extents temporarily not visible

[owiegmann]

I have one netapp storage and two vmware vi3-hosts with one iscsi lun. In the last week i must add some new place. I do this by extend the lun on the netapp. On the vi3-hosts i have one datastore with two extents. After i added the space by a third extent i have the problem that some vm´s crashed. During the toubleshooting i saw that the extents will temporarily not visible on the vi3-hosts. After a rescan of the storage adapater i can see the extent but some time later they are unvisible. It is possible that the problems with crashed OS of the vm´s have to do with the unvisible extents? To solve the problems i add a new lun and move the vm´s to this place. I this the right way?

[christianZ]

Basically to add an extend in not prefferd method to expand the volume - better is to create a new (bigger) lun and move your vms into it.

Of course it isn't always possible to do that this way (you may have enough empty space on your storage). So I would prefer this method always when possible.

I'm not sure whether there are any running vms allowed by adding an extent to their volumes.

[owiegmann]

Hello christianz,

Thank God i have enough space on the storage. In the moment i migrate the vm´s to the new lun and boot them up. Currently it´s looks good. I don´t know wether it is the right way to expand a vmfs-Volume with extents? What is the best practice in this cases? In the moment i think it is better to build more lun´s respectively more vmfs-volumes?

Thanks for your answer

[christianZ]

You are right - it should be better to configure more smaller luns (for ~ max. 10 vms) than only a few bigger luns. In that case it would be simpler to create a new bigger lun and move all vms into it.

Basically I would prefer storage system with "thin provisioning".