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jelockwood

Retrospect CPU limits under Sierra cause massive slowness

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Retrospect ever since version 8 and still all the way to version 13.5 i.e. the very latest has been utterly insane regarding the amount of CPU power it uses.

 

Retrospect is not a rendering program, it is not trying to calculate million digit prime numbers, it is a poxy backup program!!! There is no way it should need such massive amounts of CPU power, other brands of backup program do not. Previously Retrospect have come up with the absurd response that they are 'reserving' CPU i.e. grabbing 100% of a single core whether they need it or not. This is not how programs work, CPU usage is not like memory usage, yes for memory you do often need to pre-allocate a block of RAM but for CPU you use it or you do not use it, you do not allocate it regardless.

 

Note: I have previously turned off every possible option like software compression, encryption, de-duplication, etc. etc. which made no difference.

 

Now today whilst I am still very disappointed by Retrospect's continuing pathetic CPU utilisation problem I am reporting a new problem which appears to be a direct result of Retrospect being so bad with regards to CPU usage. We recently upgraded one of our servers to Sierra 10.12.3 from a previous generation of OS X. The Mac is the same model using the same drives with the same files on the same external data drive as before being upgraded, Retrospect has correctly spotted the files are the same so is not doing a backup of all files only the changed ones. One would expect the backup to take a similar amount of time as before the client i.e. the Mac server was upgraded. In fact technically speaking it seems the backup is taking a similar amount of time but what is taking hours and hours longer is the post-backup cataloging and snapshot making tasks.

 

We have had a look at the Console logs on this Mac server and found that there are entries like the following

 

Date/Time:       2017-03-01 08:10:39 +0000

OS Version:      Mac OS X 10.12.3 (Build 16D32)

Architecture:    x86_64

Report Version:  19

 

Command:         RetrospectInstantScan

Path:            /Library/Application Support/Retrospect/RetrospectInstantScan.bundle/Contents/MacOS/RetrospectInstantScan

Version:         13.5.0 (173) (13.5.0.173)

Parent:          launchd [1]

PID:             25918

 

Event:           cpu usage

CPU:             90s cpu time over 114 seconds (79% cpu average), exceeding limit of 50% cpu over 180 seconds

Duration:        114.21s

Steps:           130

 

Hardware model:  Macmini7,1

Active cpus:     4

 

Fan speed:       1794 rpm

 

This is showing that Sierra has spotted excessive CPU usage by RetrospectInstantScan and the implication is that when this happens Sierra throttles the CPU usage of this process which would slow it down and then slow down the Retrospect backup.

 

Note: We also saw a similar message for the RetroClient process as below

 

Date/Time:       2017-02-26 13:11:08 +0000

OS Version:      Mac OS X 10.12.3 (Build 16D32)
Architecture:    x86_64
Report Version:  19
 
Command:         retroclient
Path:            /Library/PreferencePanes/Retrospect Client.prefPane/Contents/MacOS/retroclient
Version:         ??? (???)
Parent:          launchd [1]
PID:             62
 
Event:           cpu usage
CPU:             90s cpu time over 123 seconds (73% cpu average), exceeding limit of 50% cpu over 180 seconds
Duration:        123.28s
Steps:           107
 
Hardware model:  Macmini7,1
Active cpus:     4
 
Fan speed:       1794 rpm

 

Although this one surprisingly is not logged for every day.

 

These logs are located in /Library/Logs/DiagnosticReports/

 

Note: These particular logs are not created on a virtually identical El Capitan server and those El Capitan servers have not exhibited this new problem although as mentioned like all Macs running Retrospect server or client use excessive CPU power all the time a Retrospect task is active.

 

It seems it is possible to disable Sierra's CPU throttling mechanism but that this is not an easy process.

 

See http://apple.stackexchange.com/questions/254143/how-do-i-disable-configure-macos-sierras-auto-throttling-of-the-cpu-for-process

 

Once again I stress the problem is Retrospect's long time and still present pathetically poor CPU utilisation. (We will ignore the fact Retrospect is also almost completely incapable of using multiple CPU cores for a single backup script even though logically many tasks could be overlapped or distributed e.g. compression, encryption, cataloging.)

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