[DRBD-user] DRBD over a WAN, alternatives?

drbd at bobich.net drbd at bobich.net
Fri Mar 21 16:27:25 CET 2008

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

> I'm happily using DRBD on a local cluster of systems, with both nodes 
> writable and ocfs2 as the filesystem. It works great.
> I'm looking at making this cluster geographically diverse, with each end 
> having a 100mbit link to the internet.


> I'm also wondering if anyone has experience (or even names) of other products 
> that can do replication to 2+ nodes, have it writable on both sides, etc. I'm 
> familiar with PeerFS and Constasnt Replicator (owned by some other compoany 
> now), but would love to hear any experiences or any other apps that will do 
> this.

You may want to look into Coda. It's supposed to be for exactly this sort 
of thing, but there is one limitation that kills it for most of my 
intended uses: 1MB limit for metadata on directories. This 1MB includes 
all file names and attributes in a directory. This translates to about 
4,000-10,000 files per directory, which makes it unsuitable for some 
purposes (e.g. large Maildirs). The only other thing that takes some 
getting used to is that it doesn't use the standard POSIX 
security/ownership semantics - it uses ACLs (a bit like SE Linux).

If neither of these are a problem for you, itmay just be what you are 
after. The nice thing about it is that it replicates files on close, which 
makes performance bearable over a WAN.

GlusterFS may be another option.

Good luck.


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