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From:   Andreas Dilger <adilger@dilger.ca>
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Subject: Re: Is it safe to use the bigalloc feature in the case of ext4
 filesystem?
Date:   Tue, 27 Jul 2021 00:24:45 -0600
In-Reply-To: <0dc45cbd-b3b0-97ab-66a9-f68331cb483e@gmail.com>
Cc:     linux-ext4@vger.kernel.org
To:     Mikhail Morfikov <mmorfikov@gmail.com>
References: <0dc45cbd-b3b0-97ab-66a9-f68331cb483e@gmail.com>
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On Jul 23, 2021, at 9:30 AM, Mikhail Morfikov <mmorfikov@gmail.com> wrote:
> 
> In the man ext4(5) we can read the following:
> 
>    Warning: The bigalloc feature is still under development,
>    and may not be fully supported with your kernel or may
>    have various bugs. Please see the web page
>    http://ext4.wiki.kernel.org/index.php/Bigalloc for details.
>    May clash with delayed allocation (see nodelalloc mount
>    option).
> 
> According to the link above, the info is dated back to 2013,
> which is a little bit ancient.
> 
> What's the current status of the feature? Is it safe to use
> bigalloc on several TiB hard disks where only big files will be
> stored?

Hi Mikhail,
I am not using bigalloc myself (and I'm not aware of its use with
any Lustre-releated ext4 filesystems), but I believe that bigalloc
is in use at some other large storage sites.  Hopefully someone
that is using it can respond here (this may be slow due to summer
vacation).

Cheers, Andreas


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