[CentOS] claiming unsused space back

Tue Aug 1 13:45:58 UTC 2017
Leroy Tennison <leroy at datavoiceint.com>

I should have been more specific (and maybe ask "Are you seeing something different?")  Admittedly, Ubuntu 16.04 LTS, but the qemu-img man page says for resize (What does the CentOS7 man page say?):

resize filename [+ | -]size
           Change the disk image as if it had been created with size.

           Before using this command ... (warning about doing guest resizing first)

           After using ... (somewhat different message about guest resizing)

No mention that shrinking only works with raw, not qcow2.  Similar issue with virsh blockresize.  I probably should have been more clear that the issue isn't commands or just command options, but significant limitations in scope for some of those options.

----- Original Message -----
From: "Johnny Hughes" <johnny at centos.org>
To: "centos" <centos at centos.org>
Sent: Tuesday, August 1, 2017 6:31:14 AM
Subject: Re: [CentOS] claiming unsused space back

On 07/31/2017 05:27 PM, Leroy Tennison wrote:
> As has already been mentioned, some commands (or command options) are only supported on later releases, the man pages don't say this.  Does anyone know of a source of information listing the command, option and version it is implemented in?  That alone would be a great help.
> ----- Original Message -----
> From: "Chris Adams" <linux at cmadams.net>
> To: "centos" <centos at centos.org>
> Sent: Monday, July 31, 2017 11:45:20 AM
> Subject: Re: [CentOS] claiming unsused space back
> Once upon a time, Warren Young <warren at etr-usa.com> said:
>> Zeroing the free space not only prevents inclusion of these discarded FS blocks, they compress better, too.
> Check out the "virt-sparsify" command - it does all of this for you.

Yes .. just run man on the machine in question.  That has the commands
for the man for the version of software installed on that specific machine.

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