I'm running 10.10.2 Beta. On purpose. And I'm using third party programs. However - I think the problem could be in Yosemite itself. Only the Nazi's on the Apple Developer forums can't get past the first line, so I can't get an intelligent response there Yosemite 10.10.2 Beta runs fine mostly so far. I love it. The thing I'm finding odd now though is that when I use either Carbon Copy Clone, or SuperDuper!, both programs report Read Errors. This has only begun to happen since coming up to 10.10.2 DiskUtility and fsck do not report any errors. Apple Support tell me that if those two programs don't find any errors on the disk, then there aren't any physical errors. Carbon Copy Clone tells me in it's popup, that Read Errors can also be caused by things OTHER THAN disk defects. Software, firmware etc. So I'm thinking a lag in the Read/Write buffers maybe? Something like that. It's a Mac Mini, OSX Yosemite. 10.10.2 Beta. Model Name: Mac mini Model Identifier: Macmini6,2 Processor Name: Intel Core i7 Processor Speed: 2.3 GHz Number of Processors: 1 Total Number of Cores: 4 L2 Cache (per Core):256 KB L3 Cache:6 MB Memory:16 GB Boot ROM Version:MM61.0106.B03 SMC Version (system):2.8f1 Now, Carbon Copy Clone went through and finished the Cloning of the drive. Reporting 21 Read errors. SuperDuper! stops when trying to read certain files in the log directory. Code: SuperDuper!: ***ERROR OCCURRED: SDCopy: Error copying /private/var/log/appfirewall.log to /Volumes/SuperDuper!/private/var/log/appfirewall.log of type 8 due to error 5: Input/output error If I exclude the whole log directory, it completes fine. Reading air writing with any other program from/to that directory does not cause errors. Just the Clone software. This is virtually a brand new system/drive, so I find it really unlikely that a drive is going to start failing when less than 12 months old. Possible, but improbable. My question is: Is anyone else showing similar errors with 10.10.2 Beta and cloning software. I have seen ONE person in the forums reported similar things, and they reverted to Mavericks, and the problem went away. I now can't find their post dam it. I don't want to revert anyway, I'd just like to pursue this idea that the R/W engine may be not absolutely stable in this release.