2019-01-31 08:07:07

by Xiaoguang Wang

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Subject: question about ext4 backup block group descriptors

hi,

Anyone can help answer when ext4's backup block group descriptors are updated?
I had used blktrace to track the corresponding backup block group descriptor
block, but didn't find that any backup blocks were written.
Thanks in advance.

Regards,
Xiaoguang Wang


2019-02-01 01:45:35

by Andreas Dilger

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Subject: Re: question about ext4 backup block group descriptors

On Jan 31, 2019, at 1:07 AM, Xiaoguang Wang <[email protected]> wrote:
>
> Anyone can help answer when ext4's backup block group descriptors are updated?
> I had used blktrace to track the corresponding backup block group descriptor
> block, but didn't find that any backup blocks were written.
> Thanks in advance.

The ext4 kernel code never updates the backup block group descriptors. That is only
done by e2fsck.

Cheers, Andreas





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2019-02-01 03:08:57

by Xiaoguang Wang

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Subject: Re: question about ext4 backup block group descriptors

hi,

> On Jan 31, 2019, at 1:07 AM, Xiaoguang Wang <[email protected]> wrote:
>>
>> Anyone can help answer when ext4's backup block group descriptors are updated?
>> I had used blktrace to track the corresponding backup block group descriptor
>> block, but didn't find that any backup blocks were written.
>> Thanks in advance.
>
> The ext4 kernel code never updates the backup block group descriptors. That is only
> done by e2fsck.
I see, thanks very much.

Regards,
Xiaoguang Wang

>
> Cheers, Andreas
>
>
>
>
>