Discussions specific to the Microsoft Hyper-V hypervisor
Post Reply
AlexLeadingEdge
Expert
Posts: 263
Liked: 29 times
Joined: Dec 14, 2015 9:42 pm
Contact:

Backups too fast (600 MB/s)

Post by AlexLeadingEdge » May 06, 2018 10:21 pm

Hi guys,

I'm seeing really weird numbers in our backup times which have me worried...

7/05/2018 10:02:53 a.m. :: Hard disk 1 (127.0 GB) 24.0 GB read at 481 MB/s (sent in 55 seconds)
7/05/2018 10:03:57 a.m. :: Hard disk 2 (200.0 GB) 12.0 GB read at 600 MB/s (sent in 3 minutes and 19 seconds)
7/05/2018 10:09:22 a.m. :: Hard disk 1 (127.0 GB) 98.9 GB read at 542 MB/s ( sent in 3 minutes and 10 seconds)
7/05/2018 10:13:59 a.m. :: Hard disk 1 (50.0 GB) 38.1 GB read at 413 MB/s ( sent in 1 minute and 36 seconds)

This isn't physically possible for the drives to read this fast, and definitely not possible to send that much data (24 GB in 55 seconds) across a simple Ethernet network. Is this some sort of metadata speed calculation that includes things like compression and white space? What is the point of these kinds of statistics?

foggy
Veeam Software
Posts: 17097
Liked: 1397 times
Joined: Jul 11, 2011 10:22 am
Full Name: Alexander Fogelson
Contact:

Re: Backups too fast (600 MB/s)

Post by foggy » May 07, 2018 3:50 pm

Is this an incremental job run?

AlexLeadingEdge
Expert
Posts: 263
Liked: 29 times
Joined: Dec 14, 2015 9:42 pm
Contact:

Re: Backups too fast (600 MB/s)

Post by AlexLeadingEdge » May 09, 2018 8:45 pm

Yes.

foggy
Veeam Software
Posts: 17097
Liked: 1397 times
Joined: Jul 11, 2011 10:22 am
Full Name: Alexander Fogelson
Contact:

Re: Backups too fast (600 MB/s)

Post by foggy » May 14, 2018 5:08 pm

Incremental runs are always significantly faster because they need to process only a few changed blocks, not the entire VMDK.

AlexLeadingEdge
Expert
Posts: 263
Liked: 29 times
Joined: Dec 14, 2015 9:42 pm
Contact:

Re: Backups too fast (600 MB/s)

Post by AlexLeadingEdge » Jun 08, 2018 12:10 am

So even though it says "98.9 GB read" it is only doing the changed blocks for that 98.9 GB? No wonder the speed calculation is absurd!

Perhaps Veeam B&R could start using actual data transferred divided by the time to give the actual speed?

foggy
Veeam Software
Posts: 17097
Liked: 1397 times
Joined: Jul 11, 2011 10:22 am
Full Name: Alexander Fogelson
Contact:

Re: Backups too fast (600 MB/s)

Post by foggy » Jun 08, 2018 1:48 pm

This is not the transfer speed, but the speed of reading (processing) disk data. Transfer speed is calculated from the actually sent data.

AlexLeadingEdge
Expert
Posts: 263
Liked: 29 times
Joined: Dec 14, 2015 9:42 pm
Contact:

Re: Backups too fast (600 MB/s)

Post by AlexLeadingEdge » Jun 11, 2018 1:52 am

Ok, so just to recap...
98.9 GB read at 542 MB/s ( sent in 3 minutes and 10 seconds)
Am I correct in saying:
- B&R didn't actually read 98.9GB, it only read the changed blocks of that 98.9GB.
- B&R didn't actually read all 98.9GB at 542 MB/s, it read the changed blocks of that 98.9GB at 542MB/s.
- B&R didn't actually send 98.9 GB in 3 minutes and 10 seconds, it sent the changed blocks in 3 minutes and 10 seconds.

foggy
Veeam Software
Posts: 17097
Liked: 1397 times
Joined: Jul 11, 2011 10:22 am
Full Name: Alexander Fogelson
Contact:

Re: Backups too fast (600 MB/s)

Post by foggy » Aug 22, 2018 4:53 pm

AlexLeadingEdge wrote:- B&R didn't actually read 98.9GB, it only read the changed blocks of that 98.9GB.
Correct.
AlexLeadingEdge wrote:- B&R didn't actually read all 98.9GB at 542 MB/s, it read the changed blocks of that 98.9GB at 542MB/s.
Not at 542MB/s, but at some actual speed. 542MB/s is calculated from the entire 98.9GB of "processed" disk data, most of which is simply skipped.
AlexLeadingEdge wrote:- B&R didn't actually send 98.9 GB in 3 minutes and 10 seconds, it sent the changed blocks in 3 minutes and 10 seconds.
Correct.

RoyAyres
Lurker
Posts: 1
Liked: 2 times
Joined: Jan 12, 2018 4:37 pm
Full Name: Andy Davies
Contact:

Re: Backups too fast (600 MB/s)

Post by RoyAyres » Sep 03, 2018 2:31 pm 2 people like this post

I wish I had this problem!

Post Reply

Who is online

Users browsing this forum: Exabot [Bot] and 9 guests