[sheepdog] [PATCH V4 2/2] collie: optimize 'collie vdi check' command

[Yunkai Zhang]

On Mon, Sep 3, 2012 at 8:40 PM, MORITA Kazutaka
<morita.kazutaka at lab.ntt.co.jp> wrote:
> At Mon, 3 Sep 2012 20:11:48 +0800,
> Yunkai Zhang wrote:
>>
>> On Mon, Sep 3, 2012 at 7:46 PM, Liu Yuan <namei.unix at gmail.com> wrote:
>> > On 09/03/2012 07:12 PM, Yunkai Zhang wrote:
>> >> On Mon, Sep 3, 2012 at 7:03 PM, Liu Yuan <namei.unix at gmail.com> wrote:
>> >>> On 09/03/2012 06:54 PM, Yunkai Zhang wrote:
>> >>>> We can compare this result with comand line tools: sha1sum, which can
>> >>>> also help us to verify program's correction I think.
>> >>>
>> >>> Could you specify a use case for this? I have no idea how end users can
>> >>> make use of sha1 string. For a crashed cluster, I think want users need
>> >>> to do is, run check to restore cluster consistency by one command like fsck.
>> >>
>> >> Our root problem is just why we need to move sha1_to_hex from
>> >> farm/sha1_file.c to lib/sha1.c, does this change bother you?
>> >>
>> >
>> > Of course, it is ugly. Sha1 is only used in Farm, moving it out of Farm implementation
>> > is nonsense to me.
>> >
>> >> Show sha1 string will make the output more meaningful for us, why need
>> >> to a use case? It's a so small/simple thing, do you like argue
>> >> everything?
>> >>
>> >
>> > 1) it is my duty to review patches and whoever tries to move sha1_to_hex() out of
>> > sha1_file.c, I will ask why he needs it and verify if it is a reasonable movement.
>> > 2) it is you who always take patch comments as malicious argument which is meant to
>> > be against you but in fact only meaningful to patch itself.
>>
>> You misunderstand me, I didn't take any comments as malicious argument
>> for me, what I think is that you spend so much time to discuss those
>> triviality.
>>
>> Don't you think 'Move sha1.c from farm/sha1_file.c to lib/sha1.c' is
>> worth discussing? Time is very precious for us, does it?
>
> If we need the function outside farm, it is okay to move it to
> lib/sha1.c.  I think what Yuan want to know is that how it will help
> users to print sha1 values in the collie outputs.  What is the
> situation users want to compare hash strings?

What the original purpose of this patch is to let user see the
different replicas of inconsistent object, instead of repairing it
directly.

This patch can help us to test cluster's consistency:
1. We need not to write shell script to read raw objects and compare
it from each node, especially in a big cluster, using shell to compare
is not efficient.

2. This patch can help me to test code when develop program, it can
use to check 'delay recovery' which may lead to inconsistency when
implement incorrectly. Printing sha1 in output, and comparing this
value with sha1sum's output, It can help us to verity program's
correction (I have mentioned it in previous email).

>
> Thanks,
>
> Kazutaka



-- 
Yunkai Zhang
Work at Taobao