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SDS secondary using up nearly all memory

Posted: Tue Aug 25, 2020 11:15 am
by darrella
We are using SDS for a production system, but the secondary getting ~99% memory utilisation, where more than half is with swap/page.

I've had a look through the SDS INI settings, but can't see anything obvious.

Are there any other config settings to manage this please ?

Re: SDS secondary using up nearly all memory

Posted: Tue Aug 25, 2020 12:33 pm
by allistar
Hi Darrell,
The [PersistentDb] DiskCacheMaxSegments tells the database server how much memory the database engine can use for disk cache. This is in units of 64Mb, so a setting of "40" allows it to use about 2.5Gb. Check this setting and make sure it's not too high.

Regards,
Allistar.

Re: SDS secondary using up nearly all memory

Posted: Tue Aug 25, 2020 12:54 pm
by darrella
Thanks Allistar, we'll give that a try.

DarrellD

Re: SDS secondary using up nearly all memory

Posted: Tue Aug 25, 2020 12:55 pm
by BeeJay
Hi Darrell,

<snip>...

Never mind, it looks like Allistar beat me to the punch regarding DiskCacheMaxSegments setting. You should also check the DiskCacheBlocksPerSegment setting in the [PersistentDb] section in case the default 64M size has been increased.

Cheers,
BeeJay.

Re: SDS secondary using up nearly all memory

Posted: Thu Aug 27, 2020 10:22 am
by JohnP
Note that the default for [PersistentDb] DiskCacheMaxSegments is half of physical memory, so if you haven't specified it, the db will try to take up that much. If you have multiple databases, three for instance, they all try to take half of physical memory. In other words, the default assumes only one database per machine.