"HashCheck Error": A bad drive or a bad disk

[happyripping2025]

Hi,

Recently, I'm using makemkv to rip about 80-100 disc. Most of them finish successfully, but couple of them (~10) fail. I'm aware it may have something to do to the dirt on the disc and sometimes cleaning the disc brought the ripping success without any errors.

That said, I'm reading the information on the linked page in the log (http://www.makemkv.com/errors/hashcheck/), and it explicitly says:

Hash check error essentially means that the drive was unable to read the file from the disc, and what more, instead of raising the read error it silently returned corrupted data. Getting this error usually means a failing Blu-ray drive.

So with "hash check failed" errors (on multiple discs), does it suggest the drive may have intermittent failures and is worth a replacement? If I understand the quote message above correctly, the drive may also serve bad data silently when I insert a Windows installation disc or other data disc? That seems very problematic.

Using LibreDrive mode (v06.3 id=...)
Backing up disc into folder "Z:/Video/backup/ALIEN3_WW"
Processing BD+ code, please be patient - this may take up to few minutes
Processing BD+ code using generic SVQ from builtin/generic.svq
BD+ code processed, got 1 FUT(s) for 20 clip(s)
Loaded content hash table, will verify integrity of M2TS files.
Hash check failed for file 00701.m2ts at offset 77260800, file is corrupt.
Hash check failed for file 00701.m2ts at offset 80996352, file is corrupt.
Hash check failed for file 00701.m2ts at offset 84535296, file is corrupt.
Hash check failed for file 00701.m2ts at offset 85125120, file is corrupt.
Hash check failed for file 00701.m2ts at offset 85911552, file is corrupt.
Too many hash check errors in file 00701.m2ts.
Hash check for /BDMV/STREAM/00701.m2ts : 0.57% corrupt, 99.38% correct, 99.96% checked.
Hash check failed for file 00775.m2ts at offset 1387063296, file is corrupt.
Hash check failed for file 00775.m2ts at offset 1387259904, file is corrupt.
Hash check failed for file 00775.m2ts at offset 1390995456, file is corrupt.
Hash check failed for file 00775.m2ts at offset 1401415680, file is corrupt.
Hash check failed for file 00775.m2ts at offset 1407707136, file is corrupt.
Too many hash check errors in file 00775.m2ts.
Hash check for /BDMV/STREAM/00775.m2ts : 0.06% corrupt, 99.93% correct, 99.99% checked.
Encountered 21 errors of type 'HashCheck Error' - see http://www.makemkv.com/errors/hashcheck/...
Backup done but 2 files failed hash check

[dcoke22]

So with "hash check failed" errors (on multiple discs), does it suggest the drive may have intermittent failures and is worth a replacement? If I understand the quote message above correctly, the drive may also serve bad data silently when I insert a Windows installation disc or other data disc? That seems very problematic.

LG calls this feature 'Jamless Play':

Jamless Play Smooths Out Playback of Damaged Blu-ray or DVD Discs

The drive is essentially returning garbage data when it can't properly read a disc. I don't recall if that 'feature' can be turned off or not.

It is my understanding that Pioneer drives don't do this.

MakeMKV can detect this because blu-rays and 4K UHDs have something called the Content Hash Table, which is hashes of all the data on the disc. MakeMKV reads the disc, calculates the hash and compares it to the Content Hash Table stored on the disc. If they match, then the data read was correct. If they don't match, MakeMKV tries the read again until it either gets a good read or the retry limit is reached.

In the case of small percentage of discs ending up with hash check errors, it is probably the discs and not the drive. If most discs end up with hash check errors, then it might be the drive (unless all your discs are trashed for some reason).

In my experience, some drives just don't like some discs. Sometimes the same disc in a different drive will produce different results. This is why I have multiple different drives. Almost always I can get a good rip out of one of my drives, especially after gently cleaning the disc.

[happyripping2025]

Thanks for the information. That makes sense.

That said, in order to avoid confusion, I recommend updating the explanation at http://www.makemkv.com/errors/hashcheck/ to call out the possibility of some feature like "jamless play". The wording and reasoning there currently sounds very affirmative that hashcheck error should be considered a bad behavior of drive.

Hash check error essentially means that the drive was unable to read the file from the disc, and what more, instead of raising the read error it silently returned corrupted data. Getting this error usually means a failing Blu-ray drive.