Can I mix these drives in my Synology 920+?

Will 5900RPM drives play nicely with 7200RPM drives, or will something go boom? I've got a 920+ with 4x 4TB 5900 drives running SHR1. I'm going to need to expand my storage soon, and I already know I don't want a DX drive (I'm not comfortable with losing another whole drive for parity if I create another volume, nor am I comfortable with a single volume reliant on a single sata cable, though feel free to try and change my mind on that point). My options are a) buy larger drives and swap them in for 2 or more of my existing drives, or b) buy a second box and more drives and manage them in a network. Right now, option b is a bit more costly than I want to go, and I was hoping to swap in 2x 8TB drives now followed by 2 more later in the year, or maybe buying a 2-bay box for the spare 4TB drives. After having read up on this, it looks like 8TB drives only come in 7200RPM flavour, and it's not advisable to mix RPMs. I have two questions on this. 1) Is it possible to mix the two RPMs, and if so, is it viable for medium term (i.e. could any potential faults/damage accumulate over the next 6-12 months or so?). 2) With SHR, will either of the 2x 8TB drives actually offer their full 8TB of space if mixed with 2x 4TB drives? Thanks to all for any help you can give. Cheers!

AN Anothernasuser asked on 23 January 2021, 16:17
1 answers / 135 views / 0 votes
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If you replace two 4TB drives with two 8TB drives, you will only gain 4TB of extra storage space https://www.synology.com/en-uk/support/RAID_calculator?hdds=4%20TB|4%20TB|8%20TB|8%20TB


If you get an expansion unit, you will get extra 8TB. Yes, it is a seperate volume and RAID connected via eSATA. But you gain more space. And even if cable breaks, your RAID will not get damaged. DSM is smart enoguh to detect this.


Surely it is not great to power on an extra unit and considering another NAS would make sense. But in this case I would rather geta 6 bay model or bigger. Slide all those drives in there and have couple of bays free for the future upgrade.


I hope this helps.