VMware Cloud Community
mmurrin
Contributor
Contributor

RAW mapping block size question

For our file servers, I plan on doing raw device mapping, but I have a question about the block size for the vm luns. The raw luns are going to be around 400-600GB each. Does raw device mapping effect the block size of the vm lun? The file server vm will be in a 200 GB lun, so I have the block size set to 1MB right now.

Tags (1)
Reply
0 Kudos
2 Replies
kjb007
Immortal
Immortal

RDM's do not have the block size restriction, as do VMFS datastores. If the file server was going to be a vmdk on a vmfs datastore, the your vmfs would have had to be 2 MB for a max of 512 GB disk size, and 4 MB for a max of 1024 GB file size.

-KjB

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
Reply
0 Kudos
kukacz
Enthusiast
Enthusiast

Your question doesn't sound too clear to me. Are you asking what block size to set for the filesystem you are going to create inside a virtual machine (NTFS, ext3, ReiserFS)? That's the case if you are using raw device mapping. The answer would be: the same blocksize like you would use on physical server, ie. it depends on your typical file size. If not sure, just keep the defaults (4k usually), you wouldn't be wrong in most cases.

--

Lukas Kubin

Reply
0 Kudos