HP P2000 G3 iSCSI MSA Hard disk drives Fault

[AlexMn]

We have a storage HP P2000 G3 iSCSI MSA Dual Controller SFF.
There have been installed 24 hard drives model EG0146FARTR.
Created RAID 5 with 2 Spare, one logical drive.
At about 6 months, all worked fine.
At one point faulted two hard drives with error "Excessive media errors".
Out of the remaining 22 drives RAID 6 was created.
Then the other drives have become to fail.
Altogether 11 drives failures.
A request to HP was made to the replacement all 24 hard disk drives.
A response was received - This party is not are defective and will replace only the faulty hard drives.

We still have 13 hard drives.
The question is, what do we do with them?
How and wherewith is now test hard drives?

HDD

Model: HP EG0146FARTR

Revision: HPD5

Type: SAS

Size: 146.6 Gb