Optimal server (int-shop, mail server, etc.)?

Question

linux

Hi all!
Perhaps my question will seem non-trivial, and everyone has their own "taste" about the choice of server solutions, but still.
There is an existing dedicated server with 2 online shopping sites (Nginx+Php-fpm+Apache1+CMS-Bitrix). with mail for 150 users (Postfix+Dovecot-IMAP+Postgrey), and ISPmanager 4 control panel.
Task: Switch to a new server with more powerful hardware. How to do it in order not to buy a domain (it is already on the existing server, I would like to debug a new site for a start and resolve it only after all the checks), set up a mail server (transfer 50 GB of letters), a web server, etc.
What is the best way to organize a server (what programs to use? I myself am thinking of doing Front-end=Nginx, back-End=Apache), which will have 2 online stores (with a load of 10-15 thousand visits), a mail server, a WebMin panel for now, but I'm thinking of buying ISPmanager 5. (or Vestacp)
Here is the config of the new server

System hostname	Debian-84-jessie-64-LAMP 
Operating system	Debian Linux 8
Webmin version	1.791
Time on system	Fri May 13 15:48:44 2016
Kernel and CPU	Linux 3.16.0-4-amd64 on x86_64
Processor information	Intel(R) Xeon(R) CPU E5-1650 v3 @ 3.50GHz, 12 cores
System uptime	3 hours, 33 minutes
Running processes	187
CPU load averages	1.02 (1 min) 1.06 (5 mins) 1.05 (15 mins)
CPU usage	0% user, 0% kernel, 0% IO, 100% idle
Real memory	610.95 MB used, 252.32 GB total
Virtual memory	0 bytes used, 4 GB total
Local disk space	187.49 GB used, 3.58 TB total

Answer 1

What is the problem to change the records in the domain after the new server is configured. For this purpose, DNS exists - so that the name is not tied to a specific server.
For testing, you can make a third-level domain on your own.
You have big software problems if you need this server.
An online store with a load of 30,000 visitors a day perfectly lives on equipment 3 times weaker.

Answer 2

Maybe with such loads it will be better and cheaper to build your own server and buy a white static IP? Then you can increase the capacity as needed, change the percentage or throw in the operatives, in extreme cases, put 2 servers on which to take out only the database and this will greatly unload the main server.
Option on the knee:
We have (example):
1) Old server IP 10.200.50.1
2) New server IP 10.100.80.5
3) DNS records referring to the old server magaz.ru and supermagaz.ru
Do the following:
1) Dump the databases and transfer everything to a new server
2) On the new server, assign names to it as if it were on a combat server (so that the server considers that it is magaz.ru and supermagaz.ru) but do not transfer entries from the DNS hoster to this new server (DNS will tell the whole world that the sites are still at the old address).
3) On the computer \ computers from where you will debug everything in hosts (C:\Windows\System32\drivers\etc\hosts) create entries:

10.100.80.5 magaz.ru
10.100.80.5 supermagaz.ru

As a result, the whole world works in the old way with shops on the old server, and your computers from p3 work with shops on the new server, the server feels good and considers it real and combat. When you finish everything, you just change the server IP records to new ones at the DNS hoster, clients will not notice the substitution and transition at all.

Answer 3

1 variant - the fastest "Bitrix web environment" inter-inter-inter, ready.
2. Vesta variant
3. For those who know well Linux ispconfig3
now on the domain here everything is stupidly just using the same domain.
You just write it in the host files on the server and in your own.
When you get tired of testing, you delete it from the host and overwrite the real one.