New subject: NFS vs. iSCSI for VMware (was "Re: List still active?")

12 Jul 2007

      Vaughn:
...
NetApp covers this technology in their VMware Storage Best Practices
paper, TR3428.
You're way too modest....you WROTE that TR......
:)
Glenn @ Voyant
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-----Original Message-----
From: owner-toasters@mathworks.com [mailto:owner-
toasters@mathworks.com] On Behalf Of M. Vaughn Stewart
Sent: Wednesday, July 11, 2007 10:53 PM
To: Scott Lowe
Cc: Davies,Matt; toasters@mathworks.com
Subject: Re: NFS vs. iSCSI for VMware (was "Re: List still active?")
Scott,
Your comments on the 2x the space for a NetApp is LUN is a bit
misleading and is out of date.
NetApp LUNs do NOT require any additional space.  i.e. 50gbs = 50gbs
If you want to take a snapshot of that LUN you had to ensure that you
had additional capacity in case the volume became full in which case
the
snapshot function would be disabled until manual intervention deleted
old snapshots.  In this design NetApp did not defferentiate the value
of
production data and snapshot data, so a requirement of a reserve
equaling 100% of the LUN size was required.  i.e. 50gb = 50gb + 50 gb
+
...
snapshot space.
This design seemed inefficient when compared to snap reserves with NAS
data, but when compared to other SAN vendors and their n disk backup
mechanisms, it was extremely space efficient.  I wont go into details
here but to say that enterprise class on disk backups with traditional
arrays require 100% overhead for each individual backup.
Today NetApp offers a means where one can say production data is more
valuable than snapshots.  They provide two dynamic space management
policies, auto vol grow and auto snapshot delete.  With these two
policies you can eliminate any additional LUN overhead and should a
volume run out of space the appropriate policy will be enforced and
will
ensure that production data remains online.  Now 50GB with snapshots =
50GB + snapshot space only!
NetApp covers this technology in their VMware Storage Best Practices
paper, TR3428.
Vaughn
Scott Lowe wrote:
...
The #1 complaint I have about using iSCSI relates to how LUNs are
handled in the NetApp world:

You have to (by default) allocate 2x + deltas for LUNs.  For a

100GB LUN, you'd need 240GB of space (by default--I know there are
workarounds with ONTAP 7.2 and later).  With an NFS mount (which is
nothing more than exporting a FlexVol), you only need to account for
the 20% Snapshot reserve.

You can't resize iSCSI LUNs.  With NFS on a FlexVol, you can

resize to your heart's content because WAFL is controlling the
filesystem--not the host.

It's open, meaning that your VMDKs aren't locked into the

proprietary VMFS file system.  This could potentially simplify
backups
...
and restores.
As Glenn @ Voyant already mentioned, you also gain thin provisioned
disks by default and more knowledge/history/experience with NFS than
with iSCSI.
Thanks,
Scott Lowe
ePlus Technology, Inc.
slowe@eplus.com
On Jul 11, 2007, at 9:34 AM, Davies,Matt wrote:
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Scott,
Any chance you could expand on the advantages of NFS over Iscsi ?
NFS
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isn't an area I have any experience of....
Cheers
Matt
-----Original Message-----
From: owner-toasters@mathworks.com [mailto:owner-
toasters@mathworks.com]
...
...
On Behalf Of Scott Lowe
Sent: 11 July 2007 14:05
To: Forest Leonard; toasters@mathworks.com
Subject: Re: List still active?
Forest,
When it comes time to configure VMkernel for VMotion, then I'd
definitely recommend keeping it separate from the virtual machine
network.  As it stands right now, you don't even need a VMkernel
NIC
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configured because it sounds like you are using Qlogic iSCSI HBAs
and
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only have a single ESX Server.  Since the Qlogic cards handle the
iSCSI traffic and there is no VMotion, there no current need for a
VMkernel NIC (unless you want to use NFS from the FAS to provide
additional storage for VMs--which, by the way, works pretty well
and
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has some nice advantages over iSCSI, IMHO).
Regards,
Scott Lowe
ePlus Technology, Inc.
slowe@eplus.com
On Jul 11, 2007, at 8:33 AM, Forest Leonard wrote:
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Interesting stuff. I only have one ESX server so I haven't gotten
to the
Vmotion configuration yet.. That should be later this year.
I just configured a RDM to run a Virtual server on. I found an
article
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where you want to create the type as NTFS if it is a RDM for a
windows
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host. Not sure if I am going to use this going forward. I actually
don't
know if you can migrate into a RDM. It doesn't look like it.
I am only using 2 NIC's on my Vmware server.. and a QLOGIC card
for
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my
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ISCSI access.. I may need to look at bulking up my NIC
configuration. It
looks like I may gain some performance if I separate my VMKernal
from my
Virtual Machine network?
Thanks,
Forest
-----Original Message-----
From: Davies,Matt [mailto:MDAVIES@generalatlantic.com]
Sent: Wednesday, July 11, 2007 8:18 AM
To: Forest Leonard; ggwalker@mindspring.com;
toasters@mathworks.com
...
...
...
...
Subject: RE: List still active?
Sounds like we are both at the same stage.
We are not using RDM's yet, however when it comes to exchange we
will
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have to, or I may just stick with using the Microsoft Iscsi
initiatator
from within the VM, not exactly supported, but I know of other
people
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doing it.
We have migrated 8 machines so far, into just one datastore and
have not
seen any performance problems at all, although most of the
machines
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have
very low IO requirements.
We are using a script to snapshot and then replicate using
snapmirror,
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it works very well, however our Virtual Centre server is also a VM
which
was causing a few problems with the snapshots on the VMware side
not
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being removed, but moving this to a separate datastore seems have
cured
the problems, even SQL doesn't seem to have a problem.
The script is the one written by Evan Battle, that is in the
newest
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netapp docs on VMware. I did have a few problems with ssh to the
filer,
but we are now using rsh and it seems to be ok.
I don't know how you have setup your virtual switches on the ESX
side,
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but I got some best practice information out of VMware on that
subject.
Each of our  ESX IBM3550  host servers have 6 Nics, connected as
follows.
2 Nics for service console VMKernel for Vmotion, load balance
using
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Virtual port ID
2 Nics for Virtual Machine network, load balance using Virtual
port
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ID
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2 Nics for ISCSI (Service Console and VMKernel), load balance
using
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IP
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Hash
Hope this helps....
-----Original Message-----
From: Forest Leonard [mailto:fleonard@rvigroup.com]
Sent: 11 July 2007 11:06
To: Davies,Matt; ggwalker@mindspring.com; toasters@mathworks.com
Subject: RE: List still active?
Hey Matt... I am actually doing the exact same thing on a FAS
270..
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I
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have migrated about 7 servers so far.
Are you using RDM's (remote device mappings) for the Virtual
Machines? I
actually just created 2 200GB LUNs on the netapp to use as
Datastores
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and have not had any performance issues.
Just wondering what your experience with RDM's are.. I added one
into a
virtual machine.. It just lets you map a LUN directly to a Virtual
machine.
Has anyone out there used the netapp script to capture a VM
snapshot?
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...
Thanks,
Forest

From: owner-toasters@mathworks.com on behalf of Davies,Matt
Sent: Wed 7/11/2007 1:00 AM
To: ggwalker@mindspring.com; toasters@mathworks.com
Subject: RE: List still active?
Still working by the looks of things.
busy in process of migrating all our physical severs to VM, stored
on a
iscsi lun on a FAS 270.
For those that want to know we are using the software iscsi
initiator
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within ESX and have not had any problems so far.
cheers
matt
-----Original Message-----
From: owner-toasters@mathworks.com owner-toasters@mathworks.com
To: toasters@mathworks.com toasters@mathworks.com
Sent: Wed Jul 11 01:03:49 2007
Subject: List still active?
I've noticed that I'm still subscribed, but have received no email
since
July 4th.  Everyone didn't trade their NetApp gear for something
else
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while I was out of town did they?? J

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RE: NFS vs. iSCSI for VMware (was "Re: List still active?")