After an afternoon's reading of forum posts dating back a few years, I don't see a particularly definitive answer on this. Perhaps, once my cPanel purchase is finalized, I can get official/definitive support/answer 
First, my understanding/assumptions:
- I see WHM has move a user ability, and there is mention of both a pkgacct and cpbackup script. All of them, I gather, will backup and restore "everything" related to a particular user - files, permission settings, email, mysql database, wordpress entries, etcetcetc.
- cPanel requires a license per IP address. If I were to provide HA/LB across two active/active cPanel servers, I'd need two cPanel licenses.
My fairly basic questions
1. If I use Linux LVS-DR, that requires the VIP to be present on all realservers. Can I purchase a single cPanel license tied to the VIP? Since I'd be serving all the same contents from all my realservers, would this be a problem? I don't mind buying a cPanel license for all my realservers and tying the license to each RIP instead. But the problem with doing that, I think, is each cPanel would respond to its RIP rather than a VIP and load-balancing wouldn't be -DR anymore, but maybe a -NAT type?
2. Are there better, more real-time-ish ways to backup/copy user data from one cPanel host to another? I could cronjob the pkgacct, or cpbackup. I could have my support staff manually do a copy user at the beginning of every shift, etc. But I'd rather have a way to have it a bit more realtime.
3. After (however it's done) copying a user's settings, files, databases, etc to another cPanel system, does the second cPanel system talk to its own MySQL database? For example, client A on server A has mysql database A running on mysql daemon hosted on server A. I copy user A to server B. Now server B has user A with mysql database A on the mysql daemon running on server B. And if I were to hit user A's website on server B, it would utilize the local database on server B, right? So the pkgacct or cpbackup or move user in WHM all are able to not only copy everything over, but make changes to the material being copied over to make local references? I don't expect it to go through my blah.html file and change any ahref links (say if I had it hardcoded to .../serverA/blah2.html).
I'm ok w/it being say a "primary" cPanel system and a bunch of "slaves" to share the load, so to speak. If the Mysql DB is separate from all the cPanel hosts, and say its own Mysql cluster (or replicated master/slave - I realize beyond the scope of this particular forum), would this work? I don't know what other resources that cPanel users and/or websites would write to. If I do have multiple cPanel hosts, I of course want writes to one, to be reflected to all.
Not quite fully HA/LB, but does/can cPanel insert a session/cookie or whatever type thing that an external LB could detect and use to "sticky" a session/connection to the same cPanel server? If I have the proverbial shopping cart that I start on serverB, I want to make sure that the rest of my connections from my web browser go to serverB. I suppose this should rightfully perhaps be handled at the shopping-cart/website application level rather than at the cPanel level, but I thought I'd ask.
If I take out the active/active LB part out of this, and only run active/passive HA, would the above become easier? I could copy everything from active A to passive B every ## amount of time. passive B would have a different IP address than active A. So when A goes down, I can either reset passive B to assume active A's IP address (probably the easiest/fastest) or I could have our firewall/router send all traffic destined for the now-dead-A's IP address to server B's IP address.
I'd obviously prefer an active/active HA/LB scenario. But we're more interested in HA than LB, if we had to choose.
I realize this is similar to all the "cloud" type scenarios and other questions on this forum. We do have full/root access to our entire pool of cPanel servers. We can (but haven't at this time) setup a pool of MySQL servers for HA/LB purposes. They do all have access to the same SAN.
Thank you,
PH
First, my understanding/assumptions:
- I see WHM has move a user ability, and there is mention of both a pkgacct and cpbackup script. All of them, I gather, will backup and restore "everything" related to a particular user - files, permission settings, email, mysql database, wordpress entries, etcetcetc.
- cPanel requires a license per IP address. If I were to provide HA/LB across two active/active cPanel servers, I'd need two cPanel licenses.
My fairly basic questions
1. If I use Linux LVS-DR, that requires the VIP to be present on all realservers. Can I purchase a single cPanel license tied to the VIP? Since I'd be serving all the same contents from all my realservers, would this be a problem? I don't mind buying a cPanel license for all my realservers and tying the license to each RIP instead. But the problem with doing that, I think, is each cPanel would respond to its RIP rather than a VIP and load-balancing wouldn't be -DR anymore, but maybe a -NAT type?
2. Are there better, more real-time-ish ways to backup/copy user data from one cPanel host to another? I could cronjob the pkgacct, or cpbackup. I could have my support staff manually do a copy user at the beginning of every shift, etc. But I'd rather have a way to have it a bit more realtime.
3. After (however it's done) copying a user's settings, files, databases, etc to another cPanel system, does the second cPanel system talk to its own MySQL database? For example, client A on server A has mysql database A running on mysql daemon hosted on server A. I copy user A to server B. Now server B has user A with mysql database A on the mysql daemon running on server B. And if I were to hit user A's website on server B, it would utilize the local database on server B, right? So the pkgacct or cpbackup or move user in WHM all are able to not only copy everything over, but make changes to the material being copied over to make local references? I don't expect it to go through my blah.html file and change any ahref links (say if I had it hardcoded to .../serverA/blah2.html).
I'm ok w/it being say a "primary" cPanel system and a bunch of "slaves" to share the load, so to speak. If the Mysql DB is separate from all the cPanel hosts, and say its own Mysql cluster (or replicated master/slave - I realize beyond the scope of this particular forum), would this work? I don't know what other resources that cPanel users and/or websites would write to. If I do have multiple cPanel hosts, I of course want writes to one, to be reflected to all.
Not quite fully HA/LB, but does/can cPanel insert a session/cookie or whatever type thing that an external LB could detect and use to "sticky" a session/connection to the same cPanel server? If I have the proverbial shopping cart that I start on serverB, I want to make sure that the rest of my connections from my web browser go to serverB. I suppose this should rightfully perhaps be handled at the shopping-cart/website application level rather than at the cPanel level, but I thought I'd ask.
If I take out the active/active LB part out of this, and only run active/passive HA, would the above become easier? I could copy everything from active A to passive B every ## amount of time. passive B would have a different IP address than active A. So when A goes down, I can either reset passive B to assume active A's IP address (probably the easiest/fastest) or I could have our firewall/router send all traffic destined for the now-dead-A's IP address to server B's IP address.
I'd obviously prefer an active/active HA/LB scenario. But we're more interested in HA than LB, if we had to choose.
I realize this is similar to all the "cloud" type scenarios and other questions on this forum. We do have full/root access to our entire pool of cPanel servers. We can (but haven't at this time) setup a pool of MySQL servers for HA/LB purposes. They do all have access to the same SAN.
Thank you,
PH
