[Gluster-users] So tangly of Glusterfs 2.0.4 distributing after dht expansion !!!!

[NovA]

Hi!

Empty files with sticky bit (access mode ---------T) are link-files,
which extended attributes contains the location of the real file. It's
OK, that these link-files have been created after changing the data
layout.
It seems you have not got the idea how the DHT works. It's rather
clear actually, as I understand it. When one accesses a file in a
GlusterFS directory the following actions are taken.  1) A special
number (hash) is generated from the file name. 2) Based on this number
a cluster subvolume is chosen where to look the file's data. 3) The
data is transfered form/to the selected subvolume. 3a) Instead of the
real data, the selected subvolume can contain a link to the other
subvolume where the data really resides, then the data transfered
from/to there.
The algorithm of choosing a subvolume by hash (in the 2nd item)
depends on the total number of available subvolumes. So it will select
different subvolumes if the number changes. To ensure availability of
files created in previous layout GlusterFS creates link-files, which
you see.

Best wishes,
  Andrey

2009/7/14 eagleeyes <eagleeyes at 126.com>:
> HI:
>    Today  i tested glusterfs2.0.4 with  fuse-2.8.0-pre3 , for dht expansion
> . I found a  problem.
>     I use
> [root at nio1 data6]# ls /data/
> data1  data2  data3  data4  data5  data6  as data dir ,
>
> first i  used data1+data2+data3  ,mount dot /mnt  and touch
> 11  22  33  44  55  66   , created "ddd  eee  jjj  pppppp  uuu  yy " with
> some word in them .
>         then those files  in data was :
>
> ll -h /data/*
> /data/data1:
> total 0
> -rw-r--r-- 1 root root 0 Jul 14 17:14 11
> -rw-r--r-- 1 root root 0 Jul 14 17:14 33
> /data/data2:
> total 12K
> -rw-r--r-- 1 root root   0 Jul 14 17:14 22
> -rw-r--r-- 1 root root   0 Jul 14 17:14 44
> -rw-r--r-- 1 root root 116 Jul 14 17:15 ddd
> -rw-r--r-- 1 root root 116 Jul 14 17:15 jjj
> -rw-r--r-- 1 root root 116 Jul 14 17:15 yy
> /data/data3:
> total 12K
> -rw-r--r-- 1 root root   0 Jul 14 17:14 55
> -rw-r--r-- 1 root root   0 Jul 14 17:14 66
> -rw-r--r-- 1 root root 116 Jul 14 17:15 eee
> -rw-r--r-- 1 root root 116 Jul 14 17:15 pppppp
> -rw-r--r-- 1 root root 116 Jul 14 17:15 uuu
>
> and then  i expansion dht client, used data1+data2+data3+data4+data5+data6
> ,mount dot /mnt
> this time  i find
> ll -h /data/*
> /data/data1:
> total 0
> -rw-r--r-- 1 root root 0 Jul 14 16:57 11
> -rw-r--r-- 1 root root 0 Jul 14 16:57 33
> /data/data2:
> total 16K
> ---------T 1 root root   0 Jul 14 16:58 11
> -rw-r--r-- 1 root root   0 Jul 14 16:57 22
> -rw-r--r-- 1 root root   0 Jul 14 16:57 44
> -rw-r--r-- 1 root root 126 Jul 14 16:56 ddd
> -rw-r--r-- 1 root root 126 Jul 14 16:56 jjj
> -rw-r--r-- 1 root root 126 Jul 14 16:56 yy
> /data/data3:
> total 24K
> ---------T 1 root root   0 Jul 14 16:58 44
> -rw-r--r-- 1 root root   0 Jul 14 16:57 55
> -rw-r--r-- 1 root root   0 Jul 14 16:57 66
> ---------T 1 root root   0 Jul 14 16:58 ddd
> -rw-r--r-- 1 root root 126 Jul 14 16:56 eee
> ---------T 1 root root   0 Jul 14 16:58 jjj
> -rw-r--r-- 1 root root 126 Jul 14 16:56 pppppp
> -rw-r--r-- 1 root root 126 Jul 14 16:56 uuu
> /data/data4:
> total 8.0K
> ---------T 1 root root 0 Jul 14 16:58 22
> ---------T 1 root root 0 Jul 14 16:58 yy
> /data/data5:
> total 4.0K
> ---------T 1 root root 0 Jul 14 16:58 55
> /data/data6:
> total 16K
> ---------T 1 root root 0 Jul 14 16:58 66
> ---------T 1 root root 0 Jul 14 16:58 eee
> ---------T 1 root root 0 Jul 14 16:58 pppppp
> ---------T 1 root root 0 Jul 14 16:58 uuu
>
> files' names  appeared in data4 data5 data6 ,but no byte . Why was it ?
> If a directory  i can comprehend ,but those was files  and  appeared files
> was not all files in  data1+data2+data3  .
> Why  the files distributing was  so tangly .
>
> 2009-07-14
> ________________________________
> eagleeyes
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