6.9 KiB
The Story
I was trying to migrate my data from one WD MyCloud EX 2 Ultra to another. This is my story of frustration, unanswered questions and a journey through bash + ssh.
TL;DR
Results
As of now, transfer speeds are consistently around 20-25 MB/s with the bottleneck being target drive write speed. Looking for possible causes.
Takeaways
- To check for network performance, start with
iperffor throughput, thenethtoolfor hardware layer and then proceed with tuning if necessary - To check drive performance:
hdparmandddfor read and write speeds, before checking transfer tools - In this case, there is no performance difference between
scpandrsync, athough if I wanted to resume broken copy process, rsync provides option to skip existing files (as a workaround in scp we can force this by removing write persmissions to already existing files)
Initial conditions
| Parameter | Source | Target |
|---|---|---|
| Device | WD MyCloud EX2 Ultra | WD MyCloud EX2 Ultra |
| Firmware | 2.31.204 | 2.31.204 |
| Drives | 2 x 3 TB WDC WD30EFRX-68N32N0, FwRev=82.00A82 | 2 x 4 TB WDC WD40EFRX-68N32N0, FwRev=82.00A82 |
| Raid | Raid-1 | Raid-0 |
| Encrypted | No | Yes |
| IP address | 192.168.1.54 | 192.168.1.53 |
Connected using Cat 5E cables via TP-Link TL-SG108 Gigabit switch.
Testing
First, I enabled ssh access in both NASes via web-ui:
Settings > Network > SSH
Default user for WD Mycloud EX2 Ultra is sshd so to connect to NAS I used command:
ssh sshd@192.168.1.53
To avoid multiple data transfers I logged into target ssh and tried to copy from source using scp command:
scp -rp sshd@192.168.1.54:/mnt/HD/HD_a2/Marcin /mnt/HD/HD_a2/
However, the transfer speed oscillated between 20-25 MB/s. This is way below expected 70 MB/s.
First I checked if network cards indeed connected using 1000 Mbps full-duplex using ethtool:
# ethtool egiga0
Settings for egiga0:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Advertised pause frame use: No
Advertised auto-negotiation: No
Link partner advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Link partner advertised pause frame use: No
Link partner advertised auto-negotiation: Yes
Speed: 1000Mb/s
Duplex: Full
Port: MII
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Link detected: yes
And that the IO and CPU are not saturated (those were already visible with web-ui, but I used iostat):
# iostat
Linux 3.10.39 (KlinkierChmurka) 05/05/20 _armv7l_ (2 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
29.23 6.16 28.23 1.36 0.00 35.02
# iostat -dx /dev/sda 5
Linux 3.10.39 (KlinkierChmurka) 05/05/20 _armv7l_ (2 CPU)
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.55 5.39 4.01 95.83 212.68 10755.40 219.70 0.45 4.53 4.82 4.52 1.19 11.90
I then checked if they are properly routing through the switch with traceroute:
# traceroute 192.168.1.54
traceroute to 192.168.1.54 (192.168.1.54), 30 hops max, 38 byte packets
1 192.168.1.54 (192.168.1.54) 0.428 ms 0.428 ms 0.391 ms
Then I enabled jumbo frames in the web-ui and verified they are working using ping:
# ping -s 8972 192.168.1.54
PING 192.168.1.54 (192.168.1.54): 8972 data bytes
8980 bytes from 192.168.1.54: seq=0 ttl=64 time=0.898 ms
8980 bytes from 192.168.1.54: seq=1 ttl=64 time=2.904 ms
8980 bytes from 192.168.1.54: seq=2 ttl=64 time=0.786 ms
To do performance test I stopped the scp pressing Ctrl-Z (that would allow me to resume it later using bg of fg) and ran a network throughput test using iperf:
Source:
# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.1.53 port 5001 connected with 192.168.1.54 port 41261
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 1.16 GBytes 991 Mbits/sec
Target:
# iperf -c 192.168.1.53
------------------------------------------------------------
Client connecting to 192.168.1.53, TCP port 5001
TCP window size: 93.3 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.1.54 port 41261 connected with 192.168.1.53 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 1.16 GBytes 992 Mbits/sec
This would rule out the network bottleneck. I decided to perform test on one large file using both scp and rsync, which can sometimes outperform scp.
# cd /mnt/HD/HD_a2/Marcin/
# dd if=/dev/zero of=1GB_TEST_FILE bs=1G count=1
1+0 records in
1+0 records out
1073741824 bytes (1.0GB) copied, 37.631790 seconds, 27.2MB/s
Starting with scp. Speed is consistent with what I obserwe with real data:
# scp -rp sshd@192.168.1.54:/mnt/HD/HD_a2/Marcin/1GB_TEST_FILE /mnt/HD/HD_a2/Marcin/1GB_TEST_FILE
sshd@192.168.1.54's password:
1GB_TEST_FILE 100% 1024MB 22.2MB/s 00:46
Now rsync. Unfortunately, no improvement there:
# rsync -a sshd@192.168.1.54:/mnt/HD/HD_a2/Marcin/1GB_TEST_FILE /mnt/HD/HD_a2/Marcin/1GB_TEST_FILE --progress
sshd@192.168.1.54's password:
receiving incremental file list
1GB_TEST_FILE
1073741824 100% 21.57MB/s 0:00:47 (xfer#1, to-check=0/1)
sent 30 bytes received 1073872980 bytes 20851903.11 bytes/sec
total size is 1073741824 speedup is 1.00
But wait, didn't the dd created the file on source NAS with speed around 27 MB/s? Time to bench the drives.
Source read speed:
# hdparm -t /dev/sda
/dev/sda:
Timing buffered disk reads: 538 MB in 3.01 seconds = 178.73 MB/sec
Target write speed:
# dd if=/dev/zero of=1GB_TEST_FILE bs=1G count=1
1+0 records in
1+0 records out
1073741824 bytes (1.0GB) copied, 41.367580 seconds, 24.8MB/s
Ok, so it would seem drive writing speed would be at fault. But why? SMB transfers to the drive are faster, 50-70 MB/s, close to advertised. And it would seem that I am not the only one with such problem (SCP slow, SMB fast):
- https://forums.freebsd.org/threads/slow-nfs-smb-afp-but-fast-scp-read-performance.68077/#post-410296
However, the benchmarks around web seem to find scp an rsync much faster than SMB:
Having depleted my theories I decided to ask WD community:
https://community.wd.com/t/wd-mycloud-ex2-ultra-2x4tb-slow-write-speeds-over-ssh/250988