The bottleneck between CPU and HDD/SSD destination drive when using different compression level.
BACKSTORY
I bought a SSD few days ago and posted it on reddit, said that I’m going to use it for backups, and then an Acronis Community Manager kindly asked me about the performance of the backup operations. So, let’s do some test, to see the bottleneck between CPU and different destination drives.
PC SPEC
AMD Ryzen™ Threadripper™ 1950X @ 4Ghz
G.Skill Trident Z RGB DDR4 3200Mhz CL14 16GBx4 @ 3066Mhz 14-14-14-28
Intel® Optane™ SSD 900P 280GB (Source drive)
Intel® SSD DC S4500 3.84TB (Destination drive)
TOSHIBA DT01ACA300 3TB (Destination drive)
METHOD
To capture the elapsed time of a backup operation, I wrote this batch script which simply output the current system time to a text file. By putting this script into the Pre/Post Commands section of the task, it will be auto-executed by Acronis True Image before and after the backup operation.
echo %time% >> Z:\script\time.txt
There will be eight parts to this test, all of them will backup the Windows from the source drive, to different destination drive using different compression level respectively:
- Source -> SSD, Compression None
- Source -> SSD, Compression Normal
- Source -> SSD, Compression High
- Source -> SSD, Compression Max
- Source -> HDD, Compression None
- Source -> HDD, Compression Normal
- Source -> HDD, Compression High
- Source -> HDD, Compression Max
DATA
Here’s a full video of the data capturing process, this include real time CPU usage and disk load graphs, I don’t have suitable software to make those into text data, sorry about that.
ANALYSIS
The backup operation speed goes up when increasing the compression level from None to High. When compression level is High and destination is SSD, the CPU usage is about 70% and source drive full load all the time. So, High compression level is the ideal setting for my PC because if I use Max compression level, I only save 1% more space with the cost of 44.6% speed decrease.
As for HDD, same situation happens, High compression level is also the ideal setting, Max compression level caused 14% speed decrease.
But, there’s something different from my expectation. I was expecting once the CPU bottlenecks and the compression speed drops below the HDD’s maximum writing speed (about 200MB/s), there will be no difference between using HDD or SSD as destination. But the data shows that even at maximum compression, CPU full load and compression speed drops dramatically, the SSD is still 17% faster creating the backup.
CONCLUSION
Using SSD as your backups’ home is a good idea if you own some high endurance model, or if your data is small, you can have pretty good speed creating backups. And think before using Max compression unless you are very short of space, depending on your CPU speed, choose between Normal and High.
And sorry for my bad English.
Peter,
Your test results are comparable to my own results. Personally I stick with Normal compression as I don't see enough advantage of using the High setting in my environment. Your results prove that out as well (not enough difference).
Thanks for posting your results.