There are a few common symptoms of a hard drive that is starting to age with Linux installed. Of course you should use
SMART tools to keep an eye on your hard drive performance on a regular basis.
System freezing: while working on the server remotely, or while the server is under normal operation the operating system will freeze. This often requires a hard reboot and filesystem check before the system comes back online. Any hard freeze should be taken seriously and prompt a support ticket for hardware support.
Missing files/partitions: A secondary/tertiary hard drive may have bad sectors and in some cases an entire bad partition. This will result in only partial ability to read the files on the disk.
Undetected hard drive: A secondary/tertiary drive may stop showing up in the live system entirely. This happens in the most extreme cases and indicates that the IDE/SATA/SCSI controller can no longer read the disk. In this case there are few options for data recovery beyond shipping the drive to a clean-room operation where they can dissect the drive.
Hard drive noise: This of course cannot be diagnosed remotely, but if you suspect your hard drive is starting to fail you may open a ticket and have us inspect the hardware. On rented servers the hardware is owned by NanoServers and replaced free-of-charge upon failure.
If you suspect at any time that your hard drive is failing or about to fail you should open a support ticket via MyCP and notify us so our Support Team can assist you with diagnosis & recovery.