Author Topic: MEM is moving...  (Read 3573 times)

Offline AdeV

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MEM is moving...
« on: January 29, 2013, 11:15:59 AM »
...to a shiny new webspace account...

As you may have noticed recently, MEM has been subject to too much unexpected downtime. The reason is the server it is living on crashing - but the actual cause of that crashing remains a mystery; and I have neither the time nor the skills to sort it out.

As a result, instead of living on a dedicated server, we are moving to a hosting site. This should achieve 2 objectives : 1 - the server will no longer crash, and 2 - if it does, I can go shout at someone else, instead of having to shout at myself...


I plan to start the move early on Sunday 3rd Feb (all times are GMT).

At approximately 7am, the forum will be put into maintenance mode. I'm not sure what happens to half-written posts when I do this, I suspect you don't get to finish off... if that is the case, sorry.
7:15: I will begin transferring the attachments folder (all those pictures and plans), this will take around an hour.
8:15: I will transfer the database. Experience suggests this will take anything between 15 and 45 minutes.
9:00: Hopefully, the system & all data is now transferred. I will do some routine testing on the new forum to make sure posting is OK, etc.
9:30: If all went well, I will alter the DNS record to point to the new server, make the final configuration changes, then open the new forum for business.

Because of the way name resolution works on the internet, it might take up to 48 hours for your computer to see the new address. However, there are a couple of tricks you can use to speed this up, I will add these to this thread in the next day or so.

The old forum will remain in "maintenance mode" until it is no longer getting any hits, at which point we can delete it.

If, at any point during the upgrade, things go badly pear shaped, then I will abort the move & re-open the forum, with an announcement to suit. I will alter the maintenance message if the move has been successful, so wait for that new message before you start changing DNS records...

If there are any questions or comments, please use this thread in chatterbox.
Cheers,
Ade
--
I'm just a poor old man. I have no time for law-breakers. My legs are grey. My ears are gnarled. My eyes are old and bent.

Offline AdeV

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Dodging DNS, or, how to get your MEM fix on Sunday morning (GMT)
« Reply #1 on: February 01, 2013, 07:35:25 PM »
DNS (Domain Name Service) records are how t'interwebs sites, like this one, find their way onto your computer. You type "www.modelenginemaker" into your browser, and under the skin, all kinds of trickery goes on to turn that name into a "dotted quad" set of numbers, which is the internet address of this site. The request then goes through a bunch of routers, each of which knows the next part of the journey.

As you can probably imagine, there are millions - maybe billions - of DNS records out there. In order to prevent DNS servers from melting under the load of all their requests, they work as follows:

1) You request www.modelenginemaker.com from your local DNS server. It doesn't know the answer, so it goes and asks a "root server", which tells it to go as another server, which ..... eventually, your DNS server asks the hosting DNS server, which gives the right answer.
2) Your DNS server saves the result in its short-term cache.
3) Next time you ask (i.e. next time you click a link or whatever), your DNS server remembers the answer & tells you, without all that tedious looking up stuff.
4) After 12-48 hours, depending on how it's configured, it forgets the answer, and next time you ask it has to look it up again.

So, as you can probably tell by now, when I change the DNS record on Sunday morning, your DNS server will keep giving the old answer, for anything up to 48 hours.

2 days without MEM. Could you really cope? I couldn't.....


So... here's a little trick to "fool" your computer into going to the RIGHT place.  There's one thing to remember - DON'T make this change until you are SURE that the new forum is up & running and ready to use. I will tell you it is via the "closed for maintenance" message on THIS (the soon to be old) forum.... Trust me, it'll make sense on the day.

The trick varies slightly depending on what version of Windows or Linux you use. Apple guys, sorry, I can't help you, if anyone knows where the "hosts" file is on Apple computers, PM me and I will add it here.

Step 1: Find your "hosts" file

On Windows XP, and Windows 8 (and, therefore I assume on Vista & Windows 7), it is in the c:\windows\system32\drivers\etc folder.
On Linux machines, it's usually /etc/hosts

Step 2: Open "hosts" using a text editor, e.g. notepad on Windows, nano or vi or gedit on Linux

It will look something like the 1st attachment to this post.

Go to the very end of the file, and add a line like this:

195.26.90.15     www.modelenginemaker.com

Step 3: Save the file....

Windows XP users, just save the file & close it. Same for Linux users.

Windows Vista/7/8 users, I'm afraid there's a few hoops to jump through.....
a) Save the file to your Documents folder, call it hosts.txt
b) You need to re-name the file to get rid of the .txt extension; the EASIEST way is to find the Folder Options dialog (View menu -> Options -> Change Folder And Search Options on Windows 8 - see attached pic 2), on the View tab find the option "Hide extension for known file types", and un-tick it, save & close the dialog. You can now see (and remove) the .txt extension. I assume Vista & Win 7 are similar. See pic 3 for the Windows XP dialog, it looks very similar in Win8
b2) Alternatively, open a command prompt, use the CD command to change directory to your Documents folder, and the REN command to rename hosts.txt to host (REN hosts.txt hosts)
c) Finally, copy the newly renamed hosts file back to c:\windows\system32\drivers\etc, overwriting the old version.

Phew!

Step 4: Restart your browser

You might not need to do Step 4, but it won't hurt. Go for www.modelenginemaker.com, and it should come up with the new site!

Step 5: Remove the line from hosts after a few days

It would be wise to remove the new line from  your hosts file after a week or so; it will no longer be necessary (as your DNS server will now have the new address in it), and stray entries in the hosts file can cause all kinds of headaches when troubleshooting problems.

PS: Your hosts file can be a great way of foiling advertising and phishing websites; just set the hostname of the offending server to 127.0.0.1 (= local host, or your computer) and you'll never see it again. However, please be VERY careful, as you can really badly screw up your interweb experience with misuse of the hosts file.

Any questions, please ask in the discussion thread linked in the post above.  :ThumbsUp:

Cheers,
Ade
--
I'm just a poor old man. I have no time for law-breakers. My legs are grey. My ears are gnarled. My eyes are old and bent.

Offline AdeV

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PS
« Reply #2 on: February 01, 2013, 07:38:54 PM »
PS: If you are not comfortable doing the above... DON'T PANIC!  :help:

If you do nothing, you might have to wait up to 48 hours, but at some point your DNS record will "become stale", and automagically change to the new value. And MEM will be visible again.  :pinkelephant:
Cheers,
Ade
--
I'm just a poor old man. I have no time for law-breakers. My legs are grey. My ears are gnarled. My eyes are old and bent.