bug#31345: what is wrong?

[rbre gmx]

Hello,
I have an dell vostro 3000 notebook with 480 GB SSD and 16 GB RAM.A
USB3 port that does not work under Debian Stretch (9).A 500 GB HDD on
USB2 port and the performance is ....
In the individual tests the values are acceptable.In practice, the
values collapse. WHY? what is my mistake?Please helpThanks in advance
With clonezilla-live-2.5.5-38-i686-pae startet from Sardu USB StickI
have Velues between 2000 / 2700 MB/s and not 9.6 MB/s

Debian Stretch (9) dd (coreutils) 8.26
Create drive image "compressed" (Knoppix 8.1)dd if=/dev/sda | bs=2048
ibs=262144 obs=2048 conv=notrunc,noerror gzip
-9>/media/sdc1/backupimage/20180424avostro.img.gz
480103981056 bytes (480 GB, 447 GiB) copied, 50246.9 s, 9.6 MB/s

Create drive image "compressed" (Deb9 X64)dd if=/dev/sda7 | mbuffer -s
512 -b 4096 -H | seek=4096 conv=notrunc,noerror gzip
-9>/media/user/RB4TB/backupimage/20180424avostroP7a1.img.gz
243716325376 bytes (244 GB, 227 GiB) copied, 27661.7 s, 8.8 MB/s in @
8567 KiB/s, out @ 12.0 MiB/s,  227 GiB total, buffer   8% full summary:
 227 GiByte in 7h 41min 01.9sec - average of 8604 KiB/s
Single Checksdd if=/dev/zero bs=1M count=1024 | md5sum1073741824 bytes
(1.1 GB, 1.0 GiB) copied, 3.91711 s, 274 MB/s
dd if=/dev/zero bs=4M count=4096 | md5sum17179869184 bytes (17 GB, 16
GiB) copied, 62.4363 s, 275 MB/s
dd if=/dev/zero bs=1M count=4096 | md5sum4294967296 bytes (4.3 GB, 4.0
GiB) copied, 15.4608 s, 278 MB/s
dd if=/dev/zero bs=1M count=2048 | md5sum2147483648 bytes (2.1 GB, 2.0
GiB) copied, 7.72068 s, 278 MB/s
dd if=/dev/zero bs=4M count=1024 | md5sum4294967296 bytes (4.3 GB, 4.0
GiB) copied, 15.6031 s, 275 MB/s
dd if=/dev/zero bs=1M count=2048 | md5sum2147483648 bytes (2.1 GB, 2.0
GiB) copied, 7.72068 s, 278 MB/s
dd if=/dev/zero bs=1M count=256 | md5sum268435456 bytes (268 MB, 256
MiB) copied, 0.97249 s, 276 MB/s
dd if=/dev/zero bs=1024 count=256 | md5sum262144 bytes (262 kB, 256
KiB) copied, 0.00151299 s, 173 MB/s
Scriptsobs_test.shibs_test.shhttp://www.alecjacobson.com/weblog/?p=635
id="-x-evo-selection-start-marker">
RegardsRalph

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