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Netbackup Accelerator Forced Rescan is running very slowly

Level 2

Hi Netbackup Experts,

I have configured Netbackup Accelerator for a windows file server. 

I have configured to run full backup with accelerator forced rescan once in a month. When it runs, the progress is very very slow. Is there any way to speed it up?


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It's supposed to be slow, it is basically doing the "first" backup again. That means, there is no acceleration, it's doing everything from scratch.



As @RiaanBadenhorst replied it is normal to be slower than the "regular" backup (with the accelerator of course)

Veritas recommends to configure a schedule with the option forced rescan every 3-4 months.. (once a month is ok too but I personally recommend to do it every 3-4 months to benefit from accelerator.



First of all I had to cancel the Accelerator Forced Rescan (AFR) full backup since it's running in 2 MB/sec and it's been running for 6 days which is ridiculous. I was thinking may be it's taking time to do some calculation at the back end and anytime the backup speed would gear up. No it didn't happen.

Now I am running an incremental to backup the changed data in last 6 days.

Even if AFR backup is supposed to behave like 1st backup, it should be fast.

I have observed an interesting matter:

1. After AFR backup kicked in, I found the progerss to be little. So I started monitoring in the Resource Monitor. Multiple threads are running in the system.But one thread at a time is reading the filesystem and updating 500 files. Then no bpbkar32 process is reading filesystem for 20-40 seconds and then another thread start reading filesystem. I know it's ridiculous. But that's the count I saw in the Netbackup console and the bpbkar32 behaviour in resource monitor window. The speed of reading filesystem was below 1 MB/sec mostly.

2. When I am running incremental backup, same multiple threads are running. But the overall filesysteam reading speed is 50-70 MB/sec as I am observing in resource monitor.

Why does Netbackup behave in this manner? 


Can you please confirm how many files are you backing up?? Do you see millions of very small files being backed up and do they change (small files) every day or frequently??

Share the job details showing the number of files you are backing up. I have seen Accelerator backup taking more time compared to incremental or differential backup when there are millions or multiple thousands for very small size files to backup.

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Accelerated forced rescan is ensentially like performing brand new backup for the very 1st time. It is bound to be much slower if there are lots of millions small small files. Examine the total size of data to be backed up, network speed, cpu usage e.t.c