Solved Macrium Auto-Verify and Manual verify speed differences

wiganken · Jul 8, 2023

Verify speed is very slow when done manually after creation.
I timed the verification of a 60GB image and found the following: -
If the image is auto-verified immediately after creation then it takes about 20 seconds.
Manually verifying the same image after creation took around 8 minutes.

This is 24x longer. Does anyone else find this? If so then can anyone say why this happens?

DigitalGoat · Jul 8, 2023

It could be that auto verify is verifying a copy of the data in cache, so RAM being much quicker to read from, whereas manual verifies using the data on disk, just a guess.

wiganken · Jul 8, 2023

@DigitalGoat - Thanks. I should have made it clear that the images are stored on a USB3.1 Gen 1 connected external SSD.

Yes, I can see that the USB3.1 Gen 1 may be a bottleneck at 5 Gbps transfer speed compared with data cache stored in RAM but would it be 24x slower?

Wisewiz · Jul 29, 2023

@wiganken

Have you found a resolution to this problem? I have compared speeds for about ten full image backups (OS and all programs -- two drives on one NVMe PCIe) and found the speeds strictly comparable: no significant difference here.

Fabler2 · Jul 29, 2023

wiganken said:
Verify speed is very slow when done manually after creation.
I timed the verification of a 60GB image and found the following: -
If the image is auto-verified immediately after creation then it takes about 20 seconds.
Manually verifying the same image after creation took around 8 minutes.

This is 24x longer. Does anyone else find this? If so then can anyone say why this happens?

I found that the same thing happens on Aeomi Backupper.

Wisewiz · Jul 29, 2023

I think at least for large images, DigitalGoat is right. The source of the database is different for the two methods.

EDIT: Sorry. Just realized that was bloody obvious. Not awake yet, I guess.

wiganken · Jul 29, 2023

Wisewiz said:
Have you found a resolution to this problem?

@Wisewiz - Not as such but I tried it again on a smaller image and the difference was not as much: -
An 11GB image Auto-verify after creation took about 20 seconds. Manually verifying the same image (on the USB 3.1 Gen1 connected SSD) next day took about 1 minute so only 3x longer. These are approximate figures from memory since I didn't write down the exact times but I remember thinking "3x instead of 24x? Why such a difference"? Still no definite answer. Maybe something else was slowing down the verify process the first time. Just guessing.

My next backup is due on 1st August so I'll check again and report back with actual numbers. Watch this space.

Wisewiz · Jul 29, 2023

Just wondering: Have you considered doing File and Folder backups for your data (perhaps in chunks of not-too-large sizes) and restricting your Imaging operations to the disks/drives with your OS/OSs on it/them? Back (in the day, before retirement) when I had large data collections, I split them up into manageable chunks for backups, and just imaged my OS drive. Took very little time for each separate operation, so I could do them more often, and didn't have to do them all at once..

wiganken · Jul 30, 2023

The method I use is to do a 'Full' backup of all partitions once every 3 months. In-between these I do 'Diff' backups every 2 weeks. In my case I feel it is often enough for the amount of changes I make. Of course the 'Diff' image size grows starting at 3GB, 11Gb etc. until the 'Diff' image size becomes large enough for me to consider creating a new 'Full' image and starting again.
I have just done a manual verify on that same 11GB image and it took 2m 03s timed using my phone's stop watch.
The day after tomorrow (1st August) is the scheduled 'Diff' backup so I will time the auto-verify and later on I will manually verify the same image for comparison.

wiganken · Aug 1, 2023

@Wisewiz - As promised here is my final report to conclude this thread: -
Today's Differential image was 13.19GB size and the auto-verify part took 39 secs. I switched off the computer and restarted it to clear out any cache. I then ran a manual verify on the same image and it took 2 min 21 secs. This is 3.6x longer than the auto verify time confirming what I said in post #7. At least I know what to expect now. I think the 24x longer instance was non-typical. I hope.

It's no big deal but it's good to put this to bed and move on.

Solved Macrium Auto-Verify and Manual verify speed differences

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