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some vmware restore to are slow

Hello Team, 

Haven't been here for a while. But I have an issue with restores. 
All is on Netbackup 8.1.2, 
Master is a remote VM on windows 2016. 
The Media server is local, this is an Veritas Appliance 5240. 
I am restoring to a VMware VSAN. Some restores go fast, I see speeds between 40 and 80MB/s. But some other restores go slow. There is one which needs 700Gb, there I see speeds like between 200kb/s and 80MB/s. I am using MSDP. To see if it was caused by the hydratation of the data I made an advanced diskpool to backup the same VM and then I restored it again from this backup. That made no difference.  

I have the activity log attached of the slow backup, I see a lot messages like "waited for empty buffer 7042 times, delayed 7270 times" but I see those also at the fast restores. The fast restores have a constant speed and the slow one has a very various speeds. 

Any Ideas? 

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4 Replies

Re: some vmware restore to are slow

somehow I cannot attach a TXT file. What should I do? 

Re: some vmware restore to are slow

@RobDullaart wrote:

somehow I cannot attach a TXT file. What should I do? 

We will need a VOX Admin to investigate. 


Could you please check and advise? 

Re: some vmware restore to are slow

You have mentioned restore to VSAN volumes - can we assume that you are using NBD or NBDSSL transport mode to backup and restore?

Have you tried to find out from VMWare admin what is different w.r.t. ESX resources between the fast and slow restores?

I found this fairly old TN with possible reasons for slow restores:
* Due to a limitation in the APIs in VMware's Virtual Disk Development Kit (VDDK), the write performance during virtual machine restore does not use the maximum bandwidth of the underlying hardware and therefore may not match the read speed.
* VMware APIs cannot perform simultaneous writes to the same datastore from multiple restore jobs. 
For better performance, do not run simultaneous restore jobs to the same datastore.

Another TN about slow restore to thin provisioned volumes:

Also have a look at the "Best Practices when using LAN" section of this TN:

Re: some vmware restore to are slow

Hi @RobDullaart , (and thank you for tagging me @Marianne )

Apologies - it was a holiday in the US on Friday.

Are you still having trouble attaching your .txt file to this post? I did a test, and .txt is supported in the VOX community discussions. Please let me know what browser you are using, and I will investigate further with our platform provider.

Many thanks,