Question of online defrag, thanks

Question of online defrag, thanks

[Ming Lei]

Hi,

I am using e4defrag to defrag running ext4 online.
During running e4defrag, I am writing/reading data on file system.
Is it safe to use e4defrag? I mean if power failure happens, is there any possibility of data loss or defragging file corruption?
If there is possibility of defragging file corruption after power failure, can fsck fix it?

Thank you very much.
Peng

Re: Question of online defrag, thanks

[Akira Fujita]

Hello Ming,
 
> During running e4defrag, I am writing/reading data on file system.
> Is it safe to use e4defrag? I mean if power failure happens, is there any possibility of data loss or defragging file corruption?

# I have received same question from Peng and I already answered him. Anyway;

The journal feature and kernel internal locks protect data corruption
against power failure and R/W confliction on ext4, so you don't need to
worry about that.

For more detail about journal, please check
the following web page.

https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#Journal_.28jbd2.29

Regards,
Akira Fujita

(2013/10/29 2:13), Ming Lei wrote:
> Hi,
> 
> I am using e4defrag to defrag running ext4 online.
> During running e4defrag, I am writing/reading data on file system.
> Is it safe to use e4defrag? I mean if power failure happens, is there any possibility of data loss or defragging file corruption?
> If there is possibility of defragging file corruption after power failure, can fsck fix it?
> 
> Thank you very much.
> Peng
> 
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