Write protecting my hard disk
I have a hard disk from an old Mac Pro that crashed. The drive was mounted as part of a RAID 0 array and at the time I assumed all the data was lost. Now I wonder if it was just the RAID controller that failed and I want to put the disk in a USB drive enclosure to see if I can read any of the data. But I’m concerned OS X may try to write something to the disk that will corrupt the RAID 0 structure. Can I can make my drive read-only? Mark Keegan I’m concerned that you are referring to your ‘drive’ as singular. RAID 0 distributes file data among two or more drives, as a way of speeding up data access. If you only have one drive from a two-drive RAID 0 set, then even if recover the data, you will only have the odd or even-numbered stripes from each file. Which effectively means you have nothing at all. For your plan to work, you will need to mount all the original drives in an enclosure that supports RAID 0. You can get these for about £70 on Amazon.
Once you have a suitable enclosure for the drives, you needn’t worry about write-protecting them. If the original problem was the RAID controller, you should be able to read them. If it wasn’t, you won’t. If you’re really determined, there are hardware write blockers for USB devices, from about £250. But, you can achieve the same thing perfectly well in software. Eject a disk in Finder and remount it in Terminal using But this won’t prevent OS X making changes to the drive, because by that point it’s already been mounted. That’s because the OS will automatically try and mount any drive in read-write mode as soon as it’s connected. What you need is something that intercepts OS X’s auto-mounting process and mounts the disk in read-only mode first. Disk Arbitrator is a free tool that does exactly this. You can download it from github.com/aburgh/Disk-Arbitrator.