Which unit, swapping drives

Newbie here, tia for any assistance.
I’ve created a few challenges for myself so trying to keep from digging a deeper hole.

  1. Which unit should be faster (all other things equal) a 5D(thunderbolt 2) with the ssd accelerator or a 5c?
    Both are connected directly to my iMac - the 5D using one of the Thunderbolt 3 ports and the 5C using one of the USB 3 ports.
    I am considering consolidating onto one of them and getting rid of the second. The 5D being older…

  2. Can I swap a very large drive for a smaller one that is not being used? I have a 8TB drive in a pack where all others are 4, so the unit states that 3+TB are “reserved for expansion.” I don’t want to upgrade to all 8s, so wondering if I can replace it with another 4 and use the 8 for something else.

Thanks again in advance.


Hi AP,
Just some comments from your questions assuming both are of equal ‘wear and tear’.

  1. the fastest between a 5C and a 5D will be the one with the faster RPM HDDs in (ie all 7200 RPM rather than 5400 RPM). The port connection is inconsequential if you have HDDs, as their read/write speed of HDDs is slower than the connection speed of both USB 3.0/3.1 or Thunderbolt 2/3. The only future benefit to keep in mind is if you want to daisy-chain another Thunderbolt-connected drive or monitor, in which case maintaining the thunderbolt connect has a benefit. The mSATA accelerator is useful if you access a number of files regularly, as they will be cached on the mSATA and read much faster.

  2. With any adjustments to RAID stacks, please have a separate backup made before you attempt anything. Yes, assuming your total stored data will not be >84% of the final data capacity of the HDD-rack AFTER you down-spec the HDD rack by removing an 8TB for a 4TB, it should be OK.
    Use the Drobo capacity calculator to check beforehand: