Drupal cron job is really easy to setup. However for some old running websites cron job stops working after updating drupal to new version. For one of my websites I had similar issue. The cron job was not running. Neither automatically not manually. Running cron job used to return a blank white page, which means you dont know what the issue is. I even tried installing poormanscron module still it used to fail.
One of my drupal websites suddenly went into lot of issues 1) It became extremely slow and I had not done any changes to the website, and all my modules and scripts were upto date 2) It became inaccessible and was throwing 500 Internal server error and max database connection error.
Drupal can scale if you have the right server architecture. There are numerous large sites such as the economist.com that use Drupal. When you find performance issues on your website, its not one magic stick that will work. First check some modules to start debugging the issue:
An active drupal 7 website, one fine day was throwing the following error PDOException: SQLSTATE  User ******** already has more than 'max_user_connections' active connections in lock_may_be_available() (line 167 of ******************/includes/lock.inc). There were no changes done on the website nor to my webhosting so it was quite surprizing to suddenly see this error. However my website was not down. It was still working, Every time I get the error I would use refresh button in my browser and the page would appear correctly. However I did the following
One of my clients has a very simple website. Using Articles, Gallery, Views module and some utility modules. The website was running for a year on 7.14 and recently I upgraded it to 7.24. Upgrade from 7.14 to 7.24 went almost fine and website and theme was working fine.
Some pages I was getting a white empty screen like on Admin >> Status report. However I did not care that that , I thought it must be an issue with my browser cache.
Today I had a weird problem with one of my drupal websites. I did not make any changes to this website and it has been running for some years. Suddenly my theme is completely broken and its not appearing either on website or admin pages
On one of my websites, I had this weird issue one day suddenly . Both users and admin was not able to login to website. It was going into redirect Loop and it used to display page not found "404" or it used to just be on the login page. I read in forums on drupal.org and several other pages. There were many solutions proposed, which were actually quite confusing and not convincing I had not changed anything on my website to cause this issue, they why suddenly no-one is able to login.
I recently upgraded one of my site from Drupal 5 to Drupal 6 and found that the books and book pages were lost. I saw in Admin >> Content section that the content was there only the structure was lost.
Upon manually trying to recreate the books I was getting Duplicate error, so even the manual option was not working. It seems that this was a common error for many people
I did some reading and found many people have done some complex things to get around it. Let me tell you what worked for me.