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From: Paul Jones <paul@pauljones.id.au>
To: Tomasz Chmielewski <tch@virtall.com>,
	Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: RE: dedicated metadata drives?
Date: Wed, 9 Jan 2019 02:39:10 +0000	[thread overview]
Message-ID: <SYCPR01MB5086891E71B5CDBDED74CBD19E8B0@SYCPR01MB5086.ausprd01.prod.outlook.com> (raw)
In-Reply-To: <fcdfebdcb0e8d5fd291d08f844274212@virtall.com>

> -----Original Message-----
> From: linux-btrfs-owner@vger.kernel.org <linux-btrfs-
> owner@vger.kernel.org> On Behalf Of Tomasz Chmielewski
> Sent: Saturday, 5 January 2019 12:25 AM
> To: Btrfs BTRFS <linux-btrfs@vger.kernel.org>
> Subject: dedicated metadata drives?
> 
> According to btrfs wiki, some patches have been submitted to support
> metadata on different devices than data (i.e. metadata on SSD, data on
> HDD):
> 
> 
> https://btrfs.wiki.kernel.org/index.php/Project_ideas#Dedicated_metadata
> _drives
> 
>     Dedicated metadata drives
> 
>     Not claimed — submitted — Not in kernel yet
> 
>     We're able to split data and metadata IO very easily. Metadata tends to be
> dominated by seeks and for many applications it makes sense to put the
> metadata onto faster SSDs.
> 
> 
> 
> 
> This article (almost 2.5 years old) claims one company is already using either
> these patches or something similar:
> 
> https://lwn.net/Articles/698090/
> 
>     August 24, 2016
> 
>     To combat that, he has a set of patches to automatically put the Btrfs
> metadata on SSDs. The block layer provides information on whether the
> storage is rotational; for now, his patch assumes that if
>     it is not rotational then it is fast. The patch has made a huge difference in
> the latencies and requires less flash storage (e.g. 450GB for 40TB filesystem)
> for Facebook's file workload that
>     consists of a wide variety of file sizes.
> 
> 
> 
> Do these patches exist anywhere? I couldn't find them in the list archive.

I managed to find this suggestion about how it could be done:
https://patchwork.kernel.org/patch/9556973/

I would love to use this feature as well. My current setup uses btrfs on lvm with caching enabled, but I would prefer a simpler setup.

Paul.

  reply	other threads:[~2019-01-09  2:39 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-04 13:25 dedicated metadata drives? Tomasz Chmielewski
2019-01-09  2:39 ` Paul Jones [this message]
2019-01-09 13:33   ` Eli V

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