Btrfs devel - Feb 2012 - BTRFS misdetects NBD (Network Block Devices) as SSD

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

-- 
With respect,
Roman

~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Stallman had a printer,
with code he could not see.
So he began to tinker,
and set the software free."

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

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