Atlassian’s issue tracker JIRA maintains file based indexes to make looking up issues faster. Certain changes (such as adding or changes custom fields) will make JIRA prompt administrators to rebuild these indexes.
Unfortunately, this process makes JIRA inaccessible until it is complete (up to 20 minutes for a medium sized instance on version 5, less on version 6). Version 6 added background re-indexing, however my experience of this is that it takes hours and uses up nearly all the CPU on the server.
This means that any well meaning user with the jira-administrators permission can take your JIRA offline or make it unusable by clicking the re-index button – no matter how many times you ask them not to! There is an issue in Atlassian’s tracker to make the feature only for JIRA system administrators, but it is likely a long way off.
In the meantime, here is how to hide the re-index button:
Add the following to the end of the Announcement Banner
#indexing-submit { display: none; }
This simply hides the button. If you do want to run a re-index, you can simply remove that style (or use something like Firebug to disable it).
Easy!