[Gluster-users] Some Unify questions

[Deian Chepishev]

Hello Raghavendra,

Raghavendra G wrote:
> Hi Deian,
>
> On Fri, Oct 10, 2008 at 8:51 PM, Deian Chepishev 
> <dchepishev at nexbrod.com <mailto:dchepishev at nexbrod.com>> wrote:
>
>     Hi guys,
>
>     I have a few questions about UNIFY and volume creation.
>
>     You will find my config files at the end of this post. I will post my
>     questions before the config.
>
>     1. I want to use writebehind and readahead translators, because I
>     think
>     it speeds the transfer. Can you please take a look i let me know if it
>     is correctly written.
>     I basically do this:
>     create one volume from the exported bricks lets say "unify"
>     create another volume named "writebehind" with subvolumes unify
>     then create another volume named "readahead" with subvolumes
>     writebehind
>     then mount the volume named writebehind.
>
>
> If you are using  --volume-name option to glusterfs to attach to 
> writebehind, then you are bypassing readahead and hence will not get 
> readahead functionality. If you want to have both read-ahead and 
> write-behind functionalities, do not specify --volume-name option (or 
> give readahead as the argument to the option, if at all you want to 
> use it).

===> I am even more confused by your answer :).
I want to have single volume for which I want load both translators 
readahead and writebehind. That is why I thought that this is 
accomplished with the above mentioned definition scheme. Looks like I am 
wrong.

What is the correct way to define the volume in order to have both 
translators loaded for it ?

>
>
>     I have the following server and client files:
>
>
>     volume brick
>      type storage/posix
>      option directory /storage/gluster-export/data/
>     end-volume
>
>     volume brick-ns
>      type storage/posix
>      option directory /storage/gluster-export/ns
>     end-volume
>
>     ### Add network serving capability to above brick.
>
>     volume server
>      type protocol/server
>      option transport-type tcp/server
>      subvolumes brick brick-ns
>      option auth.ip.brick.allow 10.1.124. <http://10.1.124.>*
>      option auth.ip.brick-ns.allow 10.1.124. <http://10.1.124.>*
>     end-volume
>
>     =========================
>
>     Client:
>
>     volume brick1-stor01
>      type protocol/client
>      option transport-type tcp/client
>      option remote-host 10.1.124.200 <http://10.1.124.200>
>      option remote-subvolume brick
>     end-volume
>
>     volume brick1-stor02
>      type protocol/client
>      option transport-type tcp/client
>      option remote-host 10.1.124.201 <http://10.1.124.201>
>      option remote-subvolume brick
>     end-volume
>
>     volume brick-ns1
>      type protocol/client
>      option transport-type tcp/client
>      option remote-host 10.1.124.200 <http://10.1.124.200>
>      option remote-subvolume brick-ns
>     end-volume
>
>
>     volume brick-ns2
>      type protocol/client
>      option transport-type tcp/client
>      option remote-host 10.1.124.201 <http://10.1.124.201>
>      option remote-subvolume brick-ns  # Note the different remote
>     volume name.
>     end-volume
>
>     volume afr-ns
>      type cluster/afr
>      subvolumes brick-ns1 brick-ns2
>     end-volume
>
>     volume unify
>      type cluster/unify
>      option namespace afr-ns
>      option scheduler rr
>      option scheduler alu   # use the ALU scheduler
>      option alu.limits.min-free-disk  5%      # Don't create files one a
>     volume with less than 5% free diskspace
>      option alu.limits.max-open-files 10000   # Don't create files on a
>     volume with more than 10000 files open
>      option alu.order
>     disk-usage:read-usage:write-usage:open-files-usage:disk-speed-usage
>      option alu.disk-usage.entry-threshold 100GB   # Kick in if the
>     discrepancy in disk-usage between volumes is more than 2GB
>      option alu.disk-usage.exit-threshold  50MB   # Don't stop writing to
>     the least-used volume until the discrepancy is 1988MB
>      option alu.open-files-usage.entry-threshold 1024   # Kick in if the
>     discrepancy in open files is 1024
>      option alu.open-files-usage.exit-threshold 32   # Don't stop
>     until 992
>     files have been written the least-used volume
>      option alu.stat-refresh.interval 10sec   # Refresh the statistics
>     used
>     for decision-making every 10 seconds
>      subvolumes brick1-stor01 brick1-stor02
>     end-volume
>
>     volume writebehind
>      type performance/write-behind
>      option aggregate-size 512kb # default is 0bytes
>      option flush-behind on    # default is 'off'
>      subvolumes unify
>     end-volume
>
>     volume readahead
>      type performance/read-ahead
>      option page-size 512kB
>      option page-count 4
>      option force-atime-update off
>      subvolumes writebehind
>     end-volume
>


Thank you.

Regards,
Deian