Re: [IMail Forum] Imail High Availability Setup

[Ives Stoddard]

Title: Message

Randy,   Check the archives for clustering.  There has been a lot of discussion on these topics, but I haven't seen anyone implement such a configuration. due to the challenges involved:   1) File locking on shared storage devices (DAS, NAS & SAN).  All sorts of potential problems here.  While most of the time this may not be an issue, it's those rare exceptions that are difficult to manage without getting unexpected results.  This problem could be significantly reduced if IMail's storage were block-level or record level instead of file-level (as with most clustered solutions like Exchange, Domino / Notes, and even opensource like Cyrus MURDER clusters).   2) System configuration management (must duplicate registry settings between the two machines).  Configured as the same IMail 'host', or different hosts / same domain?  Whatever mechanism you use to duplicate settings will most likely involve working with the registry directly as only a subset of those keys will need to be replicated.  This becomes a particular issue for user management where settings are stored in the registry.  Would you then have to create a registry replication engine (event driven instead of batch)?  This could be improved if Ipswitch would open this up to an API that could be implemented on a shared DB backend (or LDAP, or MS AD / ADAM - ADAM is cool by the way, the beta is very interesting).   *** As our implementation is AD for integrated account authentication, I would love to see Ipswitch make use of SQL, LDAP, or MS ADAM for server configurations in an enterprise line of IMail.   3) So far as I know, the only way of effectively sharing user authentication and information is via shared SQL tables between the IMail servers.  This binds you to a particular data store, unless using a replacement LDAP DLL for the regular external DB mechanism (not really available yet, although some are tinkering).   4) You need to have an intelligent load-balancer in order to know if one of the servers has stopped functioning properly (not just simply unavailable).  With Linux LVS this is easy, but if you're running Linux why not consider something like Cyrus in the first place?   The type of functionality I believe you are looking for can be found in the following product (implemented with LDAP and *NIX).   http://www.mirapoint.com   You can get the same functionality out of Cyrus MURDER clusters.  Many larger universities are going this route because of the cost / performance value.   Give it a shot and see how it works, I think a few of us are curious to see what you come up with.  Which iSCSI products were you looking at?   -ives   ----- Original Message ----- From: Randy Leiker To: [EMAIL PROTECTED] Sent: Thursday, June 26, 2003 2:48 PM Subject: Re: [IMail Forum] Imail High Availability Setup That's true.  NAS failure is a possibility.  I've not previously heard of the RaidZone product.  I'll take a look at them & see what they have to offer.  Thanks for the tip Charles.   Randy Leiker  ( [EMAIL PROTECTED] ) Skyway Networks 816.221.1400  Ext. 100 Toll free: 1-800-538-5334 http://www.skywaynetworks.com ----- Original Message ----- From: Charles Frolick To: [EMAIL PROTECTED] Sent: Thursday, June 26, 2003 11:49 AM Subject: RE: [IMail Forum] Imail High Availability Setup Your Idea of a Dell NAS doesn't provide for HA, what if the NAS fails?  I do not remember clustering being an option for the Win Appliance OS. You would be better off looking at a soloution more like RaidZone's GangStor (http://www.raidzone.com/Products___Solutions/GangStor_Overview/gangstor_overview.html), which is fully redundant, and scaleable, I'm not sure how it handles file locks though, but, 6.06 seems to always write a lock file for all operations or rewrite the file name using a lock convention. Still not a bad Idea to have seperate spool and log directories for each server only sharing the message store.   Thanks, Chuck Frolick ArgoNet, Inc.    -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Randy Leiker Sent: Thursday, June 26, 2003 11:18 AM To: [EMAIL PROTECTED] Subject: Re: [IMail Forum] Imail High Availability Setup Len,   It's been a while since we've spoke.  Good to hear from you again & see that you're still on the Imail listserv here.  See my response below to your comments, in red: Randy Leiker  ( [EMAIL PROTECTED] ) Skyway Networks 816.221.1400  Ext. 100 Toll free: 1-800-538-5334 http://www.skywaynetworks.com What about having both Imail servers access a common storage pool via a NAS (network attached storage) appliance?  For example, some of the NAS devices I've learned about from Dell have a Windows OS on board that supposedly controls file locking.  Using gigabit Ethernet between the NAS & the Imail servers, I think that would potentially offer an adequate level of speed & prevent file collisions.    I'm thinking that a Windows powered NAS from Dell, using gigabit ethernet connectivity might be the answer for file collision management. As for the configuration mirroring, I'm planning on writing some code to use the command line utilities & Imail APIs to keep both Imail configurations in sync with each other.