--On Thursday, September 10, 2020 10:40 AM +0200 Frédéric Goudal frederic.goudal@bordeaux-inp.fr wrote:

Hello,

As I understand mdb database should be in memory. Is there a way to calculate the correct amount of memory that should be allocated to a server so the database fit with no swap ? I guess the maxsize attribute should be set to a correct value too..

The MDB maxsize value should be something you never anticipate hitting. I usually default to 80GB, but you want the value to something under the size of the partition (i.e., you don't want the DB to grow larger than could be stored). The DB size can be obtained from a du -c -h data.mdb, so you want to have more than enough memory to hold that amount.

Regards, Quanah

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Quanah Gibson-Mount Product Architect Symas Corporation Packaged, certified, and supported LDAP solutions powered by OpenLDAP: http://www.symas.com

Quanah Gibson-Mount wrote:

--On Thursday, September 10, 2020 10:40 AM +0200 Frédéric Goudal frederic.goudal@bordeaux-inp.fr wrote:

...

Hello,

As I understand mdb  database should be in memory.

No. The database lives on disk.

...

Is there a way to calculate the correct amount of memory that should be allocated to a server so the database fit with no swap ?

LMDB databases never cause swapping, never use swap space.

...

I guess the maxsize attribute should be set  to a correct value too..

The MDB maxsize value should be something you never anticipate hitting.  I usually default to 80GB, but you want the value to something under the size of the partition (i.e., you don't want the DB to grow larger than could be stored).  The DB size can be obtained from a du -c -h data.mdb,

Yes.

so you want to have more than enough memory to hold that amount.

No. The amount of RAM is really irrelevant, only the disk space matters. We routinely test with databases over 50x larger than RAM...