Hi Mark,
ha ha ha, this is a brilliant misunderstanding :) I was under the impression that since mimic all ceph developers were instructed never to mention the ceph.conf file again and only ever talk about the ceph config data base instead. The only allowed options in a config file are the monitor addresses (well, a few more but the idea is a minimal config file). And that's how my config file looks like.
OK, I think we do mean the same thing. There are currently 2 sets of compression options, the bluestore and the pool options. All have 3 values and depending on which combination of values is active for a PG, a certain result becomes the final. I believe the actual compression option applied to data was defined by a matrix like that:
bluestore opt | pool option
| n | p | a
n | n | n | n
p | n | p | p
a | n | p | a
I think the bluestore option is redundant, I set these on OSD level:
bluestore_compression_min_blob_size_hdd 262144
bluestore_compression_mode aggressive
I honestly don't see any use of the bluestore options and neither do I see any use case for mode=passive. Simplifying this matrix to a simple per-pool compression on/off -flag with an option to choose the algorithm per pool as well seems a good idea and might even be a low-hanging fruit.
I need to collect some performance data from our OSDs for answering your questions about higher-level compression possibilities. I was a bit busy today with other stuff. I should have something for you next week.
Best regards and a nice weekend,
=================
Frank Schilder
AIT Risø Campus
Bygning 109, rum S14
________________________________________
From: Mark Nelson <mnelson@xxxxxxxxxx>
Sent: 11 August 2022 16:51:03
To: Frank Schilder; ceph-users@xxxxxxx
Subject: Re: Request for Info: bluestore_compression_mode?
On 8/11/22 03:20, Frank Schilder wrote:
> Hi Mark,
>
> I'm preparing a response with some data from our production system and will also open a new thread on the tail merging topic. Both topics are quite large in themselves. Just a quick question for understanding:
>
>> I was in fact referring to the yaml config and pool options ...
> I don't know of a yaml file in ceph. Do you mean the ceph-adm spec file?
oh! We switched the conf parsing over to using yaml templates:
https://github.com/ceph/ceph/blob/main/src/common/options/global.yaml.in#L4428-L4452
sorry for being unclear here, I just meant the
bluestore_compression_mode option you specify in the ceph.conf file.
Mark
>
> Best regards,
> =================
> Frank Schilder
> AIT Risø Campus
> Bygning 109, rum S14
>
> ________________________________________
> From: Mark Nelson <mnelson@xxxxxxxxxx>
> Sent: 10 August 2022 22:28
> To: Frank Schilder; ceph-users@xxxxxxx
> Subject: Re: Request for Info: bluestore_compression_mode?
>
> On 8/10/22 10:08, Frank Schilder wrote:
>> Hi Mark.
>>
>>> I actually had no idea that you needed both the yaml option
>>> and the pool option configured
> [...]
>
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