[Gluster-users] question about glusterfs use

[Keith Freedman]

I'm currently using gluster in a webserver environment.  It's mostly 
ok, some stability issues but I think they'll be resolved when 1.4 goes stable.

comments inline below:

At 05:19 AM 9/18/2008, Monchanin Eric wrote:
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>I am trying to find a way to "unify" 2 or 3 servers (hopefully more in
>the future) to host our website's users' content ( the files are
>between a few kB to a few MB ).
>The servers are located in 2 different places (different countries)
>because they both host applications that run "locally".

you're going to have severe performance issues with having things so 
far apart.  You're also highly at risk of network interruptions so 
you really need a solution that can handle loosing contact with the 
other server.

NFS wont do this for you at all, nor will sshfs.
Basically you need to replicate rather than unify.  (You could do 
both), but you will need to make sure that there are local copies of 
all data or you will be down during a network interruption.

>My first idea was to simply mount via NFS, sshfs or some other better
>way a "user" directory hosted in the second country, but that is only
>temporary, and not very good.
>Then I discovered there was something called distributed file systems,
>and I am now experimentating various ways to achieve my goald : have a
>DFS hosting all my users contents, wherever the servers are in the
>world, with some redundancy when we'll have enough servers to avoid
>data loss.

if the data is primarily read only and changes infrequently, you may 
be able to get away with an rsync based solution (I use Unify to sync 
the non-time sensitive files, like email accounts and password files, 
etc... and unison for the user home/webroot files.
so if your data isn't time sensitive or is updated infrequently this 
is probably an ideal solution, it's low bandwidth, and not dependant 
on a network.

>On another part, I would like one of my servers to host only files
>from a certain user (specific directory 'for instance, path looks like
>'users/users123'), though I'd like these files to be also stored on my
>local server (has a local backup).

I belive you can do this with unison, some of the translators let you 
specify this, although you may just need to run multiple gluster 
clients/servers for each of the users, but ultimately you can somehow 
accomplish this with gluster.

>I've seen it was apparently possible using something close to that in
>the client config :
>
>volume unify
>      type cluster/unify
>      option namespace client-1
>      option scheduler switch
>      option switch.case *users/users123*:remote_server local_server
>      subvolumes remote_server local_server
>end-volume

this might work, or perhaps instead of having users as your gluster 
bricks, you have a separate config for each user.
I'm not sure what sort of resource overhead this would create, it's 
probably negligible relative to the flexibility.

Gluster/AFR would do what you need, there would be some network 
latency issues with the servers being in different countries.  every 
file access the server has to check the other one to make sure it's 
got the latest files (You obviously have this with NFS, etc. also) 
which may make things realllly slow, but it's worth testing out at least.
I'd wait for 1.4 which has the binary protocol and, therefor, smaller 
network packets.  It also seems to have some significant AFR improvements.



>So, anyway, thank you for your time,
>
>Eric
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