My Reolink 8Ch NVR has:

1 x internal 4TB HDD
1 x external 4TB HDD (eSATA)

I am using the Mac desktop app to monitor usage of these drives and have noticed that after initialising both drives, they showed 3179 GB

The external drive was automatically taken into use, indicated by a steady reduction in available disk space.

I anticipated that once the external drive was empty the operating system would automatically switch to the internal drive.

However, when the external drive reached 2816.77 the operating system switched to the internal drive which is now steadily reducing in disk space.

Current readings:

Internal 0 3179 GB 3106.77
External eSATA 3179 GB 2816.77


Questions:

1. As these are 4TB drives, why is there only 3179 GB available after initialisation?

2. How does the operating system deploy available disk space across multiple drives?

I live in the UK and have a Reolink NVR and 8 x 4k cameras.
I have been thinking of getting a wi-fi camera and would love to receive Argus 2E for test, evaluation and review

This file is not intended for windows users
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I can tell you that in the past I have tried exporting Mac spreadsheets to Excel format and embedded formulas haven't worked properly afterwards.
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Please don't keep on at me... I'm sharing the file as is and that's it!

From a personal point of view, this spreadsheet has now served it purpose and I have no further use for it.
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Feel free to convert it - no point in me trying as I am a Mac user and have no way of testing it

First, convert it, for those of us that use excel. -> https://cloudconvert.com/numbers-to-xls
Second, upload it, -> https://gofile.io/?t=uploadFiles
Third, share download link -> https://gofile.io/?c=ikR6ii

Fourth, Crack on mate - fill your boots!

... and screenhots 6-10
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step10.jpg

Apologies to anyone who has been waiting to download the spreadsheet.
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The spreadsheet cannot be uploaded to the forum because it is in Mac format (.numbers)
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Where there's a will, there's a way!
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Here is a workaround...
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I have appended .jpg to the end of the filename to 'fool' the system.
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You can now download the spreadsheet but you will need to remove the .jpg before opening it.
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Some users may not be familiar with this process, so I have prepared a series of 10 screenshots.
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Hope this helps - enjoy!
Reolink-NVR-HDD-Monitor-V1.0.numbers.jpg
step1.jpg
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Thanks for everything Slicker55

You're very welcome...

Interested to hear what kit you have, check my system out, with those two HDD's you have just installed you will get 17 days 24/7 recording using 8 cameras (that's 7 x 8MP and 1 x 5MP)

The spreadsheet will be handy if you have a Mac computer/laptop with 'Numbers' installed.

They (Reolink) say they're working on uploading the spreadsheet - some issues because it is in Mac format

Happy to send it to you directly if you provide an email address

...also, you may be interested one of my other posts...
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The spreadsheet has been uploaded - waiting for admin to make it available for viewing and download.

@Splen Dence
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Here you go mate...
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I managed to speak to StarTech.com via online chat.
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Here's the transcript:
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[06/04/2020, 22:42:55] Hi, I am talking to someone on a CCTV forum and I have recommended your e-SATA enclosure (S351BMU33ETG)... note, I am based in the UK... he says he has found a similar item on amazon.COM S351BMU33ET (Note G is missing). Is this the same enclosure ... maybe the G defines models for export?
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[06/04/2020, 22:44:33] Monica: One moment while I look into that for you.
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[06/04/2020, 22:46:34] Monica: Thank you for your patience. The S351BMU33ET from Amazon.com is the NA version of the unit which does not include UK/EU power adapter and the S351BMU33ETG includes universal power adapter for NA/EU/UK/ANZ

Thanks for the info, I found the Enclosure, S351BMU33ETG but instead I dropped the "g" S351BMU33ET on Amazon.com and found the same one for 1/2 the price.

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A good find ... nice solid piece of kit
I don't know what the difference is between the two models (if any), suggest you cross-check specification
I am in the UK...
The page for S351BMU33ET comes up on amazon.co.uk but is no longer available over here.