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 Post subject: Re: New DeepSpar USB Stabilizer
PostPosted: April 2nd, 2019, 8:24 
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maximus wrote:
Can the USB Stabilizer do this with some setting? That could be a big winner if it worked. I just did a basic test using the two USB only drives that I have (which are both WD), and it would seem that it would work on both.

The block size was determined by the imaging program used. I don't believe there's a setting in the Stabilizer program to change that. It is displayed on the sector map screen and is constant throughout the imaging task, 128 sectors for all but the DMDE task. I can change it for successive DFL passes when I do multi-pass imaging with the DFL, going from 2048 to 128 on passes 1 and 3. The Stabilizer could be using a different (varying) block size and reporting what size the imaging program is using, I suppose.

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 Post subject: Re: New DeepSpar USB Stabilizer
PostPosted: April 2nd, 2019, 17:15 
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Joined: January 29th, 2012, 1:43
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Location: United States
Just a quick response to this for now. Even if the program (in this reference DFL) requests to read 2048 sectors, when going through the Windows API, it is only really requesting to read 1,048,576 bytes (2048 * 512). I can tell you that in Linux, there is a normal limit of 256 sectors, meaning if you request more than that, it will split the reads up, so a request of 2048 sectors would be split into 4 read commands (or more if the read request does not fall on a 512 byte boundary). Actual numbers for Windows could be seen by sniffing the USB communication. So the only way to increase the actual read size would be a form of read-ahead performed by the USB Stabilizer.

I am still not sure where I am at with attempting any sort of implementation, but the idea of possibly being able to improve slow responding cases in a drastic way has peaked my interest a bit more.

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 Post subject: Re: New DeepSpar USB Stabilizer
PostPosted: April 2nd, 2019, 20:48 
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Joined: January 29th, 2012, 1:43
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To add to how the USB Stabilizer could incorporate a read-ahead feature to assist with slow responding drives, it would first need to have a somewhat decent RAM buffer, 32MB would be the max it should need. Then you have an option to enable a progressive read-ahead. The first read would only read what was asked for, and any sequential reads following would induce a read-ahead multiplier up to an adjustable limit. If a read was not sequential, then the read-ahead multiplier is reset. The Linux OS itself actually does this, and I would think Windows does also. The USB Stabilizer could take it to the next level. It would work best with cloning, since reads would be sequential. It can also work with file level access, but allowing too high of a limit can cause the opposite effect of a slowdown.

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 Post subject: Re: New DeepSpar USB Stabilizer
PostPosted: April 2nd, 2019, 22:28 
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Joined: January 29th, 2012, 1:43
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With the one WD drive I do have that has a slow issue, and using the Sabrent USB adapter, with the max cluster size of 240 for the passthrough, a five minute test calculated that it would take a little over 31 days to clone. I did a five minute test on the same drive with direct USB and the max 65535 cluster size, which actually hit some sort of issue before the 5 minute mark (maybe bad sectors), and it still made it far enough to be 99.5 times faster, putting it at under 8 hours to clone. I cannot be sure if all drives would work like that, but that is one hell of a result.

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 Post subject: Re: New DeepSpar USB Stabilizer
PostPosted: April 3rd, 2019, 0:01 
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Joined: September 8th, 2009, 18:21
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maximus wrote:
I did a five minute test on the same drive with direct USB and the max 65535 cluster size, which actually hit some sort of issue before the 5 minute mark (maybe bad sectors), and it still made it far enough to be 99.5 times faster, putting it at under 8 hours to clone. I cannot be sure if all drives would work like that, but that is one hell of a result.

Agree. Very nice!

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 Post subject: Re: New DeepSpar USB Stabilizer
PostPosted: July 6th, 2019, 23:31 
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Joined: January 29th, 2012, 1:43
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Location: United States
pcimage wrote:
Not really, I’ve just ordered one. Will report on its performance in a while.

I’ve got some nasty PCI-E SSD’s to test it on. They all have been recovered but were a right royal PITA. If this increases the quality and speed of recovery then it’s worth it to me :-)

So have you had good results with the USB Stabilizer on these?

I have been (very) slowly working on my direct USB code for HDDSuperClone, and finally have some working alpha code. When I finally get to the beta level, I may be interested in having someone test it. And I may not mind a bit of head-to-head competition with the stabilizer :D

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 Post subject: Re: New DeepSpar USB Stabilizer
PostPosted: July 15th, 2019, 7:47 
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Joined: July 15th, 2019, 7:24
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Thank you for the information very useful.


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