Looking at Moodle support, documentation says:
System requirements

PHP must be 5.3.2 or later
Required PHP extensions: iconv, curl, ctype, zip, simplexml, spl, pcre, dom, xml, json
Required PHP memory_limit at least 40MB (64MB or more recommended if you have a choice)
Databases should be one of the following:
MySQL 5.0.25 or later (InnoDB storage engine highly recommended)
PostgreSQL 8.3 or later
Oracle 10.2 or later
MS SQL 2005 or later
Any standards-supporting browser from the past few years, for example:
Firefox 3 or later
Safari 3 or later
Google Chrome 4 or later
Opera 9 or later
MS Internet Explorer 7 or later
Note: The above system requirements are unchanged from Moodle 2.1.


When I log into my Moodle site, I am getting a message of:
Your Moodle files have been changed, and you are about to automatically upgrade your server to this version:

2.2.1 (Build: 20120109) (2011120501)

Once you do this you can not go back again.

Please note that this process can take a long time.

Are you sure you want to upgrade this server to this version?

Please advise me if it is OK to proceed. I can not afford to be without Moodle any more.

Thanks