[Lustre-discuss] Gluster then DRBD now Lustre?

[Cliff White]

nathan at robotics.net wrote:
> On Mon, 16 Jun 2008, Kilian CAVALOTTI wrote:
> 
>> On Monday 16 June 2008 11:40:40 am Andreas Dilger wrote:
>>>> NYC == New York City?  What
>>>> is SJC?
>>> SJC == San Jose, California
>> That's why I thought, but if so, the following part loses me:
>>
>>> This is working in a test setup, however there are some down sides.
>>> The first is that DRBD only supports IP, so we have to run IPoIB over
>>> our our infiniband adapters, not an ideal solution.
>> Nathan, you won't be able to use Infiniband between Ney Work City and
>> San Jose, CA, anyway, right? Even without considering IB cables' length
>> limitation, and unless you can use some kind of dedicated,
>> special-purpose link between your sites, the public Internet is not
>> really able to provide bandwidth nor latencies compatible with
>> Infiniband standards.
> 
> Ok, so in the original email east to west was what we originally wanted to 
> do but realized that would not be possible because of round trip delay 
> even over gig e. Instead of mirroring our traffic east west we are starting 
> with 2 servers in each location tied together with Infiniband. The 
> infiniband cables are only 5M. : ) Currently we are mirroring traffic with 
> DRBD between the two local systems in each datacenter, but we are looking 
> for the tradeoffs of switching to Lustre since DRBD does not support 
> Infiniband.
> 

Umm....Lustre is not a replacement for DRBD, so we're very confused over 
here. Lustre is a way of making a big distributed filesystem out of a 
bunch of storage nodes. We don't do replication, it's basically RAID 0.

So, you could use Lustre to make one big filesystem out of two local 
servers. You could even make one big filesystem out of your multiple 
locations over the WAN (it's been done).

But, you can't use Lustre to mirror data. (yet, wait a year)

So I think your Gluster expedition might have confused you. Gluster and 
Lustre are only words that sound somewhat the same, there is _no_ 
relationship between the two. (except the fact that there is some 
filesystem goop involved) You're comparing apples to knee socks if you 
are attempting to map gluster experience to a Lustre setup.

cliffw

> -Nathan
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