Gluster users - May 2017 - Add single server

2017-05-01 19:12 GMT+02:00 Pranith Kumar Karampuri <pkarampu at
redhat.com>:
> I agree it should. Question is how? What will be the resulting brick-map?
This is why i'm suggesting to add a file mapping somewhere.
You could also use xattr for this:

"file1" is mapped to GFID, then, as xattr for that GFID, you could
save the server/brick location, it this
way you always know where a file is.

To keep it simple for non-developers like me (this is wrong, it's a
simplification):
"/tmp/file1" hashes to 306040e474f199e7969ec266afd10d93

hash starts with "3" thus is located on brick3

You don't need any metadata for this, the hash algoritm is the only
thing you need.

But if you store the file location mapping somewhere (in example as
xattr for the GFID file) you can look for the file without using the
hash algoritm location.

ORIG_FILE="/tmp/file1"
GFID="306040e474f199e7969ec266afd10d93"
FILE_LOCATION=$(getfattr -n "file_location" $GFID)

if $FILE_LOCATION
   read from $FILE_LOCATION
else
   read from original algoritm

On Mon, May 1, 2017 at 10:57 PM, Gandalf Corvotempesta <
gandalf.corvotempesta at gmail.com> wrote:
> 2017-05-01 19:12 GMT+02:00 Pranith Kumar Karampuri <pkarampu at
redhat.com>:
> > I agree it should. Question is how? What will be the resulting
brick-map?
>
> This is why i'm suggesting to add a file mapping somewhere.
> You could also use xattr for this:
>
> "file1" is mapped to GFID, then, as xattr for that GFID, you
could
> save the server/brick location, it this
> way you always know where a file is.
>
To know GFID of file1 you must know where the file resides so that you can
do getxattr trusted.gfid on the file. So storing server/brick location on
gfid is not getting us much more information that what we already have.

>
> To keep it simple for non-developers like me (this is wrong, it's a
> simplification):
> "/tmp/file1" hashes to 306040e474f199e7969ec266afd10d93
>
> hash starts with "3" thus is located on brick3
>
> You don't need any metadata for this, the hash algoritm is the only
> thing you need.
>
> But if you store the file location mapping somewhere (in example as
> xattr for the GFID file) you can look for the file without using the
> hash algoritm location.
>
> ORIG_FILE="/tmp/file1"
>
> GFID="306040e474f199e7969ec266afd10d93" <<---- How did we
get GFID?
>
May be I didn't understand your solution properly.

> FILE_LOCATION=$(getfattr -n "file_location" $GFID)
>
> if $FILE_LOCATION
>    read from $FILE_LOCATION
> else
>    read from original algoritm
>


-- 
Pranith
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.gluster.org/pipermail/gluster-users/attachments/20170501/41930d69/attachment.html>