ASM - diskgroup with more than 2 LUNs, two rman operations slows down - restore database; and valida

Hi all,

last few days I was testing possible configurations of raid and asm. But I noticed some strange behaviour. When I create diskgroup with more than 2 LUNs, two rman operations

slows down - restore database; and validate database;

As you can see bellow with 5 LUNs these operations are more than two times slower. I have tested it with 19c and 18c. I noticed that on 5 LUNs it makes only 9367 disk reads

compared to 2 LUNs with 35657 disk reads. Could you explain me this behaviour. Is it bug or is it by design?

 

Database size - 34,3 GB

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2x raid 1 (2x SSD), external redundancy, 4MB ASM AU, 256K RAID stripe size