Reporting: Process Lasso may have fixed "Delayed Write Failed"

Arbor · July 30, 2013, 05:16:36 PM

On both my previous Win XP and now Windows 7 (32-bit) I have occasionally had "Delayed Write Failed" issues when copying large files between external (USB3) drives. I use the excellent, free "FastCopy" utility for these operations, and don't believe it is contributing to the problem.

DWF is a very bad error since it can involve data loss, and takes a lot of recovery time. There are many web reports of it and people trying to find something that will help. I recently had it happen twice in an hour with one particular drive. Looking around, I noticed the I/O Priority setting in PL. I set this to "High" for FastCopy, instead of the original "Very Low". Following that, with a couple of terabytes copied, I have had no timeout errors on that drive.

So... I'm thinking that Process Lasso may be the solution for Delayed Write Failed, at least for my usage. This is great if so. I'll try to remember to post back if I get another DWF.

Thanks again for a great product.

Arbie

BenYeeHua · July 30, 2013, 05:54:04 PM

Interesting...
Maybe the bus is busy and there are some issues on the I/O priority.

Jeremy Collake · July 31, 2013, 04:08:21 PM

The Very Low I/O priority is specifically for background I/O. So, changing the I/O priority would certainly change the behavior of the I/O, possibly getting it out to the storage device before it times out, or becomes otherwise unavailable.

You should make sure that in the Policies of those devices (see hardware properties), 'Turn off Windows write-cache buffer flushing on the device' is unchecked (the default). If you have tweaked this setting, and prefer to keep the performance advantage of not flushing the write-cache, then you should *always* use the 'Safely remove' feature when unplugging those drives. If you have this problem, I'd definitely make sure that write-cache buffer flushing for these devices is enabled. The performance difference will be negligible in most all scenarios.

... Oh, and the 'Fastcopy' utility may very well force write caching, which would be a primary cause of the problem if the buffer flushing policy has not been changed.

Either way, use Safely Remove, or quit with the enhanced write caching ... However, if a change in I/O priority adjusts the timing enough to mitigate the problem, then you're good!

BenYeeHua · July 31, 2013, 05:25:55 PM

Ya, forgot about the "very low" is only for the background I/O.

Arbor · July 31, 2013, 08:15:54 PM

Yes, I long ago made sure these devices are configured for safe removal with write-cache flushing enabled. That's one of the first things people look for on Delayed Write Failures. There are many posts on DWF, and some people even have problems with this on internal drives. I'm glad I don't. However, as far as I can recall, I never saw discussions of I/O priority.

In general, people copying lots of big files will not be using the Windows "Copy" command. To batch things, sequence, monitor, and pause them, and verify the copies, all require a third-party tool. PL can set that tool to "High" I/O priority. A plus for the program, I'd say.

Arbie

Jeremy Collake · August 01, 2013, 12:54:27 PM

I'm happy to hear that Process Lasso was able to make the difference

. It's an interesting report, other people may find this tip useful.

Thanks for posting your experience!

Arbor · November 20, 2015, 10:21:16 AM

Reporting again... 2.5 more years with no delayed write failures. Faster hardware is probably helping, but I think Process Lasso's ability to prioritize I/O is key. Posting here in hopes that Google searches for Windows "delayed write failed" solutions will find it.

edkiefer · November 20, 2015, 10:51:27 AM

Maybe you should post or contact FastCopy Dev's so maybe they need to address this (low priority) issue, if your doing this not in the background I don't think its right, but i am no expert on I/O.
Also don't know if it will help but maybe check drivers for storage controller, Intel or whoever it is.

Jeremy Collake · November 20, 2015, 12:31:32 PM

Quote from: Arbie on November 20, 2015, 10:21:16 AM
Reporting again... 2.5 more years with no delayed write failures. Faster hardware is probably helping, but I think Process Lasso's ability to prioritize I/O is key. Posting here in hopes that Google searches for Windows "delayed write failed" solutions will find it.

Great to hear

.

I'm in agreement with Ed here. What you are seeing in Process Lasso (or rather yourself via Process Laaso!) fix a bug in FastCopy. It probably starts itself via the Task Scheduler and is unaware that when applications do that, they inherit the Task Scheduler's low I/O priority class.

BenYeeHua · November 21, 2015, 05:52:18 AM

Quote from: Jeremy Collake on November 20, 2015, 12:31:32 PM
Great to hear .

I'm in agreement with Ed here. What you are seeing in Process Lasso (or rather yourself via Process Laaso!) fix a bug in FastCopy. It probably starts itself via the Task Scheduler and is unaware that when applications do that, they inherit the Task Scheduler's low I/O priority class.

Well, it is expected behave, it is design to do so.

Here is quote from the help doc.

QuoteSpecify "Full Speed", "Auto Slow"(*1), "90%"~"10%", "Suspend".
If you feel it is hogging resources, it is recommended to set to "Auto Slow" (If it detects mouse moving/active window changing (and FastCopy window is not foreground), it is slowed down).
If "Full Speed" is not selected, low process priority class is set.
(This setting is not saved by job manage)

So if you are using default config which is "Auto Slow", then it will change the I/O priority.