[Bug] SSD Cache - Copy fails when nearly full and [Bug] "Unusable for duplication"

[Spider99]

As i understand it when the SSd cache becomes full it should fall back to the Archive drives

 

But

 

If you are copying large volumes of data (internally within the server in this case) it will fail 50% of the time

 

Basically what appears to be happening is

 

If the ssd's are beyond their limit % full setting the next file will fall back to the archive drives - as expected - (in my case 95% full)

 

However if the ssd's are not at or near the % full setting and the next file exceeds the remaining space on the ssd's (large video files) then the copy fails with a STREAM(????) error - not good for unattended large copies 

 

If you get the pool to balance and create sufficient space the copy will proceed - however this "paused" copy has an unwanted side effect as it generates a large amount of "Unusable for duplication" data in my case over 700GB worth - checking the disks sizes and comparing file size totals - with checking for hidden files and running a full chkdsk /f on all drives did not show any errors or orphaned files - its appears to be a bug in the calc by DP - as copying more data to the pool reduces the "Unusable for duplication" by the amount copied . In my case there are no other files on these disks only the pool part dir, recycle bin and SVI - both SVI and recycle bin are turned off and empty as they were the first things i checked.

 

Have a suspicion that the amount of "Unusable for duplication" is the size of the copy which "fails" and if you have more than one it is cumulative - difficult to check as it depends what files are copied and their sizes to induce the error.

 

I did reboot to see if it would solve the issue - no joy

I remeasured the pool a couple of times - no joy

 

i just copied 203GB of data to the pool and the  "Unusable for duplication" dropped from 502GB to 299GB - as each file was copied the total dropped by that amount during the copy.

Doing a second copy of 296GB to see if i end up with ~ 3GB left in "Unusable for duplication" - total is dropping by file copied as seen in first copy. [edit] - ended up with 3.34GB unusable left after copy. Now it is back to normal as have copied more data across to the pool and do not have Unusable anymore.

 

DP version 740 Beta

Win 2012r2 SE

Pool in question is not duplicated

Pool is second pool on server - if that makes any difference

 

If you need any logs etc let me know

Edited February 19, 2017 by Spider99

[Spider99]

As an update i noticed today when adding a drive to the pool showing the error above that the Unusable flag came back

 

but only briefly (few seconds) with the 702GB total it started with

 

The pool is back without any Unusable flag now - thought it might help with finding the issue

[Christopher (Drashna)]

Could you grab logs of the specific "Stream" error you're seeing (as well as a screen grab/shot)?

http://wiki.covecube.com/StableBit_DrivePool_2.x_Log_Collection

 

And: http://dl.covecube.com/Troubleshooter/StableBit.Troubleshooter.exe

 

 

As for the "unusable for duplication", that depends on your pool, but this is very normal.  If needed, enable the "Duplication Space Optimizer" balancer, as this will attempt to rebalance the data on the pool to clear out the "Unusable for duplication" space. 

 

http://community.covecube.com/index.php?/topic/37-faq-unduplicated-vs-duplicated-vs-other-vs-unusable/

[Spider99]

Ok will try as have some more data to copy across to the pool and a another disk to add to the pool

[Spider99]

I added a new disk but the Unusable message did not reappear - so guess its been cleared

 

Will try copying some data to see if i can get some unusable back again

[Christopher (Drashna)]

Well, you don't really want the "unusable" space here.

[Spider99]

Well i created a new pool on a different machine (win 10 vs win 2012r2) and the UNusable is back

 

After a lot of checking and messing around as nothing would clear it - no other data on the pool drives - no SVI and no Recycle bin - remeasure does not change the values - copying extra data to pool does not change the values

 

Turning on duplication (other pool does not have this on) changes the value - tends to wander about - and finally settles on a new value

 

I removed each disk in turn and deleted the volume and then recreated it and re added it to the pool

 

The unusable returned until i had done each disk in turn - nothing special or different about the last disk

 

I am very suspicious this is a bug in 740 as prior to changing to this version not seen this error

 

Ha scratch that Unusable is back again!

 

There are only two directories on the drives - recycle bin and poolpart 

 

Any explanation for the wired numbers????

 

 

 

 

 

 

[Christopher (Drashna)]

This is most likely "fine". 

 

While, I know these are not "small" drives for SSDs, they are "small". 

 

Chances are that one drive is using more data than the other, specifically in slack space or directory entries, etc.   This would cause the "Unusable for duplication".   And because there are only two disks, a small discrepancy will actually cause this to occur. 

 

If you add more disks, it will likely disappear, after balancing. 

[Spider99]

Hi Chris

 

The Small pool - i figured out its because the drives are actually slightly different in size - bought a couple of months apart - and as only have two drives - that's why it pops up.

 

 

Going back to the first post - any answers to the other way i have found to generate unusable - and specifically the over fill problem with the SSd Cache which sets it off?

[Christopher (Drashna)]

lol, yeah. the drives being slightly different in size would absolutely cause this, as well.

 

It's a possibility that was in the back of my mind, but I didn't really mention. Not sure why. 

 

 

Going back to the first post - any answers to the other way i have found to generate unusable - and specifically the over fill problem with the SSd Cache which sets it off?

 

You mean the failing on writes when the SSD drives are full? 

No, it should fall back on the archive drives without a problem in this case. 

 

In fact... my pool is doing that "as I type", because  I'm importing a bunch of data right now.

 

Unless you're using file placement rules as well as the SSD Optimizer, I'm not sure why this would occur.  

 

But if you can get tracing logs of this happening, it may be helpful.

http://wiki.covecube.com/StableBit_DrivePool_2.x_Log_Collection

Eg, enable the logging, copy files over, stop logging.