SMR drives and data integrity

[Moleyman]

HI everyone,

I have a concern over SMR drives and hope that someone else is able to offer any further insight.

For many years now I have been using 2TB, 3TB and 4TB drives to store my BluRay media on. I make ISO files which can range anywhere from 30GB to 50GB in size and these are then stored on my external "bare" drives (I use a SATA dock to copy the file over to the drive in question).

Now the software I use (Chronosync) to copy the files over to the bare storage drives compares the source file with the written file (using a checksum of some sort) to prove that the file has copied over correctly. Only a few times has Chronosync picked up the that source/destination file don't match - the bare hard drive didn't flag anything up during the copy process though so if I hadn't been using Chronosync I would have probably ended up with corrupt files.

So, this bring me to my actual question. It seems more and more drive are becoming SMR drives especially at the 4TB+ sizes.

As I understand it SMR drives will overlap the data written to the drive. So far, so good. But as you delete files and rewrite files to the SMR drive the SMR SMR drive will have to "move" some of the already written (and verified) data to another part of the drive.

So this means that the "moved" data has now not been verified and I am just resting on the luck of the drive controller/firmware to confirm the "moved" data is still correct. What worries me is that I know from first had experience that hard drives don't always get it right and report read/write errors - I gues this is how people start to get corrupt files to start with as the hard drive doesn't flag anything up when it should.

Or are SMR drives doing proper read/write verification on the moved data?

Thank you and enjoy the rest of your weekend.

Moley.

 

[Armageus]

"bare" drives in a sata dock aren't exactly ideal operating conditions for most hard drives (especially if it is one of those that has the drive vertical). Could be poor connection causing corruption.

Are you using ecc memory? If not then you can't guarantee that the data isn't being corrupted when read, before being written to the other drive.

Aside from a couple of early problems with SMR drives, I don't think there is inherently anything wrong with them given the correct use case.

 

[Moleyman]

Hi,

Thanks for the reply.

It is a "vertical" dock that I use, yes. I wasn't aware though that vertical operation was a bit of a no-no for hard drive though.

Also, I am using ECC memory (I use a 2008 MacPro tower that does actually use ECC RAM).

I haven't had that many times when the copied data doesn't verify; probably less than a dozen times over the years, but it was just enough to get me thinking about the SMR drives re-writing the data.

Thanks again for taking the time to reply.

MOley