[Gluster-users] Fwd: Glusterfs over wan?

[Tejas N. Bhise]

Patricio,

All networked filesystems like nfs, cifs/samba and even GlusterFS can be used over WAN. The problem arises for the more complex functionality, like replication across a WAN.

Replication over WAN has different meanings for different users - some just want a good way to have a remote backup, others want a hot-cold kind of a backup so namespace issue come into the picture, but its relatively easier to solve as there is only one side active at a time. 

The most difficult one is to keep both sites active ( and R/W ) with their own full namespace and security functionality with a designated unit of the filesystem replicated. Access from each side looks like it just pulled data from its own data cache and the currency of data could move around ( potentially ) multiple locations across the globe.

I don't think anyone does that last kind of replication. AFS and DFS from the old days did go upto a certain point by providing R/O replication with remote snapshots by providing integrated multisite security and namespace, but no R/W replication. 

GlusterFS plan is to start with async WAN replication for remote backup and slowly moving into the multisite cluster architecture and active active replicated data copies with integrated namespace, which we hope to bring in with a new unified ( write ) caching.

Async WAN replication for remote backup might come in as early as end of the year with the other functionality following sometime after that.

I would like to hear more about how community users will put these different levels of WAN replication to use, how much data would change on a daily basis and hence get moved around, what kind of latency would be acceptable to your applications ? I would also like to hear if anyone is using other solutions/edge caching appliances etc to do this in other ways. 

Regards,
Tejas.

----- Original Message -----
From: "Patricio A. Bruna" <pbruna at it-linux.cl>
To: gluster-users at gluster.org
Sent: Thursday, May 27, 2010 10:00:12 PM
Subject: Re: [Gluster-users] Fwd: Glusterfs over wan?

Hi, 
just for information, what file system are available to use over WAN? 


------------------------------------ 
Patricio Bruna V. 
IT Linux Ltda. 
www.it-linux.cl 
Fono : (+56-2) 333 0578 
Móvil: (+56-9) 7776 2899 








Hi Shayn, 

The problem is not replication speed. Actually that part is just fine, and it's quite fast. 

The problem with WAN is that when the gluster client receives a request to read the file, it first checks with all the nodes in the cluster, to make sure there are no discrepancies. Only after all nodes have answered, it will read the local file (if it's replicated locally). 

Also take into account that international links are not as reliable as local LAN based links. If a node is suddenly inaccessible, it can slow down everything (again because READ operations are dependent on all nodes in the cluster answering, synchronously). 

I know that the gluster team are working on an async solution, down the road, which would make glusterfs more suitable for WAN scenarios. 

My suggestion is NOT to try it, until the gluster team officially announce WAN support. 



On May 27, 2010, at 4:31 PM, shayn at shayn.ch wrote: 

> 
> Hello ! 
> 
> sorry for english, but, just don't understand why glusterfs is not 
> destinated to be used over the wan ? 
> I think that if the files are tiny, there's no problem to use this 
> solution over wan.. ? 
> 
> But okay, if file are large.. (don't know .. 100MB - 200MB and more.) i 
> understand that it depend of the internet connection and that's the 
> replication can be so soo soo slow.. 
> 
> Please, give me some renseignments about this solution over wan 
> 
> Shayn_______________________________________________ 
> Gluster-users mailing list 
> Gluster-users at gluster.org 
> http://gluster.org/cgi-bin/mailman/listinfo/gluster-users 

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