DPM Backup of Cluster Shared Volumes Starwind VSS Provider

[hixont]

If only we weren't so demanding about performance, functionality and reliability.

I'm considering using a combination of CSV and non-CSVs to resolve this issue on my end. The few DPM need servers I have will live on the non-CSV(s) and the rest on the CSVs. This way I still get the DR snapshot recovery capabilities provided (in the future) from StarWind and I can do brick level backup and restores via DPM (hopefully) without the huge performance hit. At least that's my current thinking before field testing this configuration.

[Anatoly (staff)]

Well, sounds like a plan:)
Just doublecheck if all of your software is up to date. Here is the link to download the latest StarWind build.

[jeffhamm]

An update since we've been using DPM 2010 to backup the at the VM level using the software VSS provider for some time now. The good news is that after the backup completes, the Software VSS provider does release the reservation, and the CSV volume exits Redirected Mode and goes back to "direct access" mode for the other HyperV cluster members. We have had zero issues with the CSV volume getting stuck in Redirected mode.

The bad news is that the there is a definite performance hit during the backup window while the CSV volume is in redirected mode; I need to run some more tests to quantify this.

Question - is the Hardware VSS provider still in the works or available as a beta? This would obviously solve the issue with the CSV volumes being forced into Redirected Mode for the entire duration of the backup.

Thanks,
Jeff

[anton (staff)]

Hardware VSS should be published Gold with V5.8 release so you may test it right now.

An update since we've been using DPM 2010 to backup the at the VM level using the software VSS provider for some time now. The good news is that after the backup completes, the Software VSS provider does release the reservation, and the CSV volume exits Redirected Mode and goes back to "direct access" mode for the other HyperV cluster members. We have had zero issues with the CSV volume getting stuck in Redirected mode.

The bad news is that the there is a definite performance hit during the backup window while the CSV volume is in redirected mode; I need to run some more tests to quantify this.

Question - is the Hardware VSS provider still in the works or available as a beta? This would obviously solve the issue with the CSV volumes being forced into Redirected Mode for the entire duration of the backup.

Thanks,
Jeff

[jeffhamm]

Thanks Anton, 2 more quick questions:

1) Is the Hardware VSS provider a separate installer that you run directly on your HyperV Hosts?

2) I assume that the hardware VSS provider requires V 5.8, or does it also work with 5.7?

Thanks,
Jeff

[anton (staff)]

1) You'll have to run Hardware VSS where you connect to StarWind *FROM*.

2) Sure. It's not provider itself added, it's the whole stack altered.

Thanks Anton, 2 more quick questions:

1) Is the Hardware VSS provider a separate installer that you run directly on your HyperV Hosts?

2) I assume that the hardware VSS provider requires V 5.8, or does it also work with 5.7?

Thanks,
Jeff

[edmondegan]

Hi Anton,

Just looking at downloading 5.8 and noticed the description for the vss provider was

StarWind VSS Provider
This installer contains VSS Hardware Provider and VSS Software Provider for Deduplication and CDP devices.
These providers guarantee snapshot consistency if installed on a client system:

I thought the hardware vss provider was an internal part of 5.8 rather than the additional provider ?

Could you clarify this possibly ?

[anton (staff)]

VSS providers (does not matter software or hardware) run @ initiator (client) side rather then @ target (server). They do however require mods applied to target to wrap actual VSS calls into target architecture-dependent sequence of actions.

Hi Anton,

Just looking at downloading 5.8 and noticed the description for the vss provider was

StarWind VSS Provider
This installer contains VSS Hardware Provider and VSS Software Provider for Deduplication and CDP devices.
These providers guarantee snapshot consistency if installed on a client system:

I thought the hardware vss provider was an internal part of 5.8 rather than the additional provider ?

Could you clarify this possibly ?

[edmondegan]

Just speaking to support re: this but can we get confirmation if 3rd party snapshots are supported by the starwind hardware vss provider as I thought this was the case with 5.8 i.e. people with dpm or backupexec would benefit from no redirected io in hyper-v using csv.

[anton (staff)]

The whole thing works very different from you expecting it to work. In a nutshell:

1) VSS-aware application (already referenced Symantec [Veritas] BackupExec or Microsoft DPM or for example VEEAM Backup or our own homebrewed Hyper-V Backup) requests VSS layer to create a snapshot for some physical or logical volume.

2) VSS layer (provided entirely by Microsoft) scans list of registered software and hardware VSS providers for this volume. If none is found volume is picked up by default Microsoft software VSS provider. With all the drawbacks - redirected I/O for Hyper-V, slowed down I/O b/c of COW used and 4-requests-instead-of-1, wasted reserved disk space for shadow copy etc. That's what we have for "el cheapo" software and hardware targets w/o VSS provider shipped with.

3) If VSS layer finds a software or hardware VSS provider (our case) provider - it becomes responsible for snapshot action taking. In our case it just signals array firmware (StarWind iSCSI SAN core) to turn a snapshot to another one. We really need to ship both software and hardware providers b/c only hardware could be used by Hyper-V and only software could be used by non-server OS (utter architectural nonsense, they should and are nearly 100% identical for us and most of the vendors I know).

So... No "3rd party snapshots" can work with StarWind (or any other on Earth) VSS provider as snapshot engine (like for example StorageCraft ShadowProtect) has to have own matching VSS provider. From the other point of view any properly written VSS-aware application should deal with StarWind snapshots thru StarWind VSS provieder. Just b/c it has no clue about StarWind presence (and any other VSS provider presence) and deals directly with Microsoft VSS asking to prepare and create a snapshot for particular volume.

Is it a little bit more clear now?

Just speaking to support re: this but can we get confirmation if 3rd party snapshots are supported by the starwind hardware vss provider as I thought this was the case with 5.8 i.e. people with dpm or backupexec would benefit from no redirected io in hyper-v using csv.

[rafelmarken]

According to my view, When System Center Data Protection Manager is protecting Hyper-V guests using the Microsoft Software Shadow Copy provider (the VSS provider), DPM will be using software snapshots when backing up guests located on Cluster Shared Volume (CSV) disks. While the backup is in progress, the CSV will remain in re-directed access mode for the duration of the guest backup.

[anton (staff)]

Yes, unless you have properly configured and recognized hardware VSS provider.