Jump to content
Sign in to follow this  
dittberner@dbr3.de

How fast are your network backups?

Recommended Posts

Hello,

we are testing the new Retrospect 14.5 on mac as new server backup solution. 
Our plan is to use Retrospect Multiserver on MacPro with 10.12.6 and 10GBit network connection to backup data from Hyper-V Windows 2012r2 virtual machines which are also connected via 10GBit ethernet.
Data and backup sets are on FC Raids (8GBit). If we connect to vm from MacPro via Windows smb share, we get a speed up to 700MByte per second read and write.
 
Our first tests with Retrospect results in network speeds of max 4GB/min (backup and copy) which seems to be much slower than 700MB/s.
 
Do you reach faster network speeds? Did we something wrong?
 
Have a nice day
Kai
 

Share this post


Link to post
Share on other sites

2.5 years of experience using Retrospect Mac on my home LAN shows that the main factor limiting speed of networks is the traversal of multiple files in the file system by the client computer.  This morning I got a speed of 400MB/min doing a Normal backup of my MacBook Pro client, but yesterday I got a speed of 600MB/min doing the same Normal backup—but of somewhat different files.  Last Saturday I did a Recycle backup of the same MacBook Pro, and got a speed (for 36GB over 3 hours) of 200MB/min; my Recycle backups are of everything including cache files.  All these speeds are for backup only; I've omitted the speeds of compares.

 

About 6 months ago I had to replace the hard disk drive on my MacBook Pro with an SSD; the backup speeds did not appreciably increase.  I therefore conclude that the controlling factor in Retrospect traversal of multiple files is the speed of the client computer's processor(s).  It's possible that the speed-limiting file traversal is on the "backup server" side (but see the P.S. below for why I think that unlikely), but my "backup server" for the last 2.5 years has been a 6-processor 2.5 GHz 2010 Mac Pro—with the same USB3 portable drives for my Media Sets.

 

As for LAN speed, my limiting factor is the built-into-the-wall inter-room RG-59  cable between my MacBook Pro and my Mac Pro, which has Actiontec MoCA adapters on each end.  The MoCA adapters I have are limited to 270Mbps "raw" = about 1600MB/min "cooked" (I assume 10 bits/byte to allow for 20% TCP/IP overhead).  That's obviously a lot faster than the backup speeds I'm getting, which never seem to go much above 600MB/min on an instantaneous basis.  The Cat5 cable between my bedroom MoCA adapter and my Mac Pro might in fact be limited to 100Mbps by the fact that it was attached around 3 sides of the bedroom wall in 1998 by a local contractor using—fairly carefully—metal brads he had brought with him (he didn't know he was going to have to string Cat5 cable along walls), but I'm not about to buy and string new Cat5e cable (especially since on one occasion I did a bypass by running a Cat5 cable directly from the MoCA adapter to the Mac Pro, and it didn't speed up the backup).  I could buy replacement gigabit MoCA adapters for a total of US$150, but I'm reluctant to spend the money since I'm not sure they would make much of a difference.

 

dittberner may want to read this 2013 thread, in which post #2 by the very-knowledgeable Lennart Thelander shows speed results rather similar to mine.

 

P.S.: I knew there was a further reason that I ruled out file traversal on the "backup server" as the speed-limiting factor, and I have now remembered what it was.  Back in June 2015, before I spent a substantial amount of money upgrading my (inherited from a dead friend) Mac Pro's hardware and software to be my "backup server", I ran a feasibility test using the hardware and software I already owned.  I ran a Recycle backup of my MacBook Pro using my ex-wife's 733MHz Digital Audio G4 as the "backup server", SCSI-cabled to my old DAT tape drive for a Backup Set (the old term for Media Set), and running my old copy of Retrospect Mac 6.1.  The backup part of the test ran at 170MB/min, which is almost as fast as the 200MB/min in last Saturday's Recycle backup of my MacBook Pro—which used a 2.5GHz Mac Pro as the "backup server" hardware and Retrospect Mac 14.0 as the "backup server" software.  The test was run over the same LAN I have now, except that my Ethernet switches were then only 100Mbps instead of 1gigabit/sec.

Edited by DavidHertzberg
Added parenthetical ref. to P.S. in 2nd prgf., added current switch speed to that P.S.

Share this post


Link to post
Share on other sites

Rereading dittberner's OP just now, I realized I had misread what he/she is trying to do.  His/her virtual machines are not Retrospect clients connected to the "backup server" over TCP/IP, but are instead connected to the "backup server" as SMB shares.

Thus his/her situation is closer to what I did today when I ran my Recycle backups of all 6 drives, including 2 drives that are local to my Mac Pro "backup server"—they are inside the "cheesegrater" Mac Pro' s case connected by SATA.  For those two drives, the combined backup-compare speeds were 2.423GB/minute and 1.425GB/minute respectively.  Considering that according to this Wikipedia article SMB evidently has more overhead than SATA, 4GB/minute seems quite reasonable for Retrospect combined backup-compare speeds on what is almost certainly a faster machine than my 2010 Mac Pro.

Note that my first local drive has more data, but fewer files and folders, than my second local drive.  Therefore what I said in the first paragraph of the second post in this thread should still apply in a slightly-revised formulation; traversal of multiple files (and folders) on the Source drive—on whatever computer the Source drive is attached to—seems to be the factor that limits the speed of backups.

 

Share this post


Link to post
Share on other sites

Hello David, 

sorry for the late reply.

We use the Retrospect Client on the backup client machine. The smb speed is only for a comparison.

We have similar speeds with 1GBit ethernet like you. We need to get more speed and upgrade to 10GBit ethernet, not only for the backup of course. But it seems, that Retrospect can't benefit from the faster network as we like. Our latest test comes near to 6GB per Minute which are 100MB per second. And I think it should be more possible with all this hardware. Maybe there is a software limit in Retrospect.

Kai

 

 

 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×