From: Adam Borowski <kilobyte@angband.pl>
To: kreijack@inwind.it
Cc: Graham Cobb <g.btrfs@cobb.uk.net>, linux-btrfs@vger.kernel.org
Subject: Re: [RFC][PATCH V3] btrfs: ssd_metadata: storing metadata on SSD
Date: Sun, 5 Apr 2020 23:58:03 +0200 [thread overview]
Message-ID: <20200405215803.GA21928@angband.pl> (raw)
In-Reply-To: <4f10882a-fa89-25e0-901c-aff8010d46cd@libero.it>
On Sun, Apr 05, 2020 at 08:47:15PM +0200, Goffredo Baroncelli wrote:
> Currently BTRFS allocates the chunk on the basis of the free space.
>
> For my tests I have a smaller ssd (20GB) and a bigger hdd (230GB).
> This means that the latter has higher priority for the allocation,
> until the free space became equal.
>
> The rationale behind my patch is the following:
> - is quite simple (even tough in 3 iteration I put two errors :-) )
> - BTRFS has already two kind of information to store: data and metadata.
> The former is (a lot ) bigger, than the latter. Having two kind of storage,
> one faster (and expensive) than the other, it is natural to put the metadata
> in the faster one, and the data in the slower one.
But why do you assume that SSD means fast? Even with traditional disks
only, you can have a SATA-connected array for data and NVMe for metadata,
legacy NVMe for data and NVMe Optane for metadata -- but the real fun starts
if you put metadata on Optane pmem.
There are many storage tiers, and your patch hard-codes the lowest one as
the only determinator.
Meow!
--
⢀⣴⠾⠻⢶⣦⠀
⣾⠁⢠⠒⠀⣿⡁ in the beginning was the boot and root floppies and they were good.
⢿⡄⠘⠷⠚⠋⠀ -- <willmore> on #linux-sunxi
⠈⠳⣄⠀⠀⠀⠀
next prev parent reply other threads:[~2020-04-05 21:58 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-05 8:26 [RFC][PATCH V3] btrfs: ssd_metadata: storing metadata on SSD Goffredo Baroncelli
2020-04-05 8:26 ` [PATCH] btrfs: add ssd_metadata mode Goffredo Baroncelli
2020-04-14 5:24 ` Paul Jones
2020-10-23 7:23 ` Wang Yugui
2020-10-23 10:11 ` Adam Borowski
2020-10-23 11:25 ` Qu Wenruo
2020-10-23 12:37 ` Wang Yugui
2020-10-23 12:45 ` Qu Wenruo
2020-10-23 13:10 ` Steven Davies
2020-10-23 13:49 ` Wang Yugui
2020-10-23 18:03 ` Goffredo Baroncelli
2020-10-24 3:26 ` Paul Jones
2020-04-05 10:57 ` [RFC][PATCH V3] btrfs: ssd_metadata: storing metadata on SSD Graham Cobb
2020-04-05 18:47 ` Goffredo Baroncelli
2020-04-05 21:58 ` Adam Borowski [this message]
2020-04-06 2:24 ` Zygo Blaxell
2020-04-06 16:43 ` Goffredo Baroncelli
2020-04-06 17:21 ` Zygo Blaxell
2020-04-06 17:33 ` Goffredo Baroncelli
2020-04-06 17:40 ` Zygo Blaxell
2020-05-29 16:06 ` Hans van Kranenburg
2020-05-29 16:40 ` Goffredo Baroncelli
2020-05-29 18:37 ` Hans van Kranenburg
2020-05-30 4:59 ` Qu Wenruo
2020-05-30 6:48 ` Goffredo Baroncelli
2020-05-30 8:57 ` Paul Jones
2020-04-27 15:06 Torstein Eide
2020-04-28 19:31 ` Goffredo Baroncelli
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