When adding one or more larger disks to an existing RAID-DP traditional volume or aggregate, the disks are not utilized at full size.
Contrast this behavior with RAID-4 systems. When disks larger than the parity disk are added to a RAID-4 volume or aggregate, the first larger disk replaces and upsizes the parity disk. The original parity disk is then re-purposed as a data disk in the RAID group. Once the parity disk is upsized, new larger disk additions will be used up to the size of the new parity disk.
In the case of RAID-DP, the same behavior does not occur because the dual parity disk is still the original smaller size; the parity disk is not upsized to the larger disk size. As long as the dual parity disk is not upsized any larger disks added will continue to be used at the size of the dual parity disk.
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First of thanks a lot for your time and effort you took to read my questions and responded.
Though I am able to understand what you explained, however I am still searching for a exact point. My point (question) is, what does right size (down size) mean? What does Ontap do to match with old disk capacity. If you look at the two understanding (assumptions) I am holding and explained hose are:
Ontap format disk with a bigger block (byte) size and use entire disk? Or
A disk with larger capacity (1TB) formats to 600 GB in order to match it with low capacity disks which are already part of raid groups?
Will you be able explain above two points? Also I shall be higly grateful in case if you have any document or link to share with me for in depth understanding that I iwsh to have.