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This blog was co-authored by Sumit Lahiri


VMware vSphere 6.5 along with vSAN 6.5 now support 512e format. It is a feature that would allow customers to use large capacity drives with vSAN. This helps with density optimized vSAN clusters if the customer so chooses. 512e drives are only supported starting with VMFS6 and vSAN 6.5 and they are not supported with the previous VMFS or vSAN versions. Going forward, most of high capacity drives are likely to be Advance Format * (AF) drives according to drive vendors and OEMs.

The main difference between 512n & 512e is around sector sizes on the drive. 512e has physical sector size of 4k and it emulates 512 bytes’ sectors.

The disk sector size is an important factor in the design of an Operating System and Hypervisor (collectively called OS here) software such as device drivers and file systems, because it represents atomic unit of I/O operation on a disk drive. Not all OS versions have been modified to utilize 4KB sectors in the disk drives. Thus, the firmware of these newer devices may expose a logical sector size, which is either 4KB Native (4Kn) or 512B Emulation (512e).

The following table compares native 512-byte sectors to the new advanced formats:

table

512e drives are available in various capacities ranging from 300 GB to 10 TB. Following graph will provide glimpses of all the certified 512e drives and their capacities along with the suppliers’ details.

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Currently, about 230 plus different 512e drives from major drive vendors and OEMs like Seagate, WD, HGST, HPE, DELL, Lenovo, Fujitsu and Cisco are certified by VMware for vSAN 6.5 release. Following is the drive availability graph from various suppliers.

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Check VMware vCG to find certified 512e drives for vSAN 6.5 under “Build Your Own based on Certified Components”. Only the vCG listed 512e drives will be supported for vSAN.

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https://www.vmware.com/resources/compatibility/search.php?deviceCategory=vsan

There are many 512e based ready nodes with vSAN 6.5 are in pipeline. Please stay tuned and check VMware vCG for more details. Also, see following link for vSAN Hardware Quick Reference Guide

https://www.vmware.com/resources/compatibility/vsan_profile.html

See the following KB link from VMware to find more details.

https://kb.vmware.com/kb/2091600

References:

https://en.wikipedia.org/wiki/Advanced_Format