Pranith Kumar Karampuri
2016-Jul-13 05:04 UTC
[Gluster-users] 3.7.13, index healing broken?
On Wed, Jul 13, 2016 at 10:29 AM, Dmitry Melekhov <dm at belkam.com> wrote:> 13.07.2016 08:56, Pranith Kumar Karampuri ?????: > > > > On Wed, Jul 13, 2016 at 10:23 AM, Dmitry Melekhov < <dm at belkam.com> > dm at belkam.com> wrote: > >> 13.07.2016 08:46, Pranith Kumar Karampuri ?????: >> >> >> >> On Wed, Jul 13, 2016 at 10:10 AM, Dmitry Melekhov < <dm at belkam.com> >> dm at belkam.com> wrote: >> >>> 13.07.2016 08:36, Pranith Kumar Karampuri ?????: >>> >>> >>> >>> On Wed, Jul 13, 2016 at 9:35 AM, Dmitry Melekhov < <dm at belkam.com> >>> dm at belkam.com> wrote: >>> >>>> 13.07.2016 01:52, Anuradha Talur ?????: >>>> >>>>> >>>>> ----- Original Message ----- >>>>> >>>>>> From: "Dmitry Melekhov" < <dm at belkam.com>dm at belkam.com> >>>>>> To: "Pranith Kumar Karampuri" < <pkarampu at redhat.com> >>>>>> pkarampu at redhat.com> >>>>>> Cc: "gluster-users" < <gluster-users at gluster.org> >>>>>> 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 ?????: >>>>>> >>>>>> >>>>>> >>>>>> 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. -- Pranith -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20160713/ea55e40b/attachment.html>
13.07.2016 09:04, Pranith Kumar Karampuri ?????:> > > 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 ?????: >> >> >> 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 ?????: >>> >>> >>> 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 ?????: >>>> >>>> >>>> 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 ?????: >>>> >>>> >>>> ----- 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 >>>> ?????: >>>> >>>> >>>> >>>> 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>