RAID 10 Capabilities
Is it possible to combine different disks in a RAID10?
Different capacities. It is not recommended to use disks with different capacities because the array capacity
will be limited by the size of the smallest disk leaving a part of the disk space on the larger disks unusable.
Different types. It is not recommended to use disks that differ by type and characteristics in a RAID10,
for example rotational hard drives and SSD, or rotational hard drives with different RPMs,
because the array performance will be limited by the slowest disk.
Different disk vendors and disks with different ages. It doesn't matter - you can create a RAID0 using disks from different vendors
and disks that differ by age.
If there is a RAID0 with data, is it possible to create RAID10 by just adding blank disks and don't lose the data.
Yes, it would require to take as many new disks as there are in the original RAID0, and just copy data to these new disks.
Most controllers can do this.
Can RAID10 replace the backup?
RAID10 cannot be considered as a backup replacement because the goal of backup is to eliminate single points of failure.
RAID10 array has a shared PSU, one for all disks. In addition, all the RAID10 member disks are located in one place and, for example,
in case of a fire all the disks would be burnt and all data would be lost.
Is it possible to take out one of the RAID10 member disks, connect it to a PC, and access the data?
No, because RAID10 layout utilizes striping technique where data blocks are written to the member disks in turn.
Usually block size is so small that a file with a typical size is stored on several member disks rather than on one disk.
So it is impossible to get data from a separate member disk except for some really small files which can be only extracted using raw recovery.
Is it possible to add disks to a RAID10?
In practice, no. The only option is to back up the array data, recreate the array (add disks), and then restore data from the backup.
Note that you can add only even number of disks.
If there are two 1TB disks in a RAID0 and one separate 2 TB disk, is it possible to create a RAID10 on these disks?
No, to create a RAID10 you need at least four disks.
In this particular case in addition to the 2TB disk you need another disk not less than 1 TB in size.
If using mdraid software in order not to lose space on the 2TB disk, it is recommended to create 1 TB partition first,
and then create the RAID10 array using this partition. In this case the rest 1TB of disk space can be used to store other data.
Otherwise, you lose 1TB of storage space.
However, there is one more option - RAID1E which allows to create layout resembling RAID10 using the odd number of disks.
Keep in mind that it is still desirable to have disks with the same sizes to use all the disk space.
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