From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wido den Hollander Subject: Re: Questions of KeyValueStore (leveldb) backend Date: Mon, 26 May 2014 11:23:00 +0200 Message-ID: <538307F4.8090101@42on.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from websrv.42on.com ([31.25.102.167]:51254 "EHLO websrv.42on.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751515AbaEZJXD (ORCPT ); Mon, 26 May 2014 05:23:03 -0400 In-Reply-To: Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Haomai Wang , Guang Yang Cc: Ceph-devel On 05/26/2014 06:55 AM, Haomai Wang wrote: > On Mon, May 26, 2014 at 9:46 AM, Guang Yang wr= ote: >> 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 promi= sing for a couple of our use cases, after going through the related cod= e change, I have a couple of questions which needs your help: >> 1. One observation is that, for object larger than 1KB, it will b= e 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=E2=80=99t 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=20 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=20 for RBD, CephFS and such? >> >> Thanks, >> Guang > > > --=20 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" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html