4:358453 51200 51200 100.00
> 1211f3028 13 U-B---- 79255 4:409653 51200 42268 82.55
> 1211f3090 14 U-B---- 79256 4:460853 51200 51200 100.00
> 1211f30f8 15 U-B---- 79257 4:512053 51200 51200 100.00
> 1211f3160 16 U-B---- 79258 4:563253 51200 455 0.89
> 1211f31c8 17 U-B---- 79259 4:614453 51200 51200 100.00
> 1211f3230 18 U-B---- 79260 4:665653 51200 48300 94.34
> 1211f3298 19 U-B---- 79261 4:716853 51200 51200 100.00
> 1211f3300 20 U-B---- 79262 4:768053 51200 51200 100.00
> 1211f3368 21 U-B---- 79263 4:819253 51200 38121 74.46
> 1211f33d0 22 U-B---- 79264 4:870453 51200 51200 100.00
> 1211f3438 23 U-B---- 79265 4:921653 51200 51200 100.00
> 1211f34a0 24 U-B---- 79266 32:53 256000 255109 99.65
> 1211f3508 25 U-B---- 79267 32:256053 256000 146088 57.07
> 1211f3570 26 U---C-L 79268 32:512053 256000 125904 49.18
> 1211f35d8 27 U-B---- 79237 32:768053 256000 40527 15.83
> 1211f3640 28 U-B---- 79238 32:1024053 256000 57629 22.51
> 1211f36a8 29 U-B---- 79239 32:1280053 256000 105294 41.13
> 1211f3710 30 U-B---- 79240 32:1536053 256000 33614 13.13
> 1211f3778 31 U-B---- 79241 32:1792053 152549 24496 16.06
> 1211f37e0 32 U-B---- 79242 32:1944602 152550 68854 45.14
> 32 active, 32 total
>
>
>
> *******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>

--
Fernando Nunes
Portugal

http://informix-technology.blogspot.com
My email works... but I don't check it frequently...

--000e0cd1e07a0fe848049addac11

Messages In This Thread

• waiting on write of the logical log buffer
  KHURRAM SHAHZAD -- Thursday, 27 January 2011, at 12:52 p.m.
  • Re: waiting on write of the logical log buffer
    Fernando Nunes -- Thursday, 27 January 2011, at 1:13 p.m.
    • Re: waiting on write of the logical log buffer
      KHURRAM SHAHZAD -- Thursday, 27 January 2011, at 1:39 p.m.
      • Re: waiting on write of the logical log buffer
        Madison Pruet -- Thursday, 27 January 2011, at 2:38 p.m.
        • Re: waiting on write of the logical log buffer
          KHURRAM SHAHZAD -- Thursday, 27 January 2011, at 3:19 p.m.
          • Re: waiting on write of the logical log buffer
            Madison Pruet -- Thursday, 27 January 2011, at 3:30 p.m.
      • Re: waiting on write of the logical log buffer
        Fernando Nunes -- Thursday, 27 January 2011, at 8:06 p.m.

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