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iSCSI Direct SAN Access with a VM?

Post by SteeleTek » Jun 16, 2016 7:42 pm


In the Veeam documentation, for backup transport modes, it states that "Virtual Appliance" is the recommended mode if my backup proxy is a VM:
"The Virtual appliance mode is not so efficient as the Direct storage access mode but provides better performance than the Network mode. The Virtual appliance mode is recommended if the role of a backup proxy is assigned to a VM." ... iance.html

At the same time, I am able to setup Direct storage access on my Backup Proxy VM by adding the iSCSI target and an additional vNIC on the storage network, to the proxy VM. I also tested and the backup job is able to use that proxy VM for Direct SAN backup.

Question #1: is there a performance benefit in using Direct SAN when my proxy is a VM or is it better to stick with the "Virtual Appliance" transport mode?
Question #2: If I have production VM's residing on various storage platforms (local and iSCSI), can a single backup proxy automatically use multiple transport modes on the same job without issue (ie, Direct SAN for the VM's on my iSCSI SAN and HotAdd for VM's that are on a local disk of the Host)?

Thanks in advance!

I did create a support ticket with these 2 questions but the engineer was unsure (case #01829188).

Product Manager
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Re: iSCSI Direct SAN Access with a VM?

Post by PTide » Jun 17, 2016 12:00 pm

Question #1
There will be no siginficant performance gain in case of a VM-based proxy as in both cases the dataflow will go via ESXi network stack. On the other hand DirectSAN starts backup operation faster as it does not have to attach VM's virtual drives with hot-add an extra delay occurs due to necessity to attach virtual drive to proxy which takes directSAN there will be no delay as it does not need to attach virtual drives to the proxy.
Question #2
Yes, it can use choose transport mode automatically if an "Automatic selection" has been specified in a proxy settings.


marius roma
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[MERGED] Hotadd Vs. Direct Access

Post by marius roma » Nov 14, 2016 12:17 pm

Imagine 3 proxies hosted by a vSphere cluster backing up VMs hosted by datastores on LUNs accessed via iSCSI on a 10Gbit LAN.
Is it advisable to use Direct Access, letting the VMs directrly access the LUNs via iSCSI or Virtual Appliance (hotadd) mode?
Which are possible advantages and problems?

Veeam Software
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Re: Hotadd Vs. Direct Access

Post by foggy » Nov 14, 2016 1:01 pm

You can test both to check which one is better in your particular environment. If you have 10GB everywhere, I'd also check network mode, since its performance on a fast LAN can be comparable to other modes.

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