# Parameter WRITE\_LIMIT **URL:** \ **Category:** Forum\ **Tags:** Adabas-Natural, Adabas, Adabas-Basics-on-Linux-Unix-Windows, Adabas-on-Windows-UNIX, Adabas-on-Linux\ **Created:** [July 29, 2011, 11:47am UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875 "2011-07-29T11:47:54Z")\ **Posts on this page:** 11\ **Page:** 3
**Author:** ![system](https://global.discourse-cdn.com/techcommunity/original/3X/c/d/cd19967bb605d28a72d77eb83a1cae22f3df2eb8.svg) [@system](https://techcommunity.softwareag.com/u/system)\ **Post date:** [August 23, 2011, 8:31pm UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/41 "2011-08-23T20:31:46Z")
Sorry, I wanted to say, if you don’t use the default or ALL, try the default. If you use the default, specify ALL. ---
**Author:** ![Matthias1](https://avatars.discourse-cdn.com/v4/letter/m/9fc348/32.png) [@Matthias1](https://techcommunity.softwareag.com/u/Matthias1)\ **Post date:** [August 24, 2011, 2:59pm UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/42 "2011-08-24T14:59:19Z")
> [@Wolfgang Obmann](#): > > Sorry, I wanted to say, if you don’t use the default or ALL, try the default. If you use the default, specify ALL. Thanks for the hint. It seems like we’re using default at the moment. ```auto $ adaopr db=11 di=stat %ADAOPR-I-STARTED, 24-AUG-2011 11:28:55, Version 6.1.10.10 (Solaris 64Bit) Database 11, startup at 24-AUG-2011 07:03:28 ADANUC Version 6.1.10.10, PID 10458 ADANUC Version 6.1.10.10 Database 11 Static Parameters on 24-AUG-2011 11:28:55 Resources: LAB : 33,554,432 NT : 30 LBP : 536,870,912 NU : 1,500 LWP : 67,108,864 NCL : 1,500 Logging: PLOG, BI Options: TRUNCATION, OPEN_REQUIRED, AUTO_EXPAND Userexits: 2 Cloglayout: 5 Adabas Access: ALL Unbuffered: WORK, PLOG %ADAOPR-I-TERMINATED, 24-AUG-2011 11:28:55, elapsed time: 00:00:00 ``` ---
**Author:** ![Matthias1](https://avatars.discourse-cdn.com/v4/letter/m/9fc348/32.png) [@Matthias1](https://techcommunity.softwareag.com/u/Matthias1)\ **Post date:** [August 31, 2011, 1:35pm UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/43 "2011-08-31T13:35:43Z")
We tried out UNBUFFERED=ALL for the past few days. There’s no positive or negative impact on Performance. The buffer flush takes a little longer ~ 15 sec. with WRITE\_LIMIT=5 > 30 sec. with WRITE\_LIMIT=8 … but that’s no surprise. ---
**Author:** ![Matthias1](https://avatars.discourse-cdn.com/v4/letter/m/9fc348/32.png) [@Matthias1](https://techcommunity.softwareag.com/u/Matthias1)\ **Post date:** [August 31, 2011, 8:40pm UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/44 "2011-08-31T20:40:44Z")
Today I saw a phenomenon in connection with UNBUFFERED=ALL. The number of modified bytes can be greater than the write limit… Maybe this happens when there are more modifications than the storage can write for a longer time. ```auto ADANUC Version 6.1.10.10 Database 11 Buffer Pool Statistics on 31-AUG-2011 10:23:59 Buffer Pool Size : 536,870,912 Pool Allocation RABNs present --------------- ------------- Current ( 99%) : 536,815,616 ASSO : 44,813 Highwater ( 99%) : 536,840,192 DATA : 38,239 WORK : 0 NUCTMP : 14 NUCSRT : 0 I/O Statistics Buffer Flushes -------------- -------------- Logical Reads : 1,982,497,623 Total : 908 Physical Reads : 18,208,505 To Free Space : 0 Pool Hit Rate : 99% Write Limit ( 5%): 26,843,500 Physical Writes : 8,662,129 Modified ( 16%): 87,568,384 ``` ---
**Author:** ![Matthias1](https://avatars.discourse-cdn.com/v4/letter/m/9fc348/32.png) [@Matthias1](https://techcommunity.softwareag.com/u/Matthias1)\ **Post date:** [January 10, 2012, 6:06pm UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/45 "2012-01-10T18:06:35Z")
Hello all! There are some news about our problem. We did an reorganization (i.e. reorder) of the database on Dec 30th. The old duration of buffer flush: > [@Matthias](#): > > WRITE\_LIMIT=5 → ~2 sec. > WRITE\_LIMIT=8 → ~16 sec. > WRITE\_LIMIT=27 → ~100 sec. > > … all measured during dialog time. Here are the new values: WRITE\_LIMIT=5 → \<1 sec. WRITE\_LIMIT=8 → ~3 sec. WRITE\_LIMIT=27 → ~20 sec. Seems like we should do a reorder more often… Matthias ---
**Author:** ![system](https://global.discourse-cdn.com/techcommunity/original/3X/c/d/cd19967bb605d28a72d77eb83a1cae22f3df2eb8.svg) [@system](https://techcommunity.softwareag.com/u/system)\ **Post date:** [February 7, 2012, 6:33pm UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/46 "2012-02-07T18:33:04Z")
Is there any problem with WRITE\_LIMIT=1? We have a BP with a modification rate of about 1.4%/hour. With WRITE\_LIMIT=1 (minimun value) we would have a BF every (about) 43 minutes. We have checked and backup times do not get degraded. We do not have batch processing. Is there any other issue with WRITE\_LIMIT=1? (for example, could we have BF overruns in a Windows environment?) Thanks in advance ---
**Author:** ![Matthias1](https://avatars.discourse-cdn.com/v4/letter/m/9fc348/32.png) [@Matthias1](https://techcommunity.softwareag.com/u/Matthias1)\ **Post date:** [February 8, 2012, 2:24pm UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/47 "2012-02-08T14:24:58Z")
> [@Andres Calzada](#): > > Is there any problem with WRITE\_LIMIT=1? We tried it out and we got no (additional) problems with that value. But on the other hand, it didn’t solve our problems. BTW: What’s the size of your buffer pool? > [@](#): > > We have a BP with a modification rate of about 1.4%/hour. With WRITE\_LIMIT=1 (minimun value) we would have a BF every (about) 43 minutes. I think it would be less than 43 minutes - because pool size / flash rate is not linear. With a WRITE\_LIMIT of 5 we got ~ 5 Bufferflushes per hour during dialog time. ---
**Author:** ![system](https://global.discourse-cdn.com/techcommunity/original/3X/c/d/cd19967bb605d28a72d77eb83a1cae22f3df2eb8.svg) [@system](https://techcommunity.softwareag.com/u/system)\ **Post date:** [February 8, 2012, 4:04pm UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/48 "2012-02-08T16:04:14Z")
The size of our Buffer Pool is 650.000.000. With Write\_Limit=0, the Adabas chosen value is 48%, which means no Buffer Flushes throughout the day (until backup), because “Modified” grows about 1.4% per online hour. ---
**Author:** ![Matthias1](https://avatars.discourse-cdn.com/v4/letter/m/9fc348/32.png) [@Matthias1](https://techcommunity.softwareag.com/u/Matthias1)\ **Post date:** [February 16, 2012, 1:28pm UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/49 "2012-02-16T13:28:13Z")
> [@Wolfgang Obmann](#): > > My recommendation is to increase the buffer pool. The buffer pool is only 512M, this is not much on today’s machines with several GB of memory. You should try to get a bufferpool hit rate of more than 99%. Finally we followed Wolfgang Obmann’s recommendation. We’ve increased our buffer pool to 1 GB last weekend. Our hit rate is now much better than 99%. Nethertheless it doesn’t solve our performance problems during buffer flush. ```auto ADANUC Version 6.1.10.10 Database 11 Buffer Pool Statistics on 16-FEB-2012 13:26:56 Buffer Pool Size : 1,073,741,824 Pool Allocation RABNs present --------------- ------------- Current ( 99%) : 1,073,670,144 ASSO : 55,222 Highwater ( 99%) : 1,073,707,008 DATA : 95,313 WORK : 0 NUCTMP : 52 NUCSRT : 0 I/O Statistics Buffer Flushes -------------- -------------- Logical Reads : 4,126,167,769 Total : 305 Physical Reads : 24,269,102 To Free Space : 0 Pool Hit Rate : 99% Write Limit ( 3%): 32,212,230 Physical Writes : 6,793,465 Modified ( 2%): 27,668,480 %ADAOPR-I-TERMINATED, 16-FEB-2012 13:27:00, elapsed time: 00:00:00 ``` ---
**Author:** ![Matthias1](https://avatars.discourse-cdn.com/v4/letter/m/9fc348/32.png) [@Matthias1](https://techcommunity.softwareag.com/u/Matthias1)\ **Post date:** [August 3, 2012, 10:51am UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/50 "2012-08-03T10:51:45Z")
Hello all! A brief feedback: Some weeks ago we moved the ADABAS database files + plog directory to a new harddisk device. The new one is faster - especially during I/O-peaks (like buffer flushes) it is three times faster. Interestingly we can still reproduce dialog hangs. But we have to set the WRITE\_LIMIT to a value \>= 25 then (i.e. \>= 250MB). regards Matthias ---
**Author:** ![system](https://global.discourse-cdn.com/techcommunity/original/3X/c/d/cd19967bb605d28a72d77eb83a1cae22f3df2eb8.svg) [@system](https://techcommunity.softwareag.com/u/system)\ **Post date:** [April 2, 2021, 3:00pm UTC](https://techcommunity.softwareag.com/t/parameter-write-limit/97875/51 "2021-04-02T15:00:40Z")
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