Direct SAN access and vRDMs

[pinkerton]

Hi,

since replication with VBR6 and vSphere 5 is working so great we are considering to replicate some servers that are currently using pRDMs as well. I know we need to change the type of the RDMs from physical to virtual before this is going to work, but that is not going to be a problem.

My question is whether vRDMs can be read with Direct SAN access as well and if is suitable enough to just present the RDM-LUN to the VBR server. Since the partition on the RDM LUN is formatted directly with NTFS I know that I need to take special care with presenting the LUN to the VBR server. Am I correct in assuming that the LUN needs to be ONLINE in Windows disk manager but a drive leter must not be assigned?

Thanks
Michael

[Patje]

Hi Michael,

As far as I know, this not possible.
you cannot present a NTFS volume to 2 windows hosts at the same time
Even if you don't present a drive letter, windows will try to put a signature on the disk and you do NOT want that.
VBR will only backup native VMDK files.
You should be able to backup the virtual machine, but the not the vRDM.

If there is a workaround, I'd like to know as well.

grts,
Patrick

[pinkerton]

Hi Patrick,

I've just tested this. The VBR server is 2008 R2 and I can present the vRDM to Windows without any problems, making it online in disk manager however does not make it available for Direct SAN Access in Veeam. When performing a backup of a VM with a vRDM configured and failover to NBD is NOT enabled, I get the following result:



The backup fails right away. And strangely the vRDM disk is the first disk being backed up, not the system disk (VMDK).

When enabling failover to NBD on the backup proxy, I can successfully backup the vRDM and once finished it automatically switches back to Direct SAN access for the system disk (VMDK):



So, anyone know whether it is possible to backup a vRDM disk using Direct SAN access? This would be very useful, since we use RDMs only for large disks where Direct SAN access would make much sense.


Thanks,
Michael

btw: NTFS disks can be presented among Windows systems without any problems. You just need to be careful when presenting disks that have different file systems on it. But even with immense testing I was not able to have Windows (2008R2) write a new signature on a VMFS volume.

[Patje]

Michael,

Thanks for the info, I was not aware NBD would backup the vRDM, good to know.
I do agree, it would be nice to use Direct San for vDRM's
I'm curious as to why this is not possible since the backup server is able to see the volume, hoping someone from Veeam can shed some light into this.

regards,
Patrick

[pinkerton]

I'm opening a case with support and ask them whether this is possible or not. Would indeed be good if this was possible.

[Gostev]

This should definitely work in both hotadd and network mode. As for direct SAN access, I am not sure (frankly, until your post I thought that this works fine). I will need to wait for devs to come back from New Year holidays, and will check with them on that. Please do open a support case (and post the support case ID), as having the logs handy will certainly help me get the answer faster. Thanks!

P.S. I still think everyone should get rid of vRDMs and go with VMDKs you are not fully virtualized until your storage is virtualized as well.

[pinkerton]

Thanks Anton, Case ID is 5164362. If the devs say it should generally work I'll do another test and send logfiles!

[pinkerton]

In order to send clean log files to support I repeated all steps today:

- Added the vRDM to the VM
- Presented the corresponding LUN to the VBR server
- Created a new backup job with the VM

And now everything worked fine. Yesterday I only used "Manual Selection" in the Backup Proxy Settings and presented the LUN with only one path, today I tried "Automatic Detection" and used four paths. However, even repeating the steps form yesterday wíth Manual Selection and one path Presentation worked fine today. It even worked if the vRDM LUN is available in Windows Disk Management but set to Offline.

Actually everything worked today as long as the vRDM LUN is presented to the VBR server.

Will change a production pRDM to vRDM on the weekend and then run the initial replication during the weekend (1TB). Then we can use CBT incremental replication for our file server as well

Thanks all for your help!

[ivglukh]

Anton, what is the latest on this topic? Will SAN Direct Access work with Virtual RDM?

Thank you!

[Vitaliy S.]

Based on the OP support case notes it does seem to work.

[spgsit5upport]

In my environment I can not get vRDM disks being backed up by Direct SAN access, it does give me the same warning as in original pinkerton's message: "Unable to establish direct connection to the shared storage (SAN)."

vmdks being backed up by [san], but vRDM are NOT

[Gostev]

Remember to include support case ID whenever posting about any technical issue, otherwise we will not be able to take any action on your issue. Thanks.

[spgsit5upport]

But I do not have any case ID. I might open case, but it often more hustle then find a solution in a different way (talking from experience so far in the last x years using Veeam)

[Gostev]

You are more than welcome to try and find the solution by searching the existing topics. For example, as you can see from this topic, there are no known issues with Direct SAN access and vRDMs. However, if you chose to post about an issue, we require that support case ID is included. We have introduced this a requirement for a number of reasons. Please review the corresponding forum rules for more information. These are provided when you click New Topic.

There is absolutely no hustle in opening a support case, it takes less than a minute at our Customer Support Portal, and you will immediately get a support case ID to include with your forum posting.

Here is another helpful thread you may want to take a look at > Direct SAN access failure troubleshooting

Thanks!

[spgsit5upport]

The hustle is to deal with the issue later. I am yet to get good support guys to actually do something good , so far that was never a case, and it involves a ping pong of e-mails (mostly waste of time)

[foggy]

Seb, you can always ask to escalate the case to a manager, if you feel you are wasting time in e-mail conversation. Also, our support is always ready to set up a webex session with you to troubleshoot the issue more efficiently.

[spgsit5upport]

Last time I had webex session it was just a waste of time (honestly). The time that I do not have...

[danswartz]

Hustle? Do you mean hassle?

[spgsit5upport]

Yes I do.

In fact I went through the logs & it turned out that it was a SINGLE vRDM that was being backed up network.
And this was correct, as that very LUN was on an array that was NOT accessible to the Veeam server.

As it was the first (in order) vRDM attached to this server, I simply assumed (wrongly) that it applied to all of the vRDMs

The Job Statistics summary screen does not make it obvious (in that case) that the message applied to ONLY one LUN

But all is well

Seb

[foggy]

Seb, glad you've nailed it. Thanks for the update.

[luckyinfil]

I have a requirement to backup a VM with a vRDM. With regular vmdks, the zoning is straight forward - just zone the LUN to both the ESXi hosts and the physical veeam server in order to backup over the FC.

In order to backup vRDMs over SAN mode, how do you zone the LUNs? There's the vRDM LUN as well as the LUN where the VMDK and the vRDM pointer files are stored.

[Vitaliy S.]

Hi John,

I believe you should give access Veeam backup server to both LUNs, with the pointer and with actual data. Please see this topic for more details.

Thanks!

[luckyinfil]

Thanks. Just wanted to confirm that both the vRDM LUN and the LUN where the vmdks and vRDM pointer files are located must be visible to the Veeam Backup Proxy.

[veremin]

Hi, John, thank you for taking time and updating the topic with your findings; much appreciated.

[BriFar]

Thanks. Just wanted to confirm that both the vRDM LUN and the LUN where the vmdks and vRDM pointer files are located must be visible to the Veeam Backup Proxy.

Doing this does not allow you to backup the vRDM in SAN mode right? I am asking because in your previous post you mentioned you wanted to use SAN Backup. It is also stated in the helpcenter that "Also, consider that backup for vRDM disks in the in Direct SAN Access mode is not supported."

see
http://helpcenter.veeam.com/backup/70/v ... ccess.html

In all my testing, for a customer with 30+ VMs all with pRDMs, it always failed over to NBD. I tested with one VM converting to vRDM. It would be really good if SAN mode was supported as it would spare me from doing storage vmotion on all the LUNS to VMDKs.

Since SAN mode backup is not supported on vRDMS I would not present these LUNs to the Backup Proxy. Mainly to keep it clean and to avoid issues i.e make the drive online by mistake.

[foggy]

Doing this does not allow you to backup the vRDM in SAN mode right? I am asking because in your previous post you mentioned you wanted to use SAN Backup. It is also stated in the helpcenter that "Also, consider that backup for vRDM disks in the in Direct SAN Access mode is not supported."

see
http://helpcenter.veeam.com/backup/70/v ... ccess.html

After short investigation it turned out that this note was put in help by mistake. Thanks for pointing that out!

In all my testing, for a customer with 30+ VMs all with pRDMs, it always failed over to NBD. I tested with one VM converting to vRDM. It would be really good if SAN mode was supported as it would spare me from doing storage vmotion on all the LUNS to VMDKs.

Generally, backup SAN mode should work for vRDM (not pRDM, which are automatically skipped during processing), so probably some configuration issue. Support could help in verifying the environment.

[BriFar]

Hi foggy,
support told me that vRDM do not support direct SAN backup and pointed me to the note I linked before.
Case No. 00544200.
In that case I had an issue with the particular VM but the final note was still that SAN mode Backup was not supported for vRDMs. For the sake of this thread I quickly installed a 2008 SP2 on a vRDM disk. The vRDM LUN and the LUN where the vm resides were presented to the backup server. To my surprise it backed up in SAN mode.
I am sure I did the same test after the case was closed and it failed over to the network mode.

Sorry all if I confused anyone with the previous reply and thanks foggy for persisting that SAN mode for vRDM is supported.

[foggy]

Brian, thanks for sorting this finally out. I will approach support guys involved in your case with this to avoid confusion in future.

[sani]

Hi

i have a vm with virtual RDM disk and backup job works fine with network.can i backup from this vm with Direct SAN(Lan free)?

thanks

[MichaelCade]

I have not tested this recently but I am confident providing the LUN is masked also to the Veeam proxy that DirectSAN can be achieved.

Access should be read-only for all LUNs (VMFS and/or RDM) from the storage array configuration.