[Gluster-devel] Fwd: [Gluster-users] Self heal files

jayakrishnan mm jayakrishnan.mm at gmail.com
Tue Feb 14 07:31:19 UTC 2017


On Mon, Feb 13, 2017 at 7:07 PM, Krutika Dhananjay <kdhananj at redhat.com>
wrote:

> Hi JK,
>
> On Mon, Feb 13, 2017 at 1:06 PM, jayakrishnan mm <
> jayakrishnan.mm at gmail.com> wrote:
>
>> Hi Krutika,
>> Could you pls. tell me what is the meaning of base file name ? I mean the
>> part after xattrop-* what do  this number signify ?
>>
>> Ex: xattrop-*a321b856-05b3-48d3-**a393-805be83c6b73 . *Is this gfid  of
>>  some file ?
>>
>
> No. *a321b856-05b3-48d3-**a393-805be83c6b73 *is a randomly UUID.
> So in order to not consume one on-disk inode per index, index translator
> creates this one base file called xattrop-xxxxxxxxx....xxx of size 0 bytes
> where xxxxxxxx.....xxx is a randomly generated UUID and all indices that
> need to be created to signify that certain gfids need heal will be
> hard-linked to
> this base file. So the number of inodes consumed will remain 1,
> irrespective of
> whether 10 files need heal or a 100 or 1000 or even a million.
> You can do an `ls -li` under xattrop directory where a couple of files
> need heal
> to see it for yourself.
>

Understood. So all  files will have gfid entries inside .glusterfs/xx/yy ,
where xx/yy  is the initial part of gfid.
Only those need healing are kept under xattrop directory, and in order to
save inodes, they are hard linked to a base file .
And  self heal daemon can traverse  this directory later  for the purpose
of healing.

I have encountered some extra gfids

*Volume Name: rep-vol*
*Type: Replicate*
*Volume ID: 8667044d-b75e-4fc0-9ae8-2d2b39b8558f*
*Status: Started*
*Number of Bricks: 1 x 2 = 2*
*Transport-type: tcp*
*Bricks:*
*Brick1: 192.168.36.220:/home/user/gluster/rep-brick1*
*Brick2: 192.168.36.220:/home/user/gluster/rep-brick2*
*Options Reconfigured:*
*performance.readdir-ahead: on*

*I kill  brick1 process, so that status is as below*

Status of volume: rep-vol
Gluster process                             TCP Port  RDMA Port  Online  Pid
------------------------------------------------------------
------------------
Brick 192.168.36.220:/home/user/gluster/rep
-brick1                                     N/A       N/A        N
N/A
Brick 192.168.36.220:/home/user/gluster/rep
-brick2                                     49221     0          Y
24925
NFS Server on localhost                     N/A       N/A        N
N/A
Self-heal Daemon on localhost               N/A       N/A        Y
24954

Task Status of Volume rep-vol
------------------------------------------------------------
------------------
There are no active volume tasks

*Copy  wish.txt  to /mnt/gluster/rep (mount  point)*

*root at dhcp-192-168-36-220:/home/user/gluster/rep-brick2/.glusterfs/indices/xattrop#
ls -li*
*total 0*
*3670235 ---------- 3 root root 0 Feb  9 07:04
00000000-0000-0000-0000-000000000001*
*3670235 ---------- 3 root root 0 Feb  9 07:04
a3e23755-4ec6-42d2-ac2c-ad4bd682cdbd*
*3670235 ---------- 3 root root 0 Feb  9 07:04
xattrop-8263faed-cba8-4738-9197-93e4e7e103ff*

*As expected.*

*Now I create  another file  test.txt  on the mount point.*

*root at dhcp-192-168-36-220:/home/user/gluster/rep-brick2/.glusterfs/indices/xattrop#
ls -li*
*total 0*
*3670235 ---------- 7 root root 0 Feb  9 07:04
00000000-0000-0000-0000-000000000001*
*3670235 ---------- 7 root root 0 Feb  9 07:04
571ca3f1-5c1b-426d-990e-191aa62ea9c4*
*3670235 ---------- 7 root root 0 Feb  9 07:04
6b7f7823-b864-4f48-8a07-7c073f8d2ef5*
*3670235 ---------- 7 root root 0 Feb  9 07:04
7b4e97fc-8734-4dba-a72a-a750a22abd2d*
*3670235 ---------- 7 root root 0 Feb  9 07:04
96587bb0-2ff8-4d97-8470-69bb48be9fd2*
*3670235 ---------- 7 root root 0 Feb  9 07:04
a3e23755-4ec6-42d2-ac2c-ad4bd682cdbd*
*3670235 ---------- 7 root root 0 Feb  9 07:04
xattrop-8263faed-cba8-4738-9197-93e4e7e103ff*

root at dhcp-192-168-36-220:/home/user/gluster/rep-brick2/.glusterfs/indices/xattrop#
getfattr -d -e hex -m . ../../../wish.txt  | grep gfid
trusted.gfid=*0xa3e237554ec642d2ac2cad4bd682cdbd*
root at dhcp-192-168-36-220:/home/user/gluster/rep-brick2/.glusterfs/indices/xattrop#
getfattr -d -e hex -m . ../../../test.txt  | grep gfid
trusted.gfid=*0x571ca3f15c1b426d990e191aa62ea9c4*


*Why  some extra  gfids?*

Regards
JK



>
> -Krutika
>
>
>> Regards
>> JK
>>
>>
>> On Tue, Apr 19, 2016 at 12:31 PM, jayakrishnan mm <
>> jayakrishnan.mm at gmail.com> wrote:
>>
>>> OK.
>>> On Apr 19, 2016 11:25 AM, "Krutika Dhananjay" <kdhananj at redhat.com>
>>> wrote:
>>>
>>>> The hardlink will be removed, yes, but the base file will stay.
>>>>
>>>> -Krutika
>>>>
>>>> On Tue, Apr 19, 2016 at 8:31 AM, jayakrishnan mm <
>>>> jayakrishnan.mm at gmail.com> wrote:
>>>>
>>>>> Hi,
>>>>> Is the hardlink  not  removed, after  healing  is  done ?
>>>>>
>>>>> --JK
>>>>>
>>>>>
>>>>> On Mon, Apr 18, 2016 at 6:22 PM, Krutika Dhananjay <
>>>>> kdhananj at redhat.com> wrote:
>>>>>
>>>>>> That's just a base file that all the gfid files are hard-linked to.
>>>>>> Since it is pointless to consume one inode for each gfid that needs a
>>>>>> heal, we use a base file
>>>>>> with an identifiable name (xattrop-*) and then hard-link the actual
>>>>>> gfid files representing pointers for heal
>>>>>> to this file.
>>>>>>
>>>>>> -Krutika
>>>>>>
>>>>>> On Mon, Apr 18, 2016 at 11:00 AM, jayakrishnan mm <
>>>>>> jayakrishnan.mm at gmail.com> wrote:
>>>>>>
>>>>>>> Hi,
>>>>>>> Self  healing daemon refers  to .glusterfs/indices/xattrop
>>>>>>> directory  to see the  files  which  are  to  be  healed, and  these  dir
>>>>>>> should  contain gfids  of those  files.
>>>>>>>
>>>>>>> I see  some  other ids  also which are  prefixed  with  xattrop-  ,
>>>>>>> for example :
>>>>>>>
>>>>>>> root at ad3:/data/ssd/dsi-ec8-brick/.glusterfs/indices/xattrop# ll
>>>>>>> total 8
>>>>>>> drw------- 2 root root 4096 Apr  8 10:53 ./
>>>>>>> drw------- 3 root root 4096 Apr  8 10:53 ../
>>>>>>> ---------- 1 root root    0 Apr  8 10:53
>>>>>>> xattrop-a321b856-05b3-48d3-a393-805be83c6b73
>>>>>>>
>>>>>>> What  is the  meaning ?
>>>>>>>
>>>>>>>
>>>>>>> Best Regards
>>>>>>> JK
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Gluster-users mailing list
>>>>>>> Gluster-users at gluster.org
>>>>>>> http://www.gluster.org/mailman/listinfo/gluster-users
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>
>
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