Seagate Ironwolf Pro with 2 different models in the same RAID5

English Storage
1

We’ve a TS-853A which had 4 Seagate Ironwolf pro (ST4000NE001) HDDs in it. One of them failed and I tried replacing it with another ironwolf pro with the same capacity(4TB) but another model(ST4000NT001).

Is it normal that there may be capacity differences between different models of the same brand, or is there something I should have done before pluging-in the new drive?
The fdisk -l output for the drives:
One of the old drives(ST4000NE001):
Disk /dev/sdb: 4000.7 GB, 4000787030016 bytes
Disk /dev/sdb1: 542 MB, 542848000 bytes
Disk /dev/sdb2: 542 MB, 542865408 bytes
Disk /dev/sdb3: 3999.1 GB, 3999180485632 bytes
Disk /dev/sdb4: 509 MB, 509964288 bytes

The “fdisk -l” ourputs of the new drive(ST4000NT001):
Disk /dev/sda: 4000.7 GB, 4000787030016 bytes
Disk /dev/sda1: 542 MB, 542848000 bytes
Disk /dev/sda2: 542 MB, 542865408 bytes
Disk /dev/sda3: 3998.6 GB, 3998637617152 bytes
Disk /dev/sda4: 551 MB, 551089664 bytes

Best regards,

Eren

2

The actual data partition is the same…just differences in swap

3

Thank you @dolbyman for your answer.

If my calculations are correct, there is approximately 517MB difference between sda3 and sdb3. sda3(new hdd) is 517MB smaller than sdb3.
Disk /dev/sdb3: 3999.1 GB, 3999180485632 bytes
Disk /dev/sda3: 3998.6 GB, 3998637617152 bytes
Is this normal? The HDDs are both Ironwolf pro, but have different model numbers.

Also, will I be able to use the new HDD in the RAID configuration without breaking anything?

The new HDD seems healthy:

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image801×378 32.6 KB

But, I cannot rebuild the RAID or create a new volume because, the the new HHD does not get listed on the relevant pages:

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image594×526 13.2 KB

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image882×387 23.1 KB

4

the fresh disk should have been swapped into the degraded RAID (when the busted disk is ejected) automatically, no user interaction would be required

5

I guess something went wrong when I first inserted the new drive as the HDD got partioned wrongly. I had to clear the HDD with

dd if=/dev/zero of=/dev/sda bs=512 count=1

and rebooted the qnap. After that the raid began rebuilding itself automatically.