Performance Issues with Debian@Zyxel NSA 325v2 (no replies)

Hello everybody,

I've installed Debian on my Zyxel NSAv2 NAS in order to get rid of the awful legacy Zyxel UI.

The installation worked perfectly, debian is now running on my nas. I've installed it on a SD card, located in a SD Card reader in one of the read USB ports (none of my "normal" pen drives worked).

root@debian:~# uname -a
Linux debian 3.14.0-kirkwood-tld-1 #1 PREEMPT Tue Apr 1 22:54:58 PDT 2014 armv5tel GNU/Linux

Unfortunately , I've got some speed issues. When rsyncing a file from the first harddisk to /dev/null I get an average speed of 24.59MB/s. While running a backup with rsync from one disk to the other, i get transferspeeds around 15MB/s

Sometimes, the drives are realy slow:

root@debian:~# dd if=/media/Daten/Daten/Videos/Neu/movie.mkv of=/media/Backup/Daten/Videos/Neu/movie.mkv oflag=direct
220932+0 records in
220932+0 records out
113117184 bytes (113 MB) copied, 370.886 s, 305 kB/s

Running hdparm benchmark I get the following results, harddisk was unmounted during the tests:

root@debian:~# hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:   538 MB in  2.00 seconds = 268.61 MB/sec
 Timing buffered disk reads: 318 MB in  3.02 seconds = 105.27 MB/sec
root@debian:~# hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:   638 MB in  2.00 seconds = 319.04 MB/sec
 Timing buffered disk reads: 394 MB in  3.02 seconds = 130.68 MB/sec
root@debian:~# hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:   634 MB in  2.00 seconds = 316.26 MB/sec
 Timing buffered disk reads: 392 MB in  3.01 seconds = 130.02 MB/sec

This is my first harddrive:

root@debian:~# hdparm -I /dev/sda

/dev/sda:

ATA device, with non-removable media
	Model Number:       WDC WD30EURX-63T0FY0                    
	Serial Number:      WD-WCC4N0069999
	Firmware Revision:  80.00A80
	Transport:          Serial, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0

This is the second harddrive:

/dev/sdc:

ATA device, with non-removable media
	Model Number:       ST3000VX000-9YW166                      
	Serial Number:      Z1F1G645
	Firmware Revision:  CV13    
	Transport:          Serial, SATA Rev 3.0

I've formated both drives with btrfs.

SMART tells me, the drives are fine:

root@debian:~# smartctl -H /dev/sda
smartctl 6.4 2014-10-07 r4002 [armv5tel-linux-3.14.0-kirkwood-tld-1] (local build)
Copyright (C) 2002-14, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

root@debian:~# smartctl -H /dev/sdc
smartctl 6.4 2014-10-07 r4002 [armv5tel-linux-3.14.0-kirkwood-tld-1] (local build)
Copyright (C) 2002-14, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

Does anybody have an idea, why the performance isn't as expected? When moving files on the harddrives attached to an Windows PC and installed in an external USB case I get transferspeeds around 100MB/s.