This seems to be a question often asked, but not clearly answered : how long will it take to sync an array? Unfortunately, without some guideance, it is difficult to choose between Snapraid and other options.
Would a specific example help? Assume 4x4TB HDDs, one for parity. Assume each data drive has 2gb of data. Assume that each day 50 GB is added to each data drive (150 GB total new data). How long would it take to sync the array?
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I used to use Flexraid, which took 4 days to build my 80TB array, snapraid does this in around 26hrs, add to that flexraid had serious memory leaks that were not fixed when i stopped using the product, and snapraid just works.
To me the speed of snapraid is the absolute best thing
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Looking at my last log: I added 50GB, sync took 22 minutes. This is with 6 data discs, 2 parity, all 7200 rpm.
Time should be proportionate to the amount of new data, but the distribution of content on the data discs will matter. If one disc is being filled and the others are empty past a certain level, I presume the sync runs faster.
-Bill
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If one disc is being filled and the others are empty past a certain level, I presume the sync runs faster.
The opposite, actually. If you add 10GB to one of 10 data drives, SnapRAID has to read and process 100GB (10GBx10 drives). If you added 10 GB across each 10 drives, 1 GB per drive, SnapRAID only has to read 10GB (1GBx10 drives). This is vast oversimplification and doesn't account for many other factors, but it should demonstrate why spreading out data typically results in faster syncs.
Last edit: Quaraxkad 2015-11-21
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This is not a question that anybody can answer for you, which is why it's not clearly answered! There are too many variables, you'll just have to run it yourself to see how long it takes. It's affected by the speed of the drives, the number of drives, the ability of your hardware and controller cards to handle simultaenous reading and writing to multiple devices, the number of files on the drives, the amount of data on the drives, the speed of the processor and memory, etc. There's absolutely no way to estimate how long your sync will take.
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True, however,i run snapraid on 3 different boxes,all with different hardware,ranging from IBM1015m IT mode SATA controllers with WD40EFRX to an old gigabyte uhd-55 motherboard using on board sata controllers with old 500GB-1TB WD and Seagate drives, and ranging in size array from 80TB on my home media storage server,to my 12TB home video,vacation photos and all manner of backups,and ALL run smooth and fast with snapraid.
I just tried flexraid again today,and i could not get read speed past 12mb/s and snapraid on same box runs at 70mb/s HUGE difference..
I am currently running a new parity on my home media server, with read speeds of 110MB/s, flexraid again never get past the 18MB/s read speed on this box.
Also, the ETA reported from snapraid is quite accurate, where as flexraid, you can never tell if program has crashed or stopped as there is no progress indicator,and this is extremely annoying.
Add to that the new low memory use, it is an absolute winner.
Only thing i would like is a gui with email reporting and initial setup,as commandline can be daunting to a lot of people.
Last edit: Benny King 2015-11-21
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This seems to be a question often asked, but not clearly answered : how long will it take to sync an array? Unfortunately, without some guideance, it is difficult to choose between Snapraid and other options.
Would a specific example help? Assume 4x4TB HDDs, one for parity. Assume each data drive has 2gb of data. Assume that each day 50 GB is added to each data drive (150 GB total new data). How long would it take to sync the array?
I used to use Flexraid, which took 4 days to build my 80TB array, snapraid does this in around 26hrs, add to that flexraid had serious memory leaks that were not fixed when i stopped using the product, and snapraid just works.
To me the speed of snapraid is the absolute best thing
Looking at my last log: I added 50GB, sync took 22 minutes. This is with 6 data discs, 2 parity, all 7200 rpm.
Time should be proportionate to the amount of new data, but the distribution of content on the data discs will matter. If one disc is being filled and the others are empty past a certain level, I presume the sync runs faster.
-Bill
The opposite, actually. If you add 10GB to one of 10 data drives, SnapRAID has to read and process 100GB (10GBx10 drives). If you added 10 GB across each 10 drives, 1 GB per drive, SnapRAID only has to read 10GB (1GBx10 drives). This is vast oversimplification and doesn't account for many other factors, but it should demonstrate why spreading out data typically results in faster syncs.
Last edit: Quaraxkad 2015-11-21
Bill, Benny - thank you for your helpful comments.
This is not a question that anybody can answer for you, which is why it's not clearly answered! There are too many variables, you'll just have to run it yourself to see how long it takes. It's affected by the speed of the drives, the number of drives, the ability of your hardware and controller cards to handle simultaenous reading and writing to multiple devices, the number of files on the drives, the amount of data on the drives, the speed of the processor and memory, etc. There's absolutely no way to estimate how long your sync will take.
True, however,i run snapraid on 3 different boxes,all with different hardware,ranging from IBM1015m IT mode SATA controllers with WD40EFRX to an old gigabyte uhd-55 motherboard using on board sata controllers with old 500GB-1TB WD and Seagate drives, and ranging in size array from 80TB on my home media storage server,to my 12TB home video,vacation photos and all manner of backups,and ALL run smooth and fast with snapraid.
I just tried flexraid again today,and i could not get read speed past 12mb/s and snapraid on same box runs at 70mb/s HUGE difference..
I am currently running a new parity on my home media server, with read speeds of 110MB/s, flexraid again never get past the 18MB/s read speed on this box.
Also, the ETA reported from snapraid is quite accurate, where as flexraid, you can never tell if program has crashed or stopped as there is no progress indicator,and this is extremely annoying.
Add to that the new low memory use, it is an absolute winner.
Only thing i would like is a gui with email reporting and initial setup,as commandline can be daunting to a lot of people.
Last edit: Benny King 2015-11-21