Re: Questions of KeyValueStore (leveldb) backend

[Wido den Hollander <wido@42on.com>]

On 05/26/2014 06:55 AM, Haomai Wang wrote:
> On Mon, May 26, 2014 at 9:46 AM, Guang Yang <yguang11@outlook.com> wrote:
>> Hello Haomai,
>> We are evaluating the key-value store backend which comes along with Firefly release (thanks for implementing it in Ceph), it is very promising for a couple of our use cases, after going through the related code change, I have a couple of questions which needs your help:
>>    1. One observation is that, for object larger than 1KB, it will be striped to multiple chunks (k-v in the leveldb table), with one strip as 1KB size. Is there any particular reason we choose 1KB as the strip size (and I didn’t find a configuration to tune this value)?
>
> 1KB is not a serious value, this value can be configured in the near future.
>

So that is currently hardcoded? I can't find any reference to it in 
config_opts.h

>>
>>    2. This is properly a leveldb question, do we expect performance degradation as the leveldb instance keeps increasing (e.g. several TB)?
>
> Ceph OSD is expected to own a physical disk, normally is several
> TB(1-4TB). LevelDB can take it easy. Especially we use it to store
> large value(compared to normal application usage).
>

With a large value you mean something like 4MB? The regular strip-size 
for RBD, CephFS and such?

>>
>> Thanks,
>> Guang
>
>
>


-- 
Wido den Hollander
42on B.V.

Phone: +31 (0)20 700 9902
Skype: contact42on
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html