Thread: [Kindle] Very slow to transfer
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Old 12-10-2020, 06:44 PM   #20
davidfor
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Posts: 24,905
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Join Date: Jul 2011
Location: Sydney, Australia
Device: Kobo:Touch,Glo, AuraH2O, GloHD,AuraONE, ClaraHD, Libra H2O; tolinoepos
Quote:
Originally Posted by mst View Post
In my case, transferring files from Calibre to a device does take much longer than just copying the files from the HD to the device, even without sending and updating metadata. Sending 2k epubs from Calibre to the Kobo Clara HD takes about 10 hours. Copying them over with Fastcopy takes 15 minutes.

This is not a question of the speed of sending 2,000 1MB files vs. one file of 2GB. Something going on in the background between Calibre and the device is probably slowing down the transfer considerably. It also seems like sending smaller batches of hundreds of books takes less time than sending one large batch of thousands.

Has anybody additional ideas how to optimize this transfer process from Calibre to the device without using third-party tools like Fastcopy?
It has been a while since I sent that number of books to one of my Kobo device, but, it definitely didn't take that amount of time. And to check, I sent 100 books and it took less than 1 minute to send and another 12 seconds to update the metadata. I then tried the KoboTouchExtended driver and that took 1 minute 35 seconds for the send plus the same time for the metadata update. This included sending the covers to the device. These were fairly small book, but, it agrees with my experience. This was my Aura H2O that doesn't have many books on it. One of the ones with a lot of books would take longer for the metadata update, but, the actual book send wouldn't be much longer.

Calibre does do a lot of work when sending books to the device. It updates the metadata in the book before sending it. If needed, it does a conversion of the book to a format the device supports. For Kobo devices, you have the option to send the cover separately which means resizing the cover for three sizes and copying them. You should expect it to take longer than a simple copy, but, it shouldn't take that much longer.

If there is a problem, we need to see where it is. Run calibre in debug mode and get the debug logs. From that, you should be able to see where the time is being taken. Is it spread evenly over the actions? Or is there something taking a large chunk of time?
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