From: Phillip Susi <psusi@cfl.rr.com>
To: helmut@hullen.de
Cc: Helmut Hullen <Hullen@t-online.de>, linux-btrfs@vger.kernel.org
Subject: Re: Resize command syntax wrong?
Date: Wed, 30 Nov 2011 19:01:44 -0500 [thread overview]
Message-ID: <4ED6C3E8.60009@cfl.rr.com> (raw)
In-Reply-To: <ByrPr1UD1uB@helmut.hullen.de>
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On 11/30/2011 01:59 PM, Helmut Hullen wrote:
> Hallo, Phillip,
>
> Du meintest am 30.11.11:
>
>> Currently the resize command is under filesystem, and takes a path to
>> the mounted filesystem. This seems wrong to me. Shouldn't it be
>> under device, and take a path to a device to resize?
>
> No - it's a filesystem operation.
No, it isn't. You can see the function that implements the resize in the code operates on a specific disk, and the ioctl does take as an argument which disk you are trying to resize. Logically you are adjusting the space that is available on a particular device, which only indirectly affects the filesystem. In other words, the only reason that the size of the filesystem changes is because you have changed the size of a device. In fact, internally device removal is implemented by first resizing the device to 0.
It appears that the utility just passes devid=1 to the kernel when you don't specify it. It should take a dev node as an argument and translate it to the devid for you.
> p.e.
> You start with a system of 2 disks. They get filled nearly
> simultaneously.
> Then you add a 3rd disk (which is empty at that time). Now it's a good
> idea to run "balance" for equalizing the filling.
balance != resize
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next prev parent reply other threads:[~2011-12-01 0:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-30 18:47 Resize command syntax wrong? Phillip Susi
2011-11-30 18:59 ` Helmut Hullen
2011-11-30 19:15 ` Roman Mamedov
2011-11-30 19:37 ` Goffredo Baroncelli
2011-11-30 19:43 ` Helmut Hullen
2011-11-30 20:07 ` Roman Mamedov
2011-11-30 20:48 ` Goffredo Baroncelli
2011-11-30 20:55 ` Helmut Hullen
2011-12-01 0:01 ` Phillip Susi [this message]
2011-12-01 6:46 ` Helmut Hullen
2011-12-01 15:57 ` Phillip Susi
2011-12-01 16:19 ` Helmut Hullen
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