Hard disk drives encounter errors from time to time, so it’s a good thing that most have the ability to recover data anyway. But RAID systems usually have their own error recovery capabilities and can be thrown off when a hard disk pauses I/O. So it’s a good idea to use hard disk drives that allow you to disable or limit error recovery in RAID systems.
As I have done since version 3.5, I’m charting the storage changes in VMware’s latest release of vSphere, 5.1. Unlike version 5, which included many new technical storage features, 5.1 mainly tweaks existing features and adds these new elements to the mix.