Re: Bluestore OSD_DATA, WAL & DB

[Maged Mokhtar <mmokhtar@xxxxxxxxxxx>]

On 2017-09-21 07:56, Lazuardi Nasution wrote:

Hi,

 

I'm still looking for the answer of these questions. Maybe someone can share their thought on these. Any comment will be helpful too.

 

Best regards,

On Sat, Sep 16, 2017 at 1:39 AM, Lazuardi Nasution <mrxlazuardin@xxxxxxxxx> wrote:

Hi,

 

1. Is it possible configure use osd_data not as small partition on OSD but a folder (ex. on root disk)? If yes, how to do that with ceph-disk and any pros/cons of doing that?

2. Is WAL & DB size calculated based on OSD size or expected throughput like on journal device of filestore? If no, what is the default value and pro/cons of adjusting that?

3. Is partition alignment matter on Bluestore, including WAL & DB if using separate device for them?

 

Best regards,

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I am also looking for recommendations on wal/db partition sizes. Some hints:

ceph-disk defaults used in case it does not find bluestore_block_wal_size or bluestore_block_db_size in config file:

wal =  512MB

db = if bluestore_block_size (data size) is in config file it uses 1/100 of it else it uses 1G.

There is also a presentation by Sage back in March, see page 16:

https://www.slideshare.net/sageweil1/bluestore-a-new-storage-backend-for-ceph-one-year-in

wal: 512 MB

db: "a few" GB 

the wal size is probably not debatable, it will be like a journal for small block sizes which are constrained by iops hence 512 MB is more than enough. Probably we will see more on the db size in the future.

Maged 

 

 

 

 

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