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Old April 27th 20, 07:06 AM posted to alt.comp.os.windows-10,comp.sys.ibm.pc.hardware.storage
Yousuf Khan[_2_]
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Posts: 1,296
Default Why is this folder so slow?

On 4/26/2020 9:46 PM, Paul wrote:
Have you tried to "defragment" the drive ?


No, considering it's an SSD. But as you pointed out later, the optimize
option is available for both of my SSD's, but optimize recognizes them
as SSD's, so the only optimization available is trimming, no defragging.

Normally, the "optimize" dialog will not offer defragmentation
as an option in Windows 10. It's supposed to offer "TRIM" as
the option for an SSD.

However, there is a "Copy On Write" or COW issue with SSDs.
Under the right circumstances, there will be a slowdown.


Yes, likely this is exactly that circumstance. Do you know what the
symptoms of that circumstance are?

Now, consider what you're doing. Your backup software uses VSS
to make a shadow copy. It's possible some "COW activity" is happening
during the backup.


Yes, VSS is used by the software, which is Macrium Reflect 6 BTW.
Reflect's logs show that it creates the VSS shadows immediately before
beginning the backup.

This backup runs after midnight, and there is little activity while any
of the backups run. All of the backups run after midnight and they
finish relatively quickly, except this one.

The Optimize dialog knows about this, and the Optimize dialog
has some sort of metric it uses to decide what to do. While
most of the time, it will only offer TRIM, I bet in your
case, it's "going to have a COW" and defragment your drive.
This should not be as thorough as a regular defragment,
and the design of what's done, should have something to do
with whatever the root cause of "having a COW" is.


VSS is used on all of the backup jobs. None of the others exhibit this
behaviour. In fact, I've experienced this issue for nearly a decade now.
The problem started on Windows XP, continued on into Windows 7, and
continues to plague me in Windows 10. This particular folder has also
been migrated around from HDD to SSD, to a 2nd SSD, etc. So it's not a
problem that is specific to HDD's or SSD's, or to any particular version
of Windows.

I'll tell you what this folder is. It's actually my Thunderbird News
folder (exactly what I'm using to ask this question here), which exists
under the my User folder structure. The problem was discovered when I
started doing daily backups of my User folder and discovered that the
User folder was taking forever. After investigating it some, I figured
out that the problem was this particular substructure under News. Once I
excluded the News folder, backups finished 6 times faster! So I moved
the backups of the News folder to their own job, and let the rest of the
User folder get backed up separately. Before, you ask, I only backup the
News folder once a week, but it's still a pain in the ass watching it
take so long even once a week.

Some other background. When this particular backup is happening, it's
not the drives that are showing as busy, it's the CPU cores! 4 out of
the 8 cores on my FX-8300 are fluctuating between 50% to 100% busy,
while the other 4 are not that busy.

Yousuf Khan