One of the disk drives in my ReadyNAS Pro Business running OS6.9.3 started reporting “Detected high uncorrectable error count: [##] on disk 1”. I bought a new drive. A few weeks later it also reported “Detected increasing pending sector: count [##] on disk 1”. When the reported uncorrectable error count exceeded 50 errors I hot swapped in the new drive. My NAS recognized the new drive and quickly started resyncing the Volume data. A couple of hours later the NAS reported “Volume data health changed from Degraded to Redundant.” and “Disk in channel 1 (Internal) changed state from RESYNC to ONLINE.” I’m thinking life is good. But the next morning I see this, “Detected high pending sector count: [270] on disk 1 (Internal) [ST3500320NS, ########] after 13 power-on hours.” But this is the new drive. In preparation for disposal of the original drive I had reformatted the drive and scrubbed if with zeroes. With the new drive having 270 errors in twelve hours I felt that replacing the now new drive with the old drive was my best short term option. Another hot swap and a couple of hours later all is good again with the NAS. (I’ve ordered another replacement drive.) After this long introduction here is my question. After a week of operation with the original drive back in the NAS I haven’t seen any errors of any kind. What could have caused my original drive to report all those failures but now seems to work fine and what could have been wrong with the new out of the box replacement drive to generate all those errors?
Pending sectors (like reallocated sectors) are reported by the drive firmware itself. I don't know of anything the system can do to create either error.
Your scrubbing exercise might have resulted in the drive sparing the bad sectors. But I'd definitely schedule the built-in disk test in the NAS fairly frequently, and periodically look at the SMART stats (download the log zip, and look in smart_history.log and disk_info.log). The NAS email alerts use quite high thresholds (in my opinion much too high). So you need to keep on eye on the disk health yourself.
As far as the new drive goes, I have sometimes purchased drives that failed shortly after power-on. In some cases I suspect they were damaged in shipping/handling somewhere along the line.
What is the best way to run a S.M.A.R.T. test on the original drive? Is there a way to test the disk using RAIDar from the Admin page? Seagate has a tool call "SeaTools for Windows". Will that work or do I need a different tool or a Seagate legacy tool because the disk is older? I plan to connect the original drive to my Laptop using a USB cable from a SATA to USB adapter. Will that require using a program like Ext2Fsd so as to recognize the drive? Thanks for the help. Just odd that the drive is now reporting that is just fine.
You can use seatools even though Windows won't recognize the file system on the disk. It will still detect the disk, and let you select it for testing. You won't need ext2fsd or similar packages. This is also the case with Western Digital's lifeguard program.
Start with the short diagnostic test, and if that passes try using the long test.
