seangar
Contributor
Contributor

NFS vs VMFS iSCSI

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We have one VC Cluster set up with VMFS and iSCSI.

We are thinking that NFS will buy us simpler backup (NetApp SNAP). This will be our second cluster.

Regarding this:

1. will we be able to migrate VMs (cold) from VMFS to NFS so we could eventually get rid of the VMFS all together ?

2. Are there any drawbacks to NFS over VMFS (vmotion, HA, DRS etc all work the same) ?

3. Does NFS require same type of setup (iSCSI initiator, a SC, and Kernel also like our VMFS we have set up currently) ?

Note that VMworld 2007 (which I attended) had plenty of presenters touting NFS of VMFS and they all claimed performance was not an issue except over a WAN. WAN is not a concern for us.

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pdrace
Hot Shot
Hot Shot

Check out

http://www.vmware.com/pdf/vi3_301_201_server_config.pd

f starting on page 132.

ESX still creates VMFS partitions on NFS.

Are you sure about that?

I don't think NFS volumes were formatted as VMFS.

From the config pdf page 91:

File System Formats

Datastores that you use can have the following file system formats:

VMFS – ESX Server deploys this type of file system on local SCSI disks, iSCSI

LUNs, or Fibre Channel LUNs, creating one directory for each virtual machine.

VMFS is a clustered file system that can be accessed simultaneously by multiple

ESX Server systems.

For more information on VMFS, see “VMware File System” on page 97.

As an alternative to using the VMFS-based datastore, your virtual machine can

have direct access to raw devices using a mapping file (RDM) as a proxy. For more

information on RDMs, see “Raw Device Mapping” on page 151.

NFS – ESX Server can use a designated NFS volume located on an NFS server. ESX

Server mounts the NFS volume creating one directory for each virtual machine.

From the viewpoint of the user on a client computer, the mounted files are

indistinguishable from local files.

Message was edited by:

pdrace

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pdrace
Hot Shot
Hot Shot

We have one VC Cluster set up with VMFS and iSCSI.

We are thinking that NFS will buy us simpler backup

(NetApp SNAP). This will be our second cluster.

Regarding this:

1. will we be able to migrate VMs (cold) from VMFS to

NFS so we could eventually get rid of the VMFS all

together ?

I'm not sure about this but I would think you could.

2. Are there any drawbacks to NFS over VMFS (vmotion,

HA, DRS etc all work the same) ?

All should work assuming the NFS volumes are available to all the hosts in a cluster.

3. Does NFS require same type of setup (iSCSI

initiator, a SC, and Kernel also like our VMFS we

have set up currently) ?

No you don't need these for NFS.

Note that VMworld 2007 (which I attended) had plenty

of presenters touting NFS of VMFS and they all

claimed performance was not an issue except over a

WAN. WAN is not a concern for us.

I would have liked to try NFS on our NetApps but I don't have a license which is pretty pricey.

InfoStewards
Enthusiast
Enthusiast

Check out http://www.vmware.com/pdf/vi3_301_201_server_config.pdf starting on page 132.

ESX still creates VMFS partitions on NFS.

All of the VMotion, HA, DRS features work the same.

You can cold migrate VMs between local VMFS/iSCSI/FC to NFS.

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pdrace
Hot Shot
Hot Shot

Check out

http://www.vmware.com/pdf/vi3_301_201_server_config.pd

f starting on page 132.

ESX still creates VMFS partitions on NFS.

Are you sure about that?

I don't think NFS volumes were formatted as VMFS.

From the config pdf page 91:

File System Formats

Datastores that you use can have the following file system formats:

VMFS – ESX Server deploys this type of file system on local SCSI disks, iSCSI

LUNs, or Fibre Channel LUNs, creating one directory for each virtual machine.

VMFS is a clustered file system that can be accessed simultaneously by multiple

ESX Server systems.

For more information on VMFS, see “VMware File System” on page 97.

As an alternative to using the VMFS-based datastore, your virtual machine can

have direct access to raw devices using a mapping file (RDM) as a proxy. For more

information on RDMs, see “Raw Device Mapping” on page 151.

NFS – ESX Server can use a designated NFS volume located on an NFS server. ESX

Server mounts the NFS volume creating one directory for each virtual machine.

From the viewpoint of the user on a client computer, the mounted files are

indistinguishable from local files.

Message was edited by:

pdrace

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Curdasss
Hot Shot
Hot Shot

NFS is not formatted as VMFS. Not sure about the performance difference between NFS and VMFS, VMware pushes VMFS as a high performance file system so I would say that VMFS is faster. You cannot run DRS or HA on NFS, you can use VMotion.

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pdrace
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Hot Shot

3. Does NFS require same type of setup (iSCSI

initiator, a SC, and Kernel also like our VMFS we

have set up currently) ?

No you don't need these for NFS.

Correction you do need vmkernel for NFS access. You don't need an additional SC or ISCSI initiators.

pdrace
Hot Shot
Hot Shot

NFS is not formatted as VMFS. Not sure about the

performance difference between NFS and VMFS, VMware

pushes VMFS as a high performance file system so I

would say that VMFS is faster. You cannot run DRS or

HA on NFS, you can use VMotion.

Have you tried to setup HA/DRS with NFS datastores?

Iwould think it would work since vmotion can be used.

The resource management guide says they require shared SAN storage.

I think NFS volumes on a SAN would qualify.

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team-ip-service
Enthusiast
Enthusiast

Hi seangar,

my colleague ask me the same since the start of our vmware environment (Feb 2007).

Since we are all TCP/IP Ethernet guys and no native Storage Men exists, we're using NFS for most of our things and iSCSI for vmware (Since VMWare always told the NFS is not a good choice). But NFS for VM's would make our lives easier.

Snap Shot, Storage over subscription and VMWare use thin disk as default. We mostly running small linux server inside the VM's and would benfit from not reservating to much diskspace.

So maybe you can tell me your decision about NFS vs iSCSI and your exprience.

Markus

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