From: Chris Mason <chris.mason@oracle.com>
To: Roman Mamedov <rm@romanrm.ru>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: BTRFS misdetects NBD (Network Block Devices) as SSD
Date: Mon, 20 Feb 2012 14:03:56 -0500 [thread overview]
Message-ID: <20120220190356.GR4078@shiny> (raw)
In-Reply-To: <20120221005157.3b9f8db9@natsu>
On Tue, Feb 21, 2012 at 12:51:57AM +0600, Roman Mamedov wrote:
> Hello,
>
> I have noticed I have the following in my dmesg:
>
> [319769.043163] nbd: registered device at major 43
> [319769.104176] nbd11: unknown partition table
> [319769.130273] device fsid c2598ff2-1e3e-4edf-ab19-1f7ab41b0160 devid 1 transid 125743 /dev/nbd11
> [319769.130522] btrfs: force lzo compression
> [319769.130528] btrfs: disk space caching is enabled
> [319802.926547] Btrfs detected SSD devices, enabling SSD mode
>
> The /dev/nbd11 device itself is not an SSD, it's an LVM volume situated on a
> RAID5 array of regular hard drives, exported via NBD from another computer.
>
> https://en.wikipedia.org/wiki/Network_block_device
Btrfs pulls this information from the rotational flag on the block
device. A few different devices set this incorrectly, but it's up to
the admin to flag it in /sys/block/xxx if they want something other than
the default.
-chris
prev parent reply other threads:[~2012-02-20 19:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-20 18:51 BTRFS misdetects NBD (Network Block Devices) as SSD Roman Mamedov
2012-02-20 19:03 ` Chris Mason [this message]
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