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Date: Tue, 05 Jun 2012 13:36:08 +0400
From: George Shuklin <george.shuklin@gmail.com>
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To: Paul Bolle <pebolle@tiscali.nl>
CC: "H. Peter Anvin" <hpa@zytor.com>, Casey Schaufler <casey@schaufler-ca.com>,
        Al Viro <viro@ZenIV.linux.org.uk>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Why minor is still 8 bit?
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On 05.06.2012 13:23, Paul Bolle wrote:
> On Tue, 2012-06-05 at 05:08 +0400, George Shuklin wrote:
>> Anyway, using LVM to provide logical volumes to customers seems be fine
>> (at least by name). But that limitation for minor is breaking whole idea.
> man 8 vgcreate reads (in part):
>      -l, --maxlogicalvolumes MaxLogicalVolumes
>          Sets the maximum number of logical volumes allowed in this
>          volume group. The setting can be changed with vgchange. For
>          volume groups with metadata in lvm1 format, the limit and
>          default value is 255. If the metadata uses lvm2 format, the
>          default value is 0 which removes this restriction: there is then
>          no limit.
>
> Doesn't that option work for you (assuming you're not stuck on lvm1
> format)? If not, where do things go wrong?
>
> (Note that I never worry about this limit, since I never use more than a
> handful of logical volumes per volume group.)
>
This is a limitaiton of LMV itself. I'm talking about making those LV 
active (visible in system). When you trying to activate too much LV, you 
will get 'device io ctl failed' message.