Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Sorry for top posting but I'm on the blackberry. Another reason my proposal is no good is because of the cpu load on the client system. But I disagree with what you're saying. The resync would be definitely longer but mdadm is so easy to work with and does such a good job that for smaller deployments it may make more sense than drdb because it reduces the complexity of the system. ------Original Message------ From: Greg Freemyer Sender: To: Artur (eBoundHost) Cc: drbd-user at lists.linbit.com Subject: Re: [DRBD-user] iscsi + md0 = tell me why this is a bad idea Sent: Oct 21, 2008 16:36 On Tue, Oct 21, 2008 at 4:41 PM, Artur (eBoundHost) <artur at eboundhost.com> wrote: > We're getting ready to test a drbd + nfs system in production and i started > looking into iscsi. Thought of something that i couldn't find an answer to > on google, maybe i'm not looking hard enough (not on the first 5 results) > > Why not have 2 storage systems exporting iscsi and simply software md raid > the exports on a target system? This would take out complexity of drbd and > heartbeat entirely, no? > > Only thing i can think against this setup is it pushes lots of bandwidth to > both storage servers, but assuming that network is already in place this > should not be a barrier. And yes, it would require an additional 1gb nic on > the target server (1 from each storage system) > > I'm definitely not going with this setup because drbd works great, but still > looking for anything you can say about why my scenario would not be a good > idea. > -- I don't think there is anything fundamentally wrong with your solution, but... What happens when the "target" system fails. If you want high-availability, you need to implement a failover cluster for it. So now you have 2 servers on the frontend and 2 storage servers on the backend. I have an idea, lets combine the front-end and back-end servers!!! We could use this really cool technology called drbd!!! FYI: I suspect the other big issue is what happens in your model in the presence of a network failure, even if it is relatively short. I believe a typical RAID setup would immediately fail the iSCSI drive, and then when it came back online it would require a very long slow rebuild. Drbd is much more graceful in that it maintains a bitmap of out of date blocks and when the link comes back up, only those blocks are sync'ed. Greg -- Greg Freemyer Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer First 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com Best Regards, Artur eBoundHost http://www.eboundhost.com