[Gluster-users] 3.8.3 Bitrot signature process

Kotresh Hiremath Ravishankar
Mon, 19 Sep 2016 07:30:30 -0000

Hi Amudhan,

Thanks for testing out the bitrot feature and sorry for the delayed response.
Please find the answers inline.

Thanks and Regards,
Kotresh H R

----- Original Message -----
> From: "Amudhan P" <amudhan83 at gmail.com>
> To: "Gluster Users" <gluster-users at gluster.org>
> Sent: Friday, September 16, 2016 4:14:10 PM
> Subject: Re: [Gluster-users] 3.8.3 Bitrot signature process
>
> Hi,
>
> Can anyone reply to this mail.
>
> On Tue, Sep 13, 2016 at 12:49 PM, Amudhan P < amudhan83 at gmail.com
> wrote:
>
>
>
> Hi,
>
> I am testing bitrot feature in Gluster 3.8.3 with disperse EC volume 4+1.
>
> When i write single small file (< 10MB) after 2 seconds i can see bitrot
> signature in bricks for the file, but when i write multiple files with
> different size ( > 10MB) it takes long time (> 24hrs) to see bitrot
> signature in all the files.

   The default timeout for signing to happen is 120 seconds. So the signing will
happen
  120 secs after the last fd gets closed on that file. So if the file is being
written
  continuously, it will not be signed until 120 secs after it's last fd is
closed.
>
> My questions are.
> 1. I have enabled scrub schedule as hourly and throttle as normal, does
this
> make any impact in delaying bitrot signature?
      No.
> 2. other than "bitd.log" where else i can watch current status of
bitrot,
> like number of files added for signature and file status?
     Signature will happen after 120 sec of last fd closure, as said above.
     There is not status command which tracks the signature of the files.
     But there is bitrot status command which tracks the number of files
     scrubbed.

     #gluster vol bitrot <volname> scrub status


> 3. where i can confirm that all the files in the brick are bitrot signed?

     As said, signing information of all the files is not tracked.

> 4. is there any file read size limit in bitrot?

     I didn't get. Could you please elaborate this ?

> 5. options for tuning bitrot for faster signing of files?

     Bitrot feature is mainly to detect silent corruption (bitflips) of files
due to long
     term storage. Hence the default is 120 sec of last fd closure, the signing
happens.
     But there is a tune able which can change the default 120 sec but
that's only for
     testing purposes and we don't recommend it.

      gluster vol get master features.expiry-time

     For testing purposes, you can change this default and
test.
>
> Thanks
> Amudhan
>
>
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