Sorry for the duplicate post. I had an email client error that
accidentally caused me to hit send on the window I was composing in.
On 8/20/22 1:15 PM, Dale wrote:
Howdy,
Hi,
Related question. Does encryption slow the read/write speeds of a
drive down a fair amount?
My experience has been the opposite. I know that it's unintuitive that
encryption would make things faster. But my understanding is that it
alters how data is read from / written to the disk such that it's done
in more optimized batches and / or optimized caching.
This was so surprising that I decrypted a drive / re-encrypted a drive
multiple times to compare things to come to the conclusion that
encryption was noticeably better.
Plus, encryption has the advantage of destroying the key rendering the
drive safe to use independent of the data that was on it.
N.B. The actual encryption key is encrypted with the passphrase. The
passphrase isn't the encryption key itself.
This new 10TB drive is maxing out at about 49.51MB/s or so.
I wonder if you are possibly running into performance issues related to
shingled drives. Their raw capacity comes at a performance penalty.
I actually copied that from the progress of rsync and a nice sized
file. It's been running over 24 hours now so I'd think buffer and
cache would be well done with. LOL
Ya, you have /probably/ exceeded the write back cache in the system's
memory.
It did pass both a short and long self test. I used cryptsetup -s 512
to encrypt with, nice password too. My rig has a FX-8350 8 core running
at 4GHz CPU and 32GBs of memory. The CPU is fairly busy. A little more
than normal anyway. Keep in mind, I have two encrypted drives connected
right now.
The last time I looked at cryptsetup / LUKS, I found that there was a
[kernel] process per encrypted block device.
A hack that I did while testing things was to slice up a drive into
multiple partitions, encrypt each one, and then re-aggregate the LUKS
devices as PVs in LVM. This surprisingly was a worthwhile performance
boost.
Just curious if that speed is normal or not.
I suspect that your drive is FAR more the bottleneck than the encryption
itself is. There is a chance that the encryption's access pattern is
exascerbating a drive performance issue.
Thoughts?
Conceptually working in 512 B blocks on a drive that is natively 4 kB
sectors. Thus causing the drive to do lots of extra work to account for
the other seven 512 B blocks in a 4 kB sector.
P. S. The pulled drive I bought had like 60 hours on it. Dang near new.
:-)
--
Grant. . . .
unix || die
