Monday, November 24, 2003, 5:44:49 PM, Nick wrote: NH> I whole heartedly agree. Intermezzo looks and feels like a research FS, NH> which its pretty darn good for. Its not a production FS at this point. ACK - but i hope drbd is better
NH> This is a little nappy if you're going to try and "cluster" these, as NH> you'll get mail showing up and disappearing based on where the user hits NH> until the rsync finishes. I don't know about anybody else, but I also NH> get nervous cron'ing an rsync which removes files. NH> Consider separating your MXs away from your mail storage boxes. NH> Yes. Double Yes. is done NH> If people are paying to access their mailbox, I disagree 100%. 3 or 4 9s NH> of availability isn't that hard to achieve with a well engineered NH> solution. However, be ready to spend the right amount of money. hehehe, this is the problem :) NH> There are several ways to solve this: NH> Shared scsi storage with active/passive failover using something in the NH> realm of Linux-HA or Veritas Cluster Services (opposite ends of the NH> price spectrum. Also opposite ends of the ability to sleep at night NH> spectrum). Simply hang an external scsi storage array (or fibre channel) NH> off of two boxes on its two channels. Then have a cluster service NH> mediating who has access to the boxes. This means one box is always NH> going to waste, something which I'm not real keen on. You can expand NH> this by having two external boxes and criss-crossing, with the ability NH> for each machine to take control of both raid's, and then offer services NH> from each with virtual IPs and fail over in each direction. NH> The other solution is to build a real cluster, with redundant storage NH> and front end machines delivering mail via NFS. Then you can abstract NH> out as many or as few functions to their own clusters, and just access NH> them via virtual IPs. NH> This is the setup I'm migrating towards, piece by piece, for my hosted NH> email platform. Right now I've got four front end smtp/pop/imap servers NH> delivering to an active/passive veritas cluster on mirrored external NH> raid (two external raid boxes mirrored in software by veritas). I'm NH> moving this to a pair of NetApp filer heads, each offering different NH> services and able to take over for each other (I feel this is less NH> wasted hardware). I'm also running a pair of fail-over capable MySQL NH> servers on my NFS servers, though those'll soon be moved off to a NH> different pair of servers with more horsepower. I'm using Linux-HA tools NH> to cluster MySQL, Veritas Foundation Suite and Cluster Server to cluster NH> NFS, and a Foundry load balancer to cluster/balance my front end NH> servers. NH> Its a rather complex setup, but so far I've got 5 9s of availability, NH> which means I get to sleep through the night, every night. NH> Hope that provides some suggestions. it does, thank you, but i guess these setups are a little to oversized for me. main problem is that i won't get a "fitting" amount of money to realize these scenarios. wen went really good with this single box for about 3 years, but recently there were some nasty down-times due to these raid problems. besides the os is a 7.x suse and a lot of patches are not aplied (no smtp.auth, but "smtp after imap" instead...), so i thought, if i have to reinstall the system i might do it with a spare server to increase the availability. NH> Obviously a lot of this can be done on a more modest, or more NH> extravagant, scale as the needs of your platform are very definitely NH> going to be different. You can get external storage really cheap these NH> days using internal IDE and external scsi interfaces (I bought a 1.2TB NH> raw unit for under $7K USD recently). Hell :) .... im talking about 700 account with about 8 Gig of imap dirs... i thought about mirroring to 40 Gig-IDE-drives... that will last for the next decade :) NH> You can build an LVS load balanced NH> cluster with pretty low end hardware that'll keep up with full 100Mbs NH> line speed. thanks for describing how it should be :) bye tom
