Artificial Limit on Backup Speed to SSD

What "segment" are you referring to? Are you using a PC with an older motherboard using a Bus channel for data? Just because your SSD's are capable of 300MB/s doesn't necessarily mean you will achieve those speeds. Other hardware can limit data transfer rate. Are both these drives internally mounted?

Segment was probably not the correct term. I found some XML option files in an Acronis directory. The file seems to be updated when Acronis finds or finishes a new backup. It appears to list the settings for the backup. The XML text didn't make it into my post and I didn't notice. Here it is with the brackets changed to parentheses: (disk_speed_limit speed_limit_mode="absolute" value="99999"). I have also attached the file (zipped).

All of the option files have this limit listed near the network speed limit. Unlike the network speed limit, I don't see anywhere in the UI to set the disk speed limit. The presence of this text seems like an indicator that the software has the ability to limit the disk speed and that the default limit is 99999. If the units are KB/s, that would be very close to what I am seeing.

Both drives are internal, running at 6Gb/s SATA speed, and tested for sustained writing throughput in excess of 350MB/s. The source is an 840 Pro and the destination is an 840 Evo. I run my testing for long enough to eliminate caching effects (>100GB of writing). The 840 Evo in my machine settles to about 370MB/s which is consistent with other benchmarks found around the internet.

At maximum compression, the cpu becomes the limit with the destination being written at <60MB/s. At high compression, the cpu is near 100% and the destination drive is accessed at very close to 100MB/s. At normal compression and no compression, the cpu is <40% and the destination drive is limited to a very steady 100MB/s (less than 2MB/s variation over 20 minutes). It seems very clear that something in the Acronis software is limiting the destination writing speed to approximately 100MB/s. I can even watch the source reading speed change as the compressibility of the source material changes, but the destination speed is pinned near 100MB/s.

I have also tried backing up a different SSD to an external drive capable of sustained writes of about 125MB/s. I see the same ~100MB/s destination limit on this drive.

I just figured out how to remove the limit. There is another directory with the backup script files. The destination writing limit is set in those files to ~100MB/s. I can more than triple my backup speed by raising it to 500MB/s. It also looks like setting the limit to 0 has the effect of removing the limit.

I think that Acronis should change the default to no limit.

Well, nice find. I would comment however that this imposed limit is there because of something you sort of eluded to above, that being, drives capable of sustained writes around the 120MB/s limit and other hardware that is limited in the transfer of data such as the older generation of motherboards with a system bus not capable of sustaining high transfer rates (yes there are still some of those out there in use) as well as those with less hardware such as lower RAM memory installed that play into the picture. Acronis as well as all other developers must consider these Legacy systems when releasing products to market as the installed user base is very wide. Not all users have the latest and greatest hardware and a good amount do not even come close to that so, a middle of the road approach with realistic maximums must be adopted. This one size fits all approach to some, such as yourself, will find this as a flaw. Understandable but, never the less appropriate given the circumstances.

I am curious, how much memory do you have installed on your system and what does memory usage look like during these observed tests? I think there might be some concern, although probably minimal, with data loss at high memory usage and high data transfer rate. To be on the safe side you might consider running several test backup jobs and insure the backups are valid and can be restored before going to far with this.

I think you are implying that it is risky to use the full capability of my hardware. If that is the correct, I disagree. The software is broken if it isn't designed to function properly in the case that it is limited by speed of the destination. I don't have any indication that this Acronis software is broken in that way and it behaves properly against the artificial limit or the natural limit of the drive.

If I were worried about my hardware doing something wrong when fully utilized, I would get different hardware. No properly working system should be at risk of failing when pushed to the stock operating limits.

There is no concerning memory usage trend in any of the scenarios I have described. True Image behaves as I would expect of quality software. I can back up from a very slow source to my very fast drive and the source becomes the limit. I can back up from a fast source to a slow drive or an artificially limited drive and the destination or software becomes the limit. The memory usage doesn't change dramatically at either extreme.

Maybe the 99999 was put in when drives weren't that fast and it didn't seem like it would be an artificial limit. I would be very concerned about the quality of the software if it was put in to mask some other problem. Do you know why the default is set to 99999 (source control comment)? Do you know about a flaw in the software that gives you a different opinion?

I'm not sure you want to imply that there may be an increased risk of data loss at high memory usage and high data transfer rate. Properly designed software wouldn't let that happen without warning and notification. I think your statement implies some kind of defect in the software.

I still think that Acronis should remove the limit by default, or at least expose the setting in the user interface next to the network speed limit. I don't really want to edit those scripts each time I create a new job.

Not implying risk of data loss due to high memory usage nor am I implying that there is a flaw in the software. My reference to memory is simply that there is always a risk of some data loss in consumer grade non ECC RAM. This risk is minimal as I stated. If non ECC RAM is pushed to high limits this may increase the risk of data loss, not saying it will just that it may be possible. My statement only implies that it may be prudent to test higher data transfer speeds to insure that data can be transferred at these higher limits without any loss resulting in corrupted backups. If you are willing to forge ahead without such testing that choice is yours. I think it obvious that the Acronis engineers have some concern in placing such a limit in the software design. If not and as you say it is a leftover from days gone by then yes, I would agree that the limit be removed. I have no proof or knowledge of that so until it is reported otherwise I suspect the built in limit you have discovered will remain.

What would be the proper way to report this issue? I would like to see it changed, but I don't know how to ask. My official service period has expired.

Thanks,
Jason

There is a feedback link on the support page, not sure how much traction you would get but is one way of putting the issue before Acronis.

This sounds like a sticky or Grover's archive of tips if I ever saw one.

It is still working great for me!

I haven't upgraded to 2015 yet. Does anyone know if it is changed/fixed yet?

Comment, this so called "artificial limit to back up speed" is in all likelihood a limitation by design more than it is an artificial limit. You must consider that the software needs to function and function well on countless different hardware configurations including externally attached devices of a number of arrangements. Modern HDD's are capable of sustained data transfer of around 145MBps when used in a fairly new machine. This same drive in a bit older machine would only be capable of transfer of around 120MBps at best. The same drive used in a network arrangement would be limited even further. The limit discussed herein is in my opinion an acceptable trade off so that the app will perform well on as many different hardware setups as possible. I doubt this will change anytime soon.

JLMart,
Is this a disk image backup or partition type backup or a files/folder backup script?

Would you mind posting an example of a before and after change of the script?

Here is how to do it:

I'm not sure why you say "in all likelihood". We discussed this earlier and I think my supposition is as good as yours.

I think the limit is artificial and unnecessary even in the case of old and/or slow hardware. If you have a slow piece of hardware, the Acronis software does the right thing and runs at the speed of the slowest component. It doesn't just fail or start to perform poorly. The software would be faulty if it needed the limit to ensure proper function across a broad range of hardware. I don't think the software is faulty in that way.

Given that the software works properly with slow hardware on either end and the limit removed (I have demonstrated that it does), why do you think it is reasonable to leave the limit in place? Also, why 99,999KB/s and not 50MB/s or 200MB/s or 10MB/s? What makes 99,999KB/s the magic number?

I think that the best solution would be to treat it exactly like the network limit. Default to no limit and allow an advanced user to set a limit if they have some reason to do so.

Mine are partition images, but I don't think that matters.

Billybigun's document tells you how to do it.

Current default values for these settings. These are extracts from actual script files from within a stored backup.
disk image backup to both internal & external disk.

2015
net_speed_limit speed_limit_mode="absolute" value="0"
disk_speed_limit speed_limit_mode="absolute" value="0"

2014
net_speed_limit speed_limit_mode="absolute" value="0"
disk_speed_limit speed_limit_mode="absolute" value="99999"

2013
net_speed_limit speed_limit_mode="absolute" value="0"
disk_speed_limit speed_limit_mode="absolute" value="99999"

Excellent! Thanks for the update. I guess I won't have to worry about it after I update to 2015.

For the record, I also disagree with Enchantech's assertion that there is a reasonable excuse for imposing a limit to the disk transfer rate. Given that a typical spinning drive cannot reach even 80MB/s sustained write speeds (I'm talking about the "green" 5400 crap that vendors put in budget systems) if the cap were necessary it should be a lot lower than 100.
The fact is, the hardware will go as fast as the slowest part can, and function just fine while doing that ... cap or no cap.