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Help Nandriod Backup

usmann090

usmann090

Well-Known Member
I have read alot about nandriod backup.
And I also do make backup.
But recenlty I have read about md5 checksum.
I know it can verify that whether the backup copied from phone to pc is exactly same.
But I wanna know that if there was a problem/error during making backup with TWRP or CWM is there any way to detect that ?
Because I have suffered from that.My backup does not work and I have to flash stock.
 
Just checked TWRP for my device and you can turn it off for backups (creating the backup), but I'm not sure if that makes a difference to the restore.
 
El Presidente said:
I'm pretty sure you can turn md5 verification off.

What phone do you have? There may be another way of returning to stock if you need.
Click to expand...
My device in SM-N910H
I have make Backup and md5 was on TWRP.
But I wanna ask how can I know that the backup has no error in it ?
 
If you have another working backup somewhere just reflash the backup, if there is an error at least you can still revert to the old backup. Isn't that what the md5 check is for? Iv'e always selected to skip md5 check and I am sure, luckily (touch wood), I have never had a duff backup yet. I am not rooted at the moment so can't check, but isn't there somewhere to navigate in TWRP to verify backup or something?
 
SavageRobot said:
If you have another working backup somewhere just reflash the backup, if there is an error at least you can still revert to the old backup. Isn't that what the md5 check is for? Iv'e always selected to skip md5 check and I am sure, luckily (touch wood), I have never had a duff backup yet. I am not rooted at the moment so can't check, but isn't there somewhere to navigate in TWRP to verify backup or something?
Click to expand...
Yes there is option to navigate in twrp
But what I wanna know is that when the md5 is generated for my backup ; How would I know that the backup created is okay?
Because I make backup of my stock rom before flashing custom rom with md5 checked.
But flashing rom failed.
So I tried to restore my backup but unfortunately there was a problem in backup.
How could I know that the backup created is exactly perfect without any problem?
 
http://androidforums.com/threads/md5-verification.443074/

Lots of great options in there for verifying the MD5 sum of your files and backups on both your device and your PC.

In my File Verifier for Android app, there's a function for verifying the Nandroid backup (navigate to the backup directory folder, long-press the backup folder-name, and select Verify Nandroid Backup).

The app does assume that the backup folder is in a readable folder since this app does not use root (I can't remember if recent TWRP and/or CWM make their backups to a protected folder).

If you have trouble with that, you can probably use an Android Terminal Emulator app, navigate to the backup folder, and then type "md5sum -c <file>.md5" to ask the md5sum utility to check the MD5 digest of the file referenced in the <file>.md5 file against the MD5 digest listed/contained in that file.

Cheers!
 
usmann090 said:
Yes there is option to navigate in twrp
But what I wanna know is that when the md5 is generated for my backup ; How would I know that the backup created is okay?
Because I make backup of my stock rom before flashing custom rom with md5 checked.
But flashing rom failed.
So I tried to restore my backup but unfortunately there was a problem in backup.
How could I know that the backup created is exactly perfect without any problem?
Click to expand...

If I'm understanding your question correctly, the MD5 is not a qualifier to say the backup you just made is totally complete and perfect in every way such that it will work for you when you try it later.

The purpose of an MD5 for our use is more so to ensure there has been no tampering or data loss in a given file following a transfer of said file between two or more mediums.

So for example if you made a backup, you check the Md5 and write it down for future use. You then upload that file to a cloud server such as Dropbox, Mega, etc or maybe you even transfer the backup to the hard drive on your PC. Then at a later time, you need that file so you download it through the "series of tubes" :D within the internet or maybe you transfer it from the PC through the USB cable to the phone. After receiving the file, you check the MD5 to make sure that it matches, thereby ensuring that every byte in that file is exactly the same as when you created it. That's what the MD5 brings to the table: verification of exactness.

So if you did a backup and unbeknownst to you, it was a bad backup - maybe a partial backup or missing a key component(s), it would still generate an MD5. But knowing that MD5 doesn't change the fact it's a bad backup.

So how could you absolutely know if every single backup you make is good and will work when you try to restore? I'm not even sure that's possible to be honest. I've always just looked at the size and compared it to other backups on the same device. If they're close in size, it's probably good. If one backup is 120 MB and the rest are 3.5 GB, then you can pretty much say you have a bad one.
 
In the "early days" (LOL, 2010, when I wrote my AFV app), checking the MD5 of any ROM that you downloaded / transferred to your phone was important because lots of folks would get an error either installing (from custom recovery) or running the resulting flashed ROM if the download was incomplete/bad.

Same deal goes for a Nandroid backup--it's a great peace-of-mind to know that the MD5 sums that the backup calculated on the resulting files still match after you've transferred those file to somewhere else--and the Nandroid files are typically much larger than a custom ROM, so (IMO) there's a bigger/better chance for a dropped bit or two...

Memory, USB cables, and transfer methods do indeed seem to be much better nowadays, but I'd still sleep better knowing that I had a good, whole, uncorrupted copy of something :).
 
iowabowtech said:
If I'm understanding your question correctly, the MD5 is not a qualifier to say the backup you just made is totally complete and perfect in every way such that it will work for you when you try it later.

The purpose of an MD5 for our use is more so to ensure there has been no tampering or data loss in a given file following a transfer of said file between two or more mediums.

So for example if you made a backup, you check the Md5 and write it down for future use. You then upload that file to a cloud server such as Dropbox, Mega, etc or maybe you even transfer the backup to the hard drive on your PC. Then at a later time, you need that file so you download it through the "series of tubes" :D within the internet or maybe you transfer it from the PC through the USB cable to the phone. After receiving the file, you check the MD5 to make sure that it matches, thereby ensuring that every byte in that file is exactly the same as when you created it. That's what the MD5 brings to the table: verification of exactness.

So if you did a backup and unbeknownst to you, it was a bad backup - maybe a partial backup or missing a key component(s), it would still generate an MD5. But knowing that MD5 doesn't change the fact it's a bad backup.

So how could you absolutely know if every single backup you make is good and will work when you try to restore? I'm not even sure that's possible to be honest. I've always just looked at the size and compared it to other backups on the same device. If they're close in size, it's probably good. If one backup is 120 MB and the rest are 3.5 GB, then you can pretty much say you have a bad one.
Click to expand...
Yes this is exactly what I was asking for.
Thank you
 
scary alien said:
In the "early days" (LOL, 2010, when I wrote my AFV app), checking the MD5 of any ROM that you downloaded / transferred to your phone was important because lots of folks would get an error either installing (from custom recovery) or running the resulting flashed ROM if the download was incomplete/bad.

Same deal goes for a Nandroid backup--it's a great peace-of-mind to know that the MD5 sums that the backup calculated on the resulting files still match after you've transferred those file to somewhere else--and the Nandroid files are typically much larger than a custom ROM, so (IMO) there's a bigger/better chance for a dropped bit or two...

Memory, USB cables, and transfer methods do indeed seem to be much better nowadays, but I'd still sleep better knowing that I had a good, whole, uncorrupted copy of something :).
Click to expand...
Yes surely
 
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