[Gluster-users] 3.7.13, index healing broken?

[Dmitry Melekhov]

13.07.2016 09:04, Pranith Kumar Karampuri пишет:
>
>
> On Wed, Jul 13, 2016 at 10:29 AM, Dmitry Melekhov <dm at belkam.com 
> <mailto:dm at belkam.com>> wrote:
>
>     13.07.2016 08:56, Pranith Kumar Karampuri пишет:
>>
>>
>>     On Wed, Jul 13, 2016 at 10:23 AM, Dmitry Melekhov <dm at belkam.com
>>     <mailto:dm at belkam.com>> wrote:
>>
>>         13.07.2016 08:46, Pranith Kumar Karampuri пишет:
>>>
>>>
>>>         On Wed, Jul 13, 2016 at 10:10 AM, Dmitry Melekhov
>>>         <dm at belkam.com <mailto:dm at belkam.com>> wrote:
>>>
>>>             13.07.2016 08:36, Pranith Kumar Karampuri пишет:
>>>>
>>>>
>>>>             On Wed, Jul 13, 2016 at 9:35 AM, Dmitry Melekhov
>>>>             <dm at belkam.com <mailto:dm at belkam.com>> wrote:
>>>>
>>>>                 13.07.2016 01:52, Anuradha Talur пишет:
>>>>
>>>>
>>>>                     ----- Original Message -----
>>>>
>>>>                         From: "Dmitry Melekhov" <dm at belkam.com
>>>>                         <mailto:dm at belkam.com>>
>>>>                         To: "Pranith Kumar Karampuri"
>>>>                         <pkarampu at redhat.com
>>>>                         <mailto:pkarampu at redhat.com>>
>>>>                         Cc: "gluster-users"
>>>>                         <gluster-users at gluster.org
>>>>                         <mailto:gluster-users at gluster.org>>
>>>>                         Sent: Tuesday, July 12, 2016 9:27:17 PM
>>>>                         Subject: Re: [Gluster-users] 3.7.13, index
>>>>                         healing broken?
>>>>
>>>>
>>>>
>>>>                         12.07.2016 17:39, Pranith Kumar Karampuri
>>>>                         пишет:
>>>>
>>>>
>>>>
>>>>                         Wow, what are the steps to recreate the
>>>>                         problem?
>>>>
>>>>                         just set file length to zero, always
>>>>                         reproducible.
>>>>
>>>>                     If you are setting the file length to 0 on one
>>>>                     of the bricks (looks like
>>>>                     that is the case), it is not a bug.
>>>>
>>>>                     Index heal relies on failures seen from the
>>>>                     mount point(s)
>>>>                     to identify the files that need heal. It won't
>>>>                     be able to recognize any file
>>>>                     modification done directly on bricks. Same goes
>>>>                     for heal info command which
>>>>                     is the reason heal info also shows 0 entries.
>>>>
>>>>
>>>>                 Well, this makes self-heal useless then- if any
>>>>                 file is accidently corrupted or deleted (yes! if
>>>>                 file is deleted directly from brick this is no
>>>>                 recognized by idex heal too), then it will not be
>>>>                 self-healed, because self-heal uses index heal.
>>>>
>>>>
>>>>             It is better to look into bit-rot feature if you want
>>>>             to guard against these kinds of problems.
>>>
>>>             Bit rot detects bit problems, not missing files or their
>>>             wrong length, i.e. this is overhead for such simple task.
>>>
>>>
>>>         It detects wrong length. Because checksum won't match anymore.
>>
>>         Yes, sure. I guess that it will detect missed files too. But
>>         it needs far more resources, then just comparing directories
>>         in bricks?
>>>
>>>         What use-case you are trying out is leading to changing
>>>         things directly on the brick?
>>         I'm trying to test gluster failure tolerance and right now
>>         I'm not happy with it...
>>
>>
>>     Which cases of fault tolerance are you not happy with? Making
>>     changes directly on the brick or anything else as well?
>>
>     I'll repeat:
>     As I already said- if I for some reason ( real case can be only by
>     accident ) will delete file this will not be detected by self-heal
>     daemon, and, thus, will lead to lower replication level, i.e.
>     lower failure tolerance.
>
>
> To prevent such accidents you need to set selinux policies so that 
> files under the brick are not modified by accident by any user. At 
> least that is the solution I remember when this was discussed 3-4 
> years back.
>
So only supported platfrom is linux? Or, may be, it is better to improve 
self-healing to detect missing or wrong length files, I guess this is 
very low cost in terms of host resources operation.
Just a suggestion, may be we need to look to alternatives in near future....

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20160713/803d9397/attachment.html>