ESX3 san storage for data separate from san storage for vm

[lynxms17]

I have an MSA1000 and 3 ESX3 servers. To date I have a single LUN associated w/ each ESX server hosting the associated VM's. So far the VM's I have are small task oriented servers and workstations which require little data storage. I am now going to start converting my ‘datastorage' servers to VM's. The current ‘datastorage' servers have their data out on the SAN under their own LUNs. I'm wondering if as I convert these systems to virtual machines, if I shouldn't keep their data out on their own LUN. IE:

Currently I have:

SAN_LUN_1

SAN_LUN_2

ESX_Host_1

ESX_host_Datastore on SAN_LUN_1 (hosting VM)

Physical_Server_1

C: local

D:on SAN_LUN_2

When I convert this system to a virtual:

SAN_LUN_1

SAN_LUN_2

SAN_LUN_3

ESX_Host_1

ESX_host_Datastore on SAN_LUN_1 (hosting VM)

ESX_host_Datastore on SAN_LUN_3 (hosting data)

Virtual_Server_1

C: on ESX_host_Datastore on SAN_LUN_1 (hosting VM)

😧 on ESX_host_Datastore on SAN_LUN_3 (hosting data)

I would then remove SAN_LUN_2 as it would no longer be used to store data for the old Physical_Server_1. Could I then also move the 😧 drive between virtual machines? If the OS on Virtual_Server_1 gets messed up by an OS update, patch, application etc ... could I simply roll out a new Virtual_Server_1 and associate the existing datastore w/ this new server?

[virtualdud3]

If I understand your question properly, yes, you should be able to associate an existing virtual disk with multiple VMs.

[lynxms17]

My scenerio confuses me too. I guess what I'm looking at is: I have a current physical machine that has a LUN on the SAN w/ 250Gig used for data storage associated w/ that server. When I convert this sytem to a virtual, I'm not sure that I want to convert the entire system into a single LUN or Datastore. Would I be better off converting the OS into a LUN/Datastore of its own and the data into a LUN/Datastore of its' own. Would Consolidated Backup handle this better one way or the other? If I need to expand my LUN and Datastore to allow for more data storage ... is a seperate LUN/Datastore preffered?

[virtualdud3 · Accepted solution]

The answer is "It Depends" : - )

Typically, you want to have the OS and data running on separate virtual disks. In your description, you would have each virtual disk on its own LUN. To use VCB, the VCB proxy server will have to "see" (have connectivity to) both LUNs.

There really isn't much you can do when it comes to "expanding" LUNs - you can either add an extent (not recommended) or just create an additional LUN. The reason extents are not recommended is that if something happens to one of the LUNs, you lose the entire datastore (not good) as the metadata are only stored on the primary/first LUN.

You can also look at RDMs...

Here is a link you might find useful:

http://www.vmware.com/pdf/vmfs-best-practices-wp.pdf

[lynxms17]

Thanks for the input and the link to the best practices. I have had pretty good success w/ increasing my virtual disks using vmkfstools and gparted. That has been done on systems that are wholey contained w/in a datastore and I have yet to try to make any changes to a datastore.

[virtualdud3]

Ahhh -

To clarify, increasing the size of a virtual disk is straightforward (as you already know).

I was referring to increasing the size of a LUN itself (which you cannot do; you have to add an extent).

[lynxms17]

I am able to increase the size of my LUn on my MSA1000 from w/in my Array Config Utility. I assume you mean I need to add extents to increase the size of my datastore?

[lynxms17]

sorry ... I see what you mean .. LUN w/ ESX ... not on the MSA

[virtualdud3]

Exactly.

Please consider awarding points if you found any of the responses helpful or correct. Thanks!!!