I have a 2009 MBP that I upgraded the HDD to a Seagate Momentus XT 750 back in 2012. Yesterday the machine was running crazy slow with a lot of beach balls so I rebooted to the Recovery HD and did a disk verify. Verify came back with disk corruption and a link error and so I did a Disk Repair. Since then everything seems fine. We're back to being snappy fast and in fact faster than it's been in a while. So now I'm wondering if the Seagate drive I installed last year is on it's way out. Any thoughts? Should I just replace the drive and carry on? Typically when I see this the hard drive continues to corrupt or be slow or lots of beach balling even after a repair so the signs to replace a drive are less obvious this time, hence my question. I wouldn't think a drive would corrupt for any reason unless it's dying... If anyone can suggest a good disk check tools (since seatools only runs on Windows or Dos) that would also be helpful. Before anyone says it, I have backups via TM and full backup. Thanks!