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ONTAP Discussions

lun block size

Ashun
3,208 Views

I have a question,
This KB mentions: The default disk block size for WAFL is 4k, which is equal to LUN's physical block size
But when I use lun show-fields block-size, I get a different result. Am I wrong?

KB:

Which command is used to display the physical block size of LUN? - NetApp Knowledge Base

 

Ashun_1-1737096558253.png

 

1 ACCEPTED SOLUTION

chamfer
3,080 Views

Hi @Ashun ,

 

  • Traditional block size advertised by hard disks is 512 bytes.
  • NetApp LUNs use a larger block size to store data while continuing to advertise smaller 512 byte blocks to the host for compatibility purposes.
  • Advertised blocks are referred to as logical blocks and underlying storage block is referred to as a physical block.
  • NetApp LUN stores data in 4 KB physical blocks, which yields eight 512 byte logical blocks per physical block.

 

Reference: https://kb.netapp.com/on-prem/ontap/da/SAN/SAN-KBs/How_to_identify_unaligned_IO_on_LUNs

 

 

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1 REPLY 1

chamfer
3,081 Views

Hi @Ashun ,

 

  • Traditional block size advertised by hard disks is 512 bytes.
  • NetApp LUNs use a larger block size to store data while continuing to advertise smaller 512 byte blocks to the host for compatibility purposes.
  • Advertised blocks are referred to as logical blocks and underlying storage block is referred to as a physical block.
  • NetApp LUN stores data in 4 KB physical blocks, which yields eight 512 byte logical blocks per physical block.

 

Reference: https://kb.netapp.com/on-prem/ontap/da/SAN/SAN-KBs/How_to_identify_unaligned_IO_on_LUNs

 

 

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