I had a 4TB drive fail a while back so I replaced it with a new 8TB drive.  The data rebuild seemed to go fine and everything was back to normal.  It wasn't until several days later that I noticed that the new drive only contained a few hundred GB of data when it originally contained about 3TB.  I don't know what happened, but apparently whatever data was written to the drive simply disappeared.  It was all media files that were replaceable so it wasn't a disaster.  It was just a strange occurrence that I had never seen before.  I've been running unRAID for about 10 years now and I try to keep it up to date.  This happened about 4 or 5 months ago so I was using an older version of unRAID 6.  I'm currently running unRAID Pro version 6.6.5 with dual parity drives, 28 data drives, a 1TB SSD cache drive and a current capacity of 130TB with 45.4TB free.

 

On another note, it seems like unRAID likes to report drive failures more frequently than before.  I've replaced at least a couple of "failed" drives over the past several months.  I always buy extra drives when I see them on sale and do a preclear so they're ready to go in case of a drive failure.  The thing is, I've run complete diagnostics on the "failed" drives using either WD Data Lifeguard or SeaTools and they've all passed with flying colors.  I then do a full erase and run another preclear to use them as a replacement drive.  I don't know if it's just a glitch in the system or if unRAID is overly sensitive to reporting drive failures, but so far every drive that has been reported as failed in the array lately has tested fine.  None of them reported S.M.A.R.T. failures at any time.  If I see a S.M.A.R.T. failure I know the drive is toast and just trash it.

Did your format the drive before, during or after the rebuild?

 

8 minutes ago, captain_video said:

On another note, it seems like unRAID likes to report drive failures more frequently than before.

Most "failed" drives are cable/connection issues, if you want next time pos time post the diagnostics so you can get some advice.

1 hour ago, johnnie.black said:

Did your format the drive before, during or after the rebuild?

 

Most "failed" drives are cable/connection issues, if you want next time pos time post the diagnostics so you can get some advice.

I didn't format the drive at all.  The only thing I do to a new drive is perform a preclear running in the background so it's ready to install when needed.  The drive was installed in the array as a blank precleared drive and then the data was rebuilt from parity.  The drive gets formatted on the fly as part of the data rebuild.  All of my drives were migrated from ReiserFS to XFS quite some time ago.

 

Anytime I start to see a drive look like it's about to fail I always shut down the array and check my connections.  I pull the drive and reseat it in the backplane and then check the cable connection between the backplane and the controller card.  I also pull the card and reseat it in the PCI-e slot.

4 minutes ago, captain_video said:

I didn't format the drive at all.

Then we'd need the diags from the replacement to maybe see what happened, it's obviously not normal.

Unfortunately, that ship has sailed.  This happened several months ago and I've been gradually replacing the missing data as I discover what got deleted.  It was a one-time thing so I'm not all that concerned about it.  It was mostly annoying and a bit of a surprise when I discovered what had happened.