Has anyone ever tried using this feature? I've added it to the [global] section of the ceph.conf on my POC cluster but I'm not sure how to tell if it's actually working.
TIA
TIA
bluestore_default_buffered_write = true
- Thread starter Adam Koczarski
- Start date
This has some overhead, data is first written to memory (not yet acknowledged) then flushed to disk, only then acknowledged.
So it does not allow faster write completion, rather possibly slightly slower as other cache data may need to get evicted for the new to have space. Normally only makes sense if your clients need to read the data directly after the write and that more than one time. This is not a regular pattern, as read caching is most of the time done by the clients them self, as they know better what specific data may have a bigger chance to get re-read.
We recommend in general against enabling this, and if you probably have a non-normal access pattern and should try to evaluate the impact of this change first in a non-production setup for your specific access patterns.
So it does not allow faster write completion, rather possibly slightly slower as other cache data may need to get evicted for the new to have space. Normally only makes sense if your clients need to read the data directly after the write and that more than one time. This is not a regular pattern, as read caching is most of the time done by the clients them self, as they know better what specific data may have a bigger chance to get re-read.
We recommend in general against enabling this, and if you probably have a non-normal access pattern and should try to evaluate the impact of this change first in a non-production setup for your specific access patterns.
Thank you for the reply. Doesn't sound like something I'd use.
Just for reference, is there a way to tell if it's actually running? I added the following to my ceph.conf file on a POC cluster but wasn't sure if it was truly enabled?? I didn't see any increase in RAM usage beyond what was already being consumed by the OSDs for read caching.
[OSD]
bluestore_default_buffered_write = true
Just for reference, is there a way to tell if it's actually running? I added the following to my ceph.conf file on a POC cluster but wasn't sure if it was truly enabled?? I didn't see any increase in RAM usage beyond what was already being consumed by the OSDs for read caching.
[OSD]
bluestore_default_buffered_write = true