* BTRFS misdetects NBD (Network Block Devices) as SSD
@ 2012-02-20 18:51 Roman Mamedov
2012-02-20 19:03 ` Chris Mason
0 siblings, 1 reply; 2+ messages in thread
From: Roman Mamedov @ 2012-02-20 18:51 UTC (permalink / raw)
To: linux-btrfs
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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."
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: BTRFS misdetects NBD (Network Block Devices) as SSD
2012-02-20 18:51 BTRFS misdetects NBD (Network Block Devices) as SSD Roman Mamedov
@ 2012-02-20 19:03 ` Chris Mason
0 siblings, 0 replies; 2+ messages in thread
From: Chris Mason @ 2012-02-20 19:03 UTC (permalink / raw)
To: Roman Mamedov; +Cc: linux-btrfs
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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