The idea is to avoid separate WAL partition - it doesn't make sense for
single NVMe device - just compicates things.
And if you don't specify WAL explicitly it's co-exist with DB.
Hence I vote for the second option :)
On 6/29/2018 12:07 AM, Kai Wagner wrote:
I'm also not 100% sure but I think that the first one is the right way
to go. The second command only specifies the db partition but no
dedicated WAL partition. The first one should do the trick.
On 28.06.2018 22:58, Igor Fedotov wrote:
I think the second variant is what you need. But I'm not the guru in
ceph-deploy so there might be some nuances there...
Anyway the general idea is to have just a single NVME partition (for
both WAL and DB) per OSD.
Thanks,
Igor
On 6/27/2018 11:28 PM, Pardhiv Karri wrote:
Thank you Igor for the response.
So do I need to use this,
ceph-deploy osd create --debug --bluestore --data /dev/sdb
--block-wal /dev/nvme0n1p1 --block-db /dev/nvme0n1p2 cephdatahost1
or
ceph-deploy osd create --debug --bluestore --data /dev/sdb
--block-db /dev/nvme0n1p2 cephdatahost1
where /dev/sdb is ssd disk for osd
/dev/nvmen0n1p1 is 10G partition
/dev/nvme0n1p2 is 25G partition
Thanks,
Pardhiv K
On Wed, Jun 27, 2018 at 9:08 AM Igor Fedotov <ifedo...@suse.de
<mailto:ifedo...@suse.de>> wrote:
Hi Pardhiv,
there is no WalDB in Ceph.
It's WAL (Write Ahead Log) that is a way to ensure write safety
in RocksDB. In other words - that's just a RocksDB subsystem
which can use separate volume though.
In general For BlueStore/BlueFS one can either allocate separate
volumes for WAL and DB or have them on the same volume. The
latter is the common option.
The separated layout makes sense when you have tiny but
super-fast device (for WAL) and less effective (but still fast)
larger drive for DB. Not to mention the third one for user data....
E.g. HDD (user data) + SDD (DB) + NVME (WAL) is such a layout.
So for you case IMO it's optimal to have merged WAL+DB at NVME
and data at SSD. Hence no need for separate WAL volume.
Regards,
Igor
On 6/26/2018 10:22 PM, Pardhiv Karri wrote:
Hi,
I am playing with Ceph Luminous and getting confused
information around usage of WalDB vs RocksDB.
I have 2TB NVMe drive which I want to use for Wal/Rocks DB and
have 5 2TB SSD's for OSD.
I am planning to create 5 30GB partitions for RocksDB on NVMe
drive, do I need to create partitions of WalDB also on NVMe
drive or does RocksDB does same work as WalDB plus having
metadata on it?
So my question is do I really need to use WalDB along with
RocksDB or having RocksDB only is fine?
Thanks,
Pardhiv K
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