* Is there a "nossd" option ?
@ 2015-06-21 17:13 Swâmi Petaramesh
2015-06-21 17:31 ` Roman Mamedov
0 siblings, 1 reply; 5+ messages in thread
From: Swâmi Petaramesh @ 2015-06-21 17:13 UTC (permalink / raw)
To: Btrfs BTRFS
Hi,
Running a 3.19 Ubuntu kernel,
I'm currently budling a RAID-1 BTRFS set for which every underlying device is
a LUKS-encrypted device itself built out of a bcache device comprised of a
mechanical HD partition + an SSD cache partition.
Looks like it's working.
BUT I see that BTRFS decides by itself to mount with the "ssd" option as
bcache makes it think the device is not "rotational".
However I feel that a mechanical HD plus SSD bcache should probably not be
"SSD-optimized" as the underlying storage is indeed mechanical and bcache
already manages the SSD part optimization by itself - and I'm afraid the "SSD
optimization" could actually cause the mechanical storage to end up being much
more fragmented than it should...
So the question is : Is there a mount option such as "nossd" that I could use
to inhibit the automatic SSD "choice" that BTRFS makes ?
TIA, kind regards.
--
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
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* Re: Is there a "nossd" option ?
2015-06-21 17:13 Is there a "nossd" option ? Swâmi Petaramesh
@ 2015-06-21 17:31 ` Roman Mamedov
2015-06-21 18:11 ` Swâmi Petaramesh
0 siblings, 1 reply; 5+ messages in thread
From: Roman Mamedov @ 2015-06-21 17:31 UTC (permalink / raw)
To: Swâmi Petaramesh; +Cc: Btrfs BTRFS
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On Sun, 21 Jun 2015 19:13:10 +0200
Swâmi Petaramesh <swami@petaramesh.org> wrote:
> Hi,
>
> Running a 3.19 Ubuntu kernel,
>
> I'm currently budling a RAID-1 BTRFS set for which every underlying device is
> a LUKS-encrypted device itself built out of a bcache device comprised of a
> mechanical HD partition + an SSD cache partition.
>
> Looks like it's working.
>
> BUT I see that BTRFS decides by itself to mount with the "ssd" option as
> bcache makes it think the device is not "rotational".
>
> However I feel that a mechanical HD plus SSD bcache should probably not be
> "SSD-optimized" as the underlying storage is indeed mechanical and bcache
> already manages the SSD part optimization by itself - and I'm afraid the "SSD
> optimization" could actually cause the mechanical storage to end up being much
> more fragmented than it should...
>
> So the question is : Is there a mount option such as "nossd" that I could use
> to inhibit the automatic SSD "choice" that BTRFS makes ?
Yes the "nossd" option (written literally like that) does in fact exist.
It would have taken you less time to try if it works, than to write this
long-winded message. :)
--
With respect,
Roman
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Is there a "nossd" option ?
2015-06-21 17:31 ` Roman Mamedov
@ 2015-06-21 18:11 ` Swâmi Petaramesh
2015-06-21 18:18 ` Eric Sandeen
2015-06-21 18:22 ` Roman Mamedov
0 siblings, 2 replies; 5+ messages in thread
From: Swâmi Petaramesh @ 2015-06-21 18:11 UTC (permalink / raw)
To: Roman Mamedov; +Cc: Btrfs BTRFS
Le dimanche 21 juin 2015 22:31:21 Roman Mamedov a écrit :
>
> Yes the "nossd" option (written literally like that) does in fact exist.
> It would have taken you less time to try if it works, than to write this
> long-winded message. :)
Possibly. Unless trying a non-existing mount option causes the mount to fail,
thus causing the system boot to fail, thus needing me to boot from a live
rescue CD... that would take much longer than writing an half-page
email ;-)
Best regards.
--
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
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* Re: Is there a "nossd" option ?
2015-06-21 18:11 ` Swâmi Petaramesh
@ 2015-06-21 18:18 ` Eric Sandeen
2015-06-21 18:22 ` Roman Mamedov
1 sibling, 0 replies; 5+ messages in thread
From: Eric Sandeen @ 2015-06-21 18:18 UTC (permalink / raw)
To: Swâmi Petaramesh; +Cc: Roman Mamedov, Btrfs BTRFS
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> On Jun 21, 2015, at 1:11 PM, Swâmi Petaramesh <swami@petaramesh.org> wrote:
>
> Le dimanche 21 juin 2015 22:31:21 Roman Mamedov a écrit :
>>
>> Yes the "nossd" option (written literally like that) does in fact exist.
>> It would have taken you less time to try if it works, than to write this
>> long-winded message. :)
>
> Possibly. Unless trying a non-existing mount option causes the mount to fail,
> thus causing the system boot to fail, thus needing me to boot from a live
> rescue CD... that would take much longer than writing an half-page
> email ;-)
>
Man pages work well too :)
http://manpages.ubuntu.com/manpages/utopic/man8/mount.8.html
Ericÿôèº{.nÇ+·®+%Ëÿ±éݶ\x17¥wÿº{.nÇ+·¥{±ý»k~Ïâ
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Is there a "nossd" option ?
2015-06-21 18:11 ` Swâmi Petaramesh
2015-06-21 18:18 ` Eric Sandeen
@ 2015-06-21 18:22 ` Roman Mamedov
1 sibling, 0 replies; 5+ messages in thread
From: Roman Mamedov @ 2015-06-21 18:22 UTC (permalink / raw)
To: Swâmi Petaramesh; +Cc: Btrfs BTRFS
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On Sun, 21 Jun 2015 20:11:25 +0200
Swâmi Petaramesh <swami@petaramesh.org> wrote:
> Le dimanche 21 juin 2015 22:31:21 Roman Mamedov a écrit :
> >
> > Yes the "nossd" option (written literally like that) does in fact exist.
> > It would have taken you less time to try if it works, than to write this
> > long-winded message. :)
>
> Possibly. Unless trying a non-existing mount option causes the mount to fail,
> thus causing the system boot to fail, thus needing me to boot from a live
> rescue CD... that would take much longer than writing an half-page
> email ;-)
mount / -o nossd,remount
works too:
[3917300.257773] BTRFS info (device dm-0): not using ssd allocation scheme
As a side note, I used this option a lot in the past to make remote block
devices such as NBD or AoE not detect as SSDs.
--
With respect,
Roman
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^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2015-06-21 18:22 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-06-21 17:13 Is there a "nossd" option ? Swâmi Petaramesh
2015-06-21 17:31 ` Roman Mamedov
2015-06-21 18:11 ` Swâmi Petaramesh
2015-06-21 18:18 ` Eric Sandeen
2015-06-21 18:22 ` Roman Mamedov
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