Random (?) slow write speed to OMV under Xubuntu, Win7 is ok

I understand it's likely NOT an OMV issue, but I will try seeking help here nevertheless.

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I am experiencing some very slow write speeds (about 12-15 MB/s, sometimes even less than that - over a gigabit network) under Xubuntu 16.04 lately.

At first I thought it was due to the recent 3.x OMV upgrade but since it runs off a USB pendrive I immediately reverted to the old 2.x distribution and the issue is still there.

Some details about the tests I made:

- client PC is a Core i3 6100, 16GB RAM, main drive is a Samsung SSD, test data being copied to the NAS is on a separate WD Green 500GB hard disk
- network is gigabit (ethtool confirms gigabit full duplex)
- client PC has dualboot with Windows7 64bit, and NAS is working flawlessly there (100+ MB/s), as it did under Xubuntu until recently
- iperf benchmarks on both Xubuntu *and* the NAS shows about 950 Mb/s
- the network share is accessed via cifs/smb
- sometimes write speed (data used for the test is usually huge files ranging from 500 MB to 2-3 GB) goes back to normal, then horribly crawls at 1 MB/s or even less

Considering the huge performance differences between Xubuntu/Linux and Windows7 on the very same hardware I have to guess the issue isn't on the server side (i.e. the NAS) but on the client instead.

But I really have no idea what to look for, so any suggestion is surely appreciated.

First of all, thanks for the quick reply!

Shares are currently mounted via static entry in fstab (left basically untouched since forever, I had a "proper" NAS before switching to OMV so I just used the same IP and share names/path), but I am not a huge Linux expert unfortunately... I *guess* the answer is "no, I don't use any virtual filesystem" but could you please confirm this is the case?

I'll double check just to be absolutely sure, and post mtab contents as well later.

sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
udev /dev devtmpfs rw,nosuid,relatime,size=8130136k,nr_inodes=2032534,mode=755 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
tmpfs /run tmpfs rw,nosuid,noexec,relatime,size=1630124k,mode=755 0 0
/dev/sda2 / ext4 rw,noatime,errors=remount-ro,data=ordered 0 0
securityfs /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 0 0
tmpfs /dev/shm tmpfs rw,nosuid,nodev 0 0
tmpfs /run/lock tmpfs rw,nosuid,nodev,noexec,relatime,size=5120k 0 0
tmpfs /sys/fs/cgroup tmpfs ro,nosuid,nodev,noexec,mode=755 0 0
cgroup /sys/fs/cgroup/systemd cgroup rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd 0 0
pstore /sys/fs/pstore pstore rw,nosuid,nodev,noexec,relatime 0 0
cgroup /sys/fs/cgroup/cpu,cpuacct cgroup rw,nosuid,nodev,noexec,relatime,cpu,cpuacct 0 0
cgroup /sys/fs/cgroup/devices cgroup rw,nosuid,nodev,noexec,relatime,devices 0 0
cgroup /sys/fs/cgroup/net_cls,net_prio cgroup rw,nosuid,nodev,noexec,relatime,net_cls,net_prio 0 0
cgroup /sys/fs/cgroup/pids cgroup rw,nosuid,nodev,noexec,relatime,pids 0 0
cgroup /sys/fs/cgroup/freezer cgroup rw,nosuid,nodev,noexec,relatime,freezer 0 0
cgroup /sys/fs/cgroup/blkio cgroup rw,nosuid,nodev,noexec,relatime,blkio 0 0
cgroup /sys/fs/cgroup/perf_event cgroup rw,nosuid,nodev,noexec,relatime,perf_event 0 0
cgroup /sys/fs/cgroup/hugetlb cgroup rw,nosuid,nodev,noexec,relatime,hugetlb 0 0
cgroup /sys/fs/cgroup/cpuset cgroup rw,nosuid,nodev,noexec,relatime,cpuset 0 0
cgroup /sys/fs/cgroup/memory cgroup rw,nosuid,nodev,noexec,relatime,memory 0 0
systemd-1 /proc/sys/fs/binfmt_misc autofs rw,relatime,fd=24,pgrp=1,timeout=0,minproto=5,maxproto=5,direct 0 0
hugetlbfs /dev/hugepages hugetlbfs rw,relatime 0 0
mqueue /dev/mqueue mqueue rw,relatime 0 0
debugfs /sys/kernel/debug debugfs rw,relatime 0 0
fusectl /sys/fs/fuse/connections fusectl rw,relatime 0 0
tmpfs /tmp tmpfs rw,noatime 0 0
binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,relatime 0 0
//192.168.0.10/MugghieraBackup /mnt/NAS/mugghiera cifs rw,relatime,vers=1.0,cache=strict,username=bennyuser,domain=OPENMEDIAVAULT,uid=0,noforceuid,gid=0,noforcegid,addr=192.168.0.10,unix,posixpaths,serverino,mapposix,acl,rsize=1048576,wsize=65536,echo_interval=60,actimeo=1 0 0
//192.168.0.10/BennyBackup /mnt/NAS/bennyuser cifs rw,relatime,vers=1.0,cache=strict,username=bennyuser,domain=OPENMEDIAVAULT,uid=0,noforceuid,gid=0,noforcegid,addr=192.168.0.10,unix,posixpaths,serverino,mapposix,acl,rsize=1048576,wsize=65536,echo_interval=60,actimeo=1 0 0
tmpfs /run/user/108 tmpfs rw,nosuid,nodev,relatime,size=1630124k,mode=700,uid=108,gid=114 0 0
tmpfs /run/user/1000 tmpfs rw,nosuid,nodev,relatime,size=1630124k,mode=700,uid=1000,gid=1000 0 0
gvfsd-fuse /run/user/1000/gvfs fuse.gvfsd-fuse rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0

I'm back, here's the full output of cat /etc/mtab as requested.

Needless to say, NAS shares are shown at line 30 and 31

Anything strange?

I did some extra testing during the weekend: tried booting from a live Xubuntu 16 USB (64 bit) and manually mounting the NAS share, and also installing an empty 2.5" HD with a dedicated share, just to be sure there were no issues with the previously installed drives. I also replaced the whole gigabit chain by inserting a gigabit switch before the modem/router with a different pair of ethernet cables. Still getting the same results so I reverted back to to original configuration.

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It seems to me there is a correlation (again, I may be missing something obvious) between stuff that is actually being copied and the resulting speed.

When I try to trasfer mixed sized files (a mixture of 3-4 MB jpeg and several hundreds MB sized mp4 and/or tar.gz archives, for a grand total of about 2-3 GBs) average write speed is considerably higher, while transfering a single mp4 of the same size (i.e. 2-3 GBs) goes back to 15-20 MB/s.

Is this expected behaviour?
If so, I honestly hadn't noticed before. :-\

PS: I also get some serious issues (basically, video constantly hangs and reproduction turns out being impossible) while trying to play the aforementioned 2-3 GB mp4 HD videos from the NAS (via VLC), if that rings a bell...