MaxDB instance not starting

[Former Member]

Hi folks,

I'm having a problem with a MaxDB instance not starting that I'm using for a Content Server.

In my knldiag file, in the wrk directory, I find this:

2009-09-22 10:21:04 0xAFC 19776 INFO Max virtual memory: 8388607 MB

2009-09-22 10:21:04 0xAFC 19777 INFO Total physical memory: 32762 MB

2009-09-22 10:21:04 0xAFC 19778 INFO Available physical memory: 15353 MB

...

2009-09-22 10:21:04 0xAFC ERR 18872 MEMORY Not enough memory for I/O buffer cache wanted : 2794496 kB!

So, I see plenty of physical memory (32 GB) and free memory 15 GB!) I am running into the error that not enough is available.Looking at my cache size, it is listed at:

CACHE_SIZE=1397888

and I have tried using the DBMCLI to adjust it, first downwards:

D:\sapdb\programs\pgm\dbmcli.exe on server1: SDB>param_put -permanent CACHE_SIZE 1048576

resulting in: Not enough memory for I/O buffer cache wanted : 0 kB!

??

Then I tried upwards:

D:\sapdb\programs\pgm\dbmcli.exe on server1 : SDB>param_put -permanent CACHE_SIZE 2794496

Not enough memory for I/O buffer cache wanted : 1384448 kB!

So now I am at a loss...I have tried adjusting it further upwards and downwards, to no effect.

Has anyone had similar experiences? Can you provide some help?

Thanks,

Troy Shane

[lbreddemann · Accepted solution]

Hi Troy,

are you aware that the CACHE_SIZE parameter takes the number of 8k-blocks instead of kB ?

So, your CACHE_SIZE=1397888 means 11183104 kb or 10921 MB or approx. 10 GB.

In addition to the page cache the database requires memory for the task stacks, the task structures themselves and the binary as well.

Also: are you are using the 64-Bit version of MaxDB software?

What version are you using anyhow?

regards.

Lars

[Former Member]

Lars,

Thanks very much for that...it doesn't explicitly state the Unit of measure on help.sap.com, and I falsely assumed that the UoM was in KB, since that's what the error message was reporting it in.

For future reference, to fix this problem:

1397888 kb / 8 = 174736 (8k blocks)

D:\sapdb\programs\pgm\dbmcli.exe on server1 : SDB>param_put -permanent CACHE_SIZE 174736

OK

D:\sapdb\programs\pgm\dbmcli.exe on server1 : SDB>db_start

OK

and it worked!

Many thanks,

Troy

[lbreddemann]

Hi Troy,

> Thanks very much for that...it doesn't explicitly state the Unit of measure on help.sap.com, and I falsely assumed that the UoM was in KB, since that's what the error message was reporting it in.

What documentation page were you looking at?

On e.g. [General Database Parameters|http://help.sap.com/saphelp_nw70/helpdata/en/ef/eb3d408ae01e24e10000000a1550b0/content.htm] it says:

CACHE_SIZE: Size of the I/O buffer cache (in pages)

Would be good to know when there is some documentation left without this important detail.

BTW: even if you're using MaxDB 'just' for content server, make sure to have the latest patch installed to avoid problems and possible data loss (there had been some really nasty bugs in the past causing corruptions during check data etc....)

regards,

Lars