I am making a RAID with three (and eventually four) 14 TB drives. What cluster size should I use when formatting the drives? I am a photographer, so I'm storing lots of photographs where the file size ranges from 60 MB to 999 MB. I'm on Windows - NFTS.

Here's the backstory. I originally had 2 drives in the RAID but I added a third drive. Let's call the 2 drives the J drive. The 3rd drive is an unallocated partition. The J drive is full of data and has a 4KB cluster size. If I format the unallocated partition also with 4KB, then my max size is limited. So I need to format the unallocated partition with 8KB or greater. I also need to convert the J drive to 8 KB or larger. So my first question is what cluster size should I use.

My second question is: given that the J drive is full of data, what is the best way to convert?

Can I:

  • format the unallocated partition (let's call this the I drive) with the tbd cluster size
  • copy all the files from J to I
  • format the J drive with the tbd cluster size
  • then extend volume I to include volume J

Will that work? And/or is there a more efficient way to accomplish this?

  • 1
    The cluster size of J is irrelevant and will be wiped by whatever cluster size I has. Formatting J is irrelevant when you basically write over it when extending the RAID, unless you are using some kind of software RAID that uses containers inside a filesystem that already exists on the drive. It might be good to describe your actual hardware/software setup.
    – Mokubai
    Jul 2 at 15:30
  • 1
    What RAID version are you using?
    – Mokubai
    Jul 2 at 15:32

Your posting is lacking crucial information to determine what is best for you - see the questions of Mokubai. Your posting lacks precision. You are defining the J partition but you are not introducing the I partition.

Regardless what configuration you use, any operation that requires modification of storage that already contains data is risky. Depending on the time span of such operations you would require constant mains supply to prevent interruption and loss of data.


Do not modify the hull (the partition) if there is data inside!

The safest way is to determine the needed available new size of your photo storage partition installed on your RAID setup taking into account the number of parity drives. You will then buy ALL those required drives, set them up in a RAID configuration and setup a new partition in there.

When operating only with pictures of 60MB and above the biggest available cluster size will be best to reduce the administrative overhead of your partition.

You format the partition and will copy the content of your old storage to the new storage.

Afterwards there is no need for the old drives anymore.

If your backup set (if it exists at all!) is working, you can use your two already existing old 14TB drives, one new 14TB drive, set up the RAID configuration and the partition (which would result in loosing all existing data in there). In your next step you would refill the bigger RAID drive from your hopefully working backup.

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