On Thu, Feb 15, 2018 at 12:15:49PM -0500, Ellis H. Wilson III wrote: > In discussing the performance of various metadata operations over > the past few days I've had this idea in the back of my head, and > wanted to see if anybody had already thought about it before > (likely, I would guess). > > It appears based on this page: > https://btrfs.wiki.kernel.org/index.php/Btrfs_design > that data and metadata in BTRFS are fairly well isolated from one > another, particularly in the case of large files. This appears > reinforced by a recent comment from Qu ("...btrfs strictly > split metadata and data usage..."). > > Yet, while there are plenty of options to RAID0/1/10/etc across > generally homogeneous media types, there doesn't appear to be any > functionality (at least that I can find) to segment different BTRFS > internals to different types of devices. E.G., place metadata trees > and extent block groups on SSD, and data trees and extent block > groups on HDD(s). > > Is this something that has already been considered (and if so, > implemented, which would make me extremely happy)? Is it feasible > it is hasn't been approached yet? I admit my internal knowledge of > BTRFS is fleeting, though I'm trying to work on that daily at this > time, so forgive me if this is unapproachable for obvious > architectural reasons.
Well, it's been discussed, and I wrote up a theoretical framework which should cover a wide range of use-cases: https://www.spinics.net/lists/linux-btrfs/msg33916.html I never got round to implementing it, though -- I ran into issues over storing the properties/metadata needed to configure it. Hugo. -- Hugo Mills | Dullest spy film ever: The Eastbourne Ultimatum hugo@... carfax.org.uk | http://carfax.org.uk/ | PGP: E2AB1DE4 | The Thick of It
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