SAN question

lordsegan

Gawd
Joined
Jun 16, 2004
Messages
624
Question: do FC SANs have two layers of file systems? For example, the first layer being ZFS to create a comstar LUN and then you format the LUN to NtFS from the windows client?
 
Yes,
a Comstar LUN is a ZFS filesystem/Zvol that is presented like a RAW disk that you can format with any filesystem.
 
Basically yes, but only when a LUN is in use.

So a LUN is a Logical unit Number, to a SAN a LUN is just a file sitting in a Volume, the SAN doesnt care what is inside the LUN its just a file (it doesnt care as it leaves everything upto the client).

The LUN once created can be mounted to another system as a Raw Data Mapping(such as adding a drive to a windows host) in this case the LUN would be formatted with NTFS.

In a VMware system a LUN could be mapped as a datastore and would be formatted with VMFS(Virtual machine File System) Then you would have a VMDK(Virtual Machine Disk) which you could install a client onto such as windows therefore formatting the VMDK as NTFS.

So yes there can be multiple layers, and multiple file systems.
 
If you wanted, you could assign a raw disk as a lun in comstar, but people rarely do this, cause you loose all the data protection of zfs.
 
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