Pan E100H - a method for reconnecting drives without Formatting - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 2 Old 05-16-2019, 07:41 PM - Thread Starter
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Pan E100H - a method for reconnecting drives without Formatting

Usually if you swap the original drive with recordings on it, for a new drive, the recorder makes you format the new drive before you can make any new recordings.



Then if you attempt to swap the original drive back in, the recorder does not recognize it and forces you to format the original drive. It also does not recognize the old recordings you know still exist on that drive.

This is a method to do that:

it does not involve yanking molex power connectors

Simply its been discovered the first few sectors of the drive has a type of transaction log. Its unique and incremented as changes are made to the number and condition of the recordings on the current drive.

If you backup the first few sectors of the current drive and restore those to the first few sectors of the drive you want to restore to the recorder. Then the restored drive will be recognized and any existing recordings on the drive will be presented for playback.

If you have lost a current drives transaction log, for example if the drive ceases to work, but you still have an old drive with recordings on it, you should be able to create a new transaction log on a fresh blank drive and back that up. Then restore that transaction log to the older drive with recordings on it.

It is unknown at this time whether drives with recordings can be swapped between two recorders of the same model, or within the same family of recorders. I do not have enough duplicate gear, or samples of gear from the same family to answer those questions. This has only been tested with multiple drives on the same recorder.

I do know things changed a bit beginning with the DMR-EH55, EH75V at that time (I believe) the introduction of TVGOS may have added additional firmware to the drive image (so) this method may be adaptable.
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post #2 of 2 Old 05-18-2019, 07:24 PM - Thread Starter
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update:

I've had a bit more experience with this method and it continues to work.

IsoBuster has also been found to be all that you need to perform this trick. Peter informed me the "Extract and Clone" features could be used to [both] Backup and Restore a few consecutive sectors from the beginning of one drive to a different drive.

I tried it and it worked.

Basically IsoBuster "Extract" can target specific raw sectors from a currently attached disk. Those can be Backed up to a file. Then the target disk can be attached and the Backup file used like a disk image to bring it into IsoBusters focus and the "Clone" feature used to merge the "virtual" Backup disk with the target Restoration disk. During Clone it asks to (where?) and you can pick the target Restoration disk.

Since the Backup is only a few bytes, when the Clone function runs out of Sectors it leaves the rest of the Sectors of the Restoration disk alone.. and completes the transaction log restore.

Its a "giddy" unreal feeling to see this actually work.. since its frustrated me for so long.

I've had quite a day or night where I assumed the Title list on the drive was merely a fake and never actually read.. and that only the "nvram memory" copy really mattered.. that is (wrong) .. I am so glad to be wrong.

I would caution however you need to be careful and make full disk image or physical hdd backups until you feel confident using this technique.

Also you need the specific number of Sectors to Backup and Restore.

My first attempts were Educated "guesses" and while not exactly... a face-pancake into the pavement... I did wrongly overshoot and got a weird result.

I overwrote the IFO section of the target drive and got "ghost" entries with no Titles, but accurate Assigned Recording numbers and Date and Times with no Meta data.... yeah that is as weird as it sounds.

The solution was IsoBuster again.. IsoBuster understands the actual structure of the disk and makes it trivial to ask "what Sector is that" by right clicking an icon for various things. Then IsoBuster makes it easy to Extract all the Sectors from two different locations to back them up to a file.. and finally Clone lets you put them back on a different drive.

I've tried cobbling together lots of other tools and scripts.. but I always end up "Wasting my time".. I should have just asked Peter to start with.. "does IsoBuster already do this ..?"

---

So its also possible to end up with Multiple drives you can swap back and forth.. (until) you actually make a change on one drive that updates the transaction log.

Those events seem to be related to (format)(delete title)(update title) and so on.. basically anything that requires writing a change to the hard disk.

---

This technique while created to deal with using multiple HDDs and swapping them out like large VHS tapes.. and wanting to swap them back in for playback.. can also be used in a different way.

Its been known for some time that after the EH55 models Panasonic recorders had to have a factory prepped hard drive, or you needed a "correct" firmware update disk in order to replace a failed HDD.

The same Backup and Restore method can be used before the HDD fails to backup a factory prep "Rescue" header.

It will have a transact-log that is out of date.. but once the factory firmware has been verified.. it will simply request permission to reformat the drive to give it a fresh transact-log (sort of like a fresh coat of paint) and new recordings can then be created.

I don't know how compatible they would be between recorders.. but there are a couple of solid advantages to doing it this way...

1. If you can't find the correct firmware update to download, and method to burn the media to a FW update disk. Or Panasonic decides to stop making the FW available.

2. If the DVD reader/burner drive has "died" and can no longer be used to read the FW update disk

Previously, before understanding the transact-log nature of the HDD there were even rumors that you had to tweak the FW or somehow downgrade then upgrade the FW because it could only be used "once" before it could not be used again.. I think it might be because FW update looked at the transact log and only allowed "roll-forward" not backwards.. in a weird catch-22 situation.

Last edited by jwillis84; 05-18-2019 at 08:13 PM.
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