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SAN Transport on VMware VSAN

Level 2


We recently deployed a new VM infrastructure using Vmware VSAN 6.0

It's running in 10G network and the netbackup 5230 appliance is using the same network for backup.

Currently backups are running over LAN method which has some speed limitation on VMware kernel side.

I would like to know if VSAN is supported for SAN Transport to maximize the backup speed. Based on the Veritas Education videos online, it is supported but I dont know how to enable it. I cant find any documentation about it as well.

Please help.


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NetBackup supports VSAN but I'm not sure if it will support actual SAN Transport in the backup method. Having said that, the Infobits video is a bit misleading in the sense that it depicts the VSAN as being contained on what seems to be an external or SAN disk.

I'm not saying that such a configuration is not possible but the idea behing VSAN is providing a VIRTUAL SAN that is made up of internal storage from multiple ESXi Hosts. An important component of VSAN is the VmKernel Network that would distribute the reads/writes between hosts that contain copies/pieces of the data. VSAN makes sure to have multiple copies of the data so that it can tolerate one or more host failures.

So if we look at the video again, configuring VSAN on SAN that is shared between the hosts doesn't really align with the concept as all of the hosts have access to the SAN so why would you need VSAN? I suppose there might be some use case but I can't think of one now.

So back to your question. If you've configured VSAN as shown in the video then I suppose SAN transport might work if you give access to the luns as one would in non-VSAN configuration (not really sure about this one). But if you've got a VSAN configured in the traditional sense, the disks would all be contained in the ESXi hosts, so there is no way that NetBackup can access them via SAN transport, as there really is no SAN.

Does that make sense?

Yes I understand the concept. But the video confused me as well because it shows that Netbackup is accessing the VSAN datastore like a regular SAN. I can't find any documentation on how to make that work. I dont know how to present the VSAN to NBU as if it's a regular SAN storage.

Currently the backup speed is just runs below 100mbps even if the network between the storage and netbackup appliance is 10G. As per the vendor I talked to, it's a limitation hardcoded in the vmkernel level. 

I just had high hopes when i saw the video about VSAN and NBU.


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I also agree that video is confusing. I think that "NetBackup support for VMware vSANs" currently means only support for intelligent VMware policies (DatastoreType Equal "vsan" etc.) and Resource Limits (Max number of snapshots per DatastoreType).

The task how to present internal disks in ESX hosts to external non-ESX (backup) servers is rather question for a SAN/storage guru, IMHO it is not possible, too.

However  in Release Notes for VMware vSAN 6.5, there is this note: "VSAN 6.5 now allows physical server access via iSCSI". ( Maybe that the point you are looking for. However this is very new info and support for backup applications is not mentioned.





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As i said it not possible to present vSAN to or via the SAN, because, as the name says, its Virtual, its not really SAN. Only hosts that are part of the vSAN can access it. Maybe in future as Michal said it might possible via iSCSI.

I suppose you're not using any deduplication storage that is supported by Accelerator otherwise the speed would be better.

Level 4

Old thread but it is still valid. Unfortunately the whole topic is poorly documented from NetBackup side.

First of all the posted video is not only confusing for first sight but in fact it is very misleading. The person who created the drawing on the white board should have at least checked some basic details with his colleagues before putting it into the public. Clearly this video is more about the NBU intelligent policies rather than anything related to VMware VSAN compatibility in general. Generally speaking VSAN and SAN transport are two completely different things and are absolutely incompatible with each other. VSAN as a name is valid just from marketing point of view but in fact it has nothing to do with true SAN infrastructure. Furthermore if you don't particularly work with SAN Transport in NBU you wouldn't even know where to find the hidden details about what is going to work at all and what is to be abandoned at the conceptual level.

So long story short - SAN transport is not only NOT compatible with VMware VSAN but actually it is disabled by default whenever VSAN is detected on a particular host. At the moment you just can't use any combination of the two technologies and this is due to the limitations set in the VDDK. Check out the following link for more details:

Not that we could blame this onto NBU but the product is using an external framework for its tighter integration and therefore NBU should have at least had this limitation outlined in the release notes. I had to figure it out myself the hard way after realizing that my already built SAN Transport is not working anymore. For me NBU was constantly reporting back with "ERR - Error opening the snapshot disks using given transport mode: san Status 23" messages and it took me quite some time to realize what was going on due to the very ambiguous output data generated at the highest log verbosity.

Anyway... lesson learnt, don't take anything for granted even though there are no initial signs of either incompatibilities or limitations. While the release notes weren't mentioning anything about my particular situation I still managed to fall into the trap quite successfully yet I can still feel somewhat lucky that in my case it was an enlightenment from troubleshooting experience rather than a dumb implementation caused by a misleading video (and to be clear I blame the vendor for this...).

I have another similar example with information hidden in the VDDK which is from almost a decade ago when I first tried to implement iSCSI SAN based Transport for my VMware environment (I think it was VCB at the time being). Everything was fine till the point I tried it onto a virtualized NBU media server. While technically this solution should work, the VDDK limitations are pretty much clear on the mandatory requirement for a physical host. The ultimate result was just a whole bunch of NBU error messages but once again without clear statement from the vendor on why is that. Obviously those limitations are set on purpose not because of real technical incompatibilities but due to the lack of enough testing scenarios and most probably marketing departments had their own share for setting the margins but all in all the lack of clear statement is absolutely inexcusable.

Anyway just for the record I'm currently using NetBackup 8.0 with VMware vSphere 6.5 + VSAN 6.6.

SAN transport will not work with VSAN .Here is one vmware document which states it:-