From mboxrd@z Thu Jan 1 00:00:00 1970 From: dexen deVries Subject: Re: Split some metadata onto separate device? Date: Fri, 3 Jun 2011 19:42:28 +0200 Message-ID: <201106031942.29133.dexen.devries@gmail.com> References: <201106031229.38758.dexen.devries@gmail.com> <20110604.022621.01482278.ryusuke@osrg.net> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:from:to:subject:date:user-agent:references :in-reply-to:x-face:mime-version:content-type :content-transfer-encoding:message-id; bh=e6LxvLhS7i4T3TadpGIpcyaSvl4iwd8JhlUt4sxpx2k=; b=ewYUNgjEs/WJzVjBjK27W/piMnimjPQY7/EIbhHg/JynRPCa1wAZ/YCJFPakdVtb/s bpYefB5epUxnv20HKrIJRv7DvPzHKRgd1yEr0CAdwO1F+wo4IC0VtTzNT8Nv2fZhBSzb UFajhYNGPS9yc0RM1Rt/TlxQKr3l++W7fdf/g= In-Reply-To: <20110604.022621.01482278.ryusuke-sG5X7nlA6pw@public.gmane.org> Sender: linux-nilfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: Text/Plain; charset="us-ascii" To: linux-nilfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Hi Ryusuke, On Friday 03 June 2011 19:26:21 you wrote: > (...) > NILFS2 is a log-structured filesystem and that means the filesystem > itself is a big journal. My understanding is using separate journal > device has no merit of performance. > > On the other hand, We may be able to speed up the filesystem by > putting DAT (disk address translation) metadata to a separate device. > I mean putting a full copy of the DAT metadata on the sperate device > instead of journal of it. *nods* sounds interesting. Of course changing on-disk format would hurt ;-) > But, I think we have other approaches to think about before that with > regard to performance improvement. For example, applying "extent" to > DAT seems much more effective. Currently every block of file gets own entry in DAT, right? By the way, it seems to me that the in-kernel GC does not attempt to de- fragment files. Is that the case? If so, would probably mean extents would not help very much for fragmented files. Also, on magnetic media, a lot of seeking happens in case of fragmented files. Regards, -- dexen deVries ``One can't proceed from the informal to the formal by formal means.'' -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html