On 8/20/22 10:22 PM, William Kenworthy wrote:
What are you measuring the speed with - hdparm or rsync or ?
hdparm is best for profiling just the harddisk (tallks to the interface
and can bypass the cache depending on settings, rsync/cp/?? usually have
the whole OS storage chain including encryption affecting throughput.
How you measure performance is a complicated thing. There is the raw
device speed verses the speed of the system under normal load while
interacting with the drive.
At $WORK, we are more concerned about throughput of the drive in our day
to day use case than drive's raw capacity.
Encryption itself can be highly variable depending on what you use and
usually though not always includes compression before encryption.
Compression can be a very tricky thing. There's the time to decompress
and compress the data as it's read and written (respectively). Then
there's the throughput of data to the drive and through the drive to the
media. If you're dealing with text that can get a high compression
ratio with little CPU overhead, then there's a good chance that you will
get more data into / out of the drive faster if it's compressed than at
the same bit speed decompressed.
To whit I enabled compression on my ZFS pools a long time ago and never
looked back.
There are tools you can use to isolate where the slowdown occurs.
atop is another one that may help.
Yep.
[test using a USB3 shingled drive on a 32 it arm system]
Is that an Odroid XU4 system? If so, why 32-bit vs 64-bit? -- Or am I
mistaken in thinking the Odroid XU4 is 64-bit?
xu4 ~ # hdparm -Tt /dev/sda
/dev/sda:
Timing cached reads: 1596 MB in 2.00 seconds = 798.93 MB/sec
Timing buffered disk reads: 526 MB in 3.01 seconds = 174.99 MB/sec
xu4 ~ #
If that is an Odroid XU4, then I strongly suspect that /dev/sda is
passing through a USB interface. So ... I'd take those numbers with a
grain of salt. -- If the system is working for you, then by all means
more power to you.
I found that my Odroid XU4 was /almost/ fast enough to be my daily
driver. But the fan would kick in for some things and I didn't care for
the noise of the stock fan. I've not yet compared contemporary
Raspberry Pi 4 or other comparable systems.
--
Grant. . . .
unix || die
