Re: ceph-disk vs keyvaluestore

[Mark Kirkwood <mark.kirkwood@catalyst.net.nz>]

On 30/09/14 17:05, Sage Weil wrote:
> On Tue, 30 Sep 2014, Haomai Wang wrote:
>> Hi sage,
>>
>> What do you think use existing ObjectStore::peek_journal_fsid
>> interface to detect whether journal needed.
>>
>> KeyValueStore and MemStore could set passing argument "fsid" to zero
>> to indicate no journal.
>
> I'm not sure it's a good fit... it's called on an existing store and tells
> you something about it.  I would probably expect a zeroed fsid to mean
> that the specified journal is empty or does not exist, not that it doesn't
> need to exist.
>
> What we need, on the other hand, is something that just tells us whether
> we should create a journal...
>
>

And perhaps the "type" (probably not the right word) of journal:

- filestore: device or filesystem
- rocksdb: filesystem (wal directory)
- leveldb: none (I think)

FWIW, it looks like the log files for leveldb *could* benefit from being 
placed somewhere else (e.g on faster storage). Is it worthwhile 
suggesting to the leveldb devs?

Cheers

Mark