Storage VMotion - iSCSI support

[jbaxter714]

I went to VMworld and went to the Storage Vmotion discussion, and have read most of the literature on it. Just came across this statement that Storage VMotion would only be support on fiber-channel disks.

From the VMworld discussion and other sources, I thought one main selling point of Storage Vmotion was to enable movement of virtual machine storage from heterogenous array to heteogenous array. I liked the idea of being able to move from local storage to iSCSI to fiber-channel, etc.

Since the copy is network-based (right?), why is it restricted to FC SAN at the moment? Seems as if the ESX box can see both storages sources, it should be able to copy it over..

I'm most interested in iSCSI support...

[Texiwill]

Hello,

vMotion works on any shared storage system: iSCSI, SAN, Shared SCSI, and NFS.

Best regards,

Edward L. Haletky, author of the forthcoming 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', publishing January 2008, (c) 2008 Pearson Education. Available on Rough Cuts at http://safari.informit.com/9780132302074

[sbeaver]

You are right when Storage vMotion comes out it will be supported on Fiber Channel only to start and no this is not a network based copy it would be file based

Steve Beaver

VMTN Forum Moderator

*Virtualization is a journey, not a project.*

[jbaxter714]

Okay, what do you mean by file-based? Either the copy is done on the SAN via some sort of block-level replication, or it's done over the network. If it's done over the network, then I don't understand why the type of back-end SCSI access matters - FC or iSCSI. As long as the drive is mounted and the ESX host can see the .vmdk files...

I went back to review the VMworld presentation on Storage VMotion to make sure I wasn't mistaken.

Slide 11 says "Migrate from FC to iSCSI, NAS, or within or between enclosure(s)"

Slide 19 is even titled "Storage Type Agnostic" and says "Copiers not storage type specific", "located above filesystem layer" "Source and destination can be different storage types." and shows a diagram with SAN, iSCSI, Local, and NFS.

I know VMworld is just a "futures" but clearly the product was so close to coming out, I'm wondering why they made it FC only when it's clearly designed to be storage agnostic from the get-go...

[sbeaver]

Storage vMotion will be done on the SAN not the network

[chrisy]

On the SAN? Surely not. That would mean no migration to / from direct attach storage or NAS boxes. It would also be a challenge to allow the SAN to do all the work moving a single VM from inside a VMFS volume.

'Site recovery manager' is SAN-powered, except that one will support iSCSI.

If storage VMotion is only involving FC SANs, and only SAN volume to SAN volume, I don't see the point. You could create RDMs and move them around with the SAN anyway, without needing a new VMware feature?

--

Chris

[jbaxter714]

I really really doubt Storage VMotion will happen on the SAN. That would contradict everything that I've seen on this, including the entire Storage VMotion presentation given at VMworld just a month or two ago....

[WillemB]

First of all i wasn't at vmworld and got my info second hand.

The idea with storage vmotion is the same as memory vmotion.

1. First the datafile is set to snapshot mode so it is read-only and a new file holds the changes (delta file).

2. Then the data is copied to the other side.

3. Then the delta file is copied until it is small enough so that the server can switch over with close to no delay.

Why fiber SAN only? I can only assume that if you have a slow(ish) network it will take ages and the delta file might never get small enough to do a switch over.

For me storage virtualization would be a good way to empty a NAS/SAN for maintenance or resorting the resources.

[AnthonyM]

I was talking about this with our VMWare supplier yesterday (ACR Technologies in the UK, they were at VMWorld).

We have an ESX Starter server that we want to move to an Enterprise, two server set up.

As far as he was concerned, we could simply update ESX when 3.5 comes out, update the licensing, connect to the iSCSI (Equallogic) LUN, and do the Storage VMotion, then set up HA to load blanace the two servers.

As far as he was aware this would work, with no VM downtime, but he is attempting to confirm this with his sources at VMWare.

That implies to me that the Storage VMotion must work with all types of storage.....

[davidbarclay · Accepted solution]

>

Why fiber SAN only?

They do this with everything. They limit the scope to test and release quickly. I'm sure if you surveryed 60-70% of established VMware is on FC anyway.

Dave

[BUGCHK]

> On the SAN?

The ESX server reads the data from the source datastore via the Fibre Channel interconnect and writes the data to the destination data via the Fibre Channel interconnect. No second server is involved.

> move them around with the SAN anyway

You seem to confuse the term storage array with SAN.

[jbaxter714]

Just wanted to follow up on my own post. I cornered someone from VMware a few days ago at an event, and he confirmed the technology actually does work with iSCSI and NAS - it just won't be on the supported list for the first release. As davidbarclay already pointed out (hence I marked him with the correct answer), they do this a lot to be able to test and release quickly.

I expect that the iSCSI and NAS support will be certified soon after release (I hope!) In the meantime, I hope they haven't actually blocked it from working, so I can use it in unsupported mode for testing at least to start.

By the way, I think you'll see the FC market shrink a bit to iSCSI over the next five years, as 10Gig Ethernet becomes mainstream. I have several clients using it already and it makes things a lot easier at times. I hope VMware doesn't continue to treat iSCSI as a second sibling to FC as iSCSI increases its market penetration.

[TomHowarth]

This is directly contary to the infomation I received yesterday Steve, where did you get it? I was informed that FC, iSCSC DAS and NAS will be supported

Kind Regards

Tom,

[sbeaver]

I might be wrong but this was the way that I understood things would work out of the gate.

Steve Beaver

VMTN Forum Moderator

*Virtualization is a journey, not a project.*

[jbaxter714]

As I noted a few posts up, I was told that it would be FC-support only to start by a VMware employee at a NetApp/VMware event just this past Wednesday. He said it would actually work with NAS and iSCSI, but just wasn't supported because it hadn't gone through the QA process yet.

This seems to be backed up by the vmware.com web page and data sheet on the feature, that only list FC support for now.

[Noyzyboy]

This page seems a bit confusing, it seems to imply that Storage VMotion (and Update Manager) is available now. I'm assuming we have to wait until 3.5, anyone got any dates for release?

Cheers,

Rich

[sbeaver]

Rumor has it MAYBE this next month

[Noyzyboy]

Great, I just spoke to our VMware rep here in New Zealand and he said 30th November was been touted as a date. Here's hoping. I have a 3 server install to do before Xmas and it relies on using Storage VMotion to minimise downtime during the migration (MSA1000 to NetApp), might be a close call... :smileyblush:

Cheers,

Rich

[dalepa]

I wish Vmware would clarify Storage Vmotion datastore options. I'm confused (like many others) Which one is it?

1. Does this mean that Storage VMotion works for NFS, iSCSI day one, but just not supported if it breaks?

2. Does this mean that FC is the only protocol that works and NFS and iSCSI will NOT work day one?

3. Has anyone done a Storage Vmotion over NFS or iSCSi yet in the Beta?

From THIS pdf, it says "any storage supported", and the next bulled says "Support for Fibre Channel SAN..." ?:|

Key Features of VMware Storage VMotion

• Complete transaction integrity. Zero downtime storage migrations with complete transaction integrity.

• Interoperability. Complete operating system and hardware independence allows Storage VMotion to migrate any virtual machines running any operating system across any type of hardware and storage supported by VMware ESX Server

• Support for Fibre Channel SAN. Implement live migration of virtual machines disk files utilizing a wide range of up to 4GB Fibre Channel SAN storage systems

-

---

dlp

[jnickel]

I can confirm that it DOES work with iSCSI (even though officially unsupported).

However, with slower iSCSI devices (like my test Linux iSCSI boxes running ietd) I have found that the VM becomes somewhat unresponsive depending on how much disk access the VM is performing.

Sometimes it works fine - other times the machine acts like it is down. I tried this with a web server (does quite a bit of disk IO) and my browser often timed out while trying to retrieve web pages from it during the Storage VMotion.

I suspect that you need a fairly quick SAN (thus the restriction to FC for now) in order to do the move and keep the delta's going at the same time. I am guessing that VMware will adjust this to handle slower SAN disk in a future revision.

Jim