I've noticed that write speeds to my external storage (3TB Seagate NAS Drives, connected to Odroid XU4 via USB 3), are far slower than they ought to be (~10 MB/sec). In reading some other threads, I saw a few suggestions that the linux kernel may be the issue. While I am on the latest version of OMV 3 (3.0.85), my kernel version is quite old at 3.10.104. In further reading, it appears that if I have OMV-Extras installed (which I do), I should see an option in the plugin for installing other backport kernel versions, but I don't see anything of the sort there. Is this because of the fact I'm using an ODROID XU4 and there just aren't any backports available that would be compatible, or is there something else wrong? Can someone point me to a "safe" way to install a more recent kernel version myself? I don't want to nerf my server, but I"d like to improve those write speeds.
Any/all help appreciated, as always.
UPDATE: One thing I notice is that when I pull up the OMV-Extras plugin, I *very briefly* see the "Kernel" tab show up, and then disappear as if some bit of logic may be hiding it (or some goofy bug I guess).
UPDATE 2: Doing a little further research on how to install new kernels, I've discovered that they require free space on the boot partition, and I currently have none. Perhaps that is why I do not see the option? My boot partition was only configured to be 70 MB by whatever image I used (I can't recall, but I started from a plain Debian image and laid OMV 3 on top of that). There are no additional kernel versions installed that I can remove to free up space, so I guess my only option is to resize my partitions. Assuming I can do that, would simply using "apt-get-install linux-image-flavour" work alright? I don't think I would try to move to the latest kernel available (which appears to be 4.9), but at least to 3.16 to see if that helps at all. apt-cache search linux-image reports that I can go to 3.16.0-4-armp, 3.10.105+, and various flavours of 4.9.
UPDATE 3: Apparently I didn't have write-caching enabled, which makes a HUGE difference in performance. Turned that on for each of my 3 disks, and I went from 10-12 MB/sec to 90-110 MB/sec. I assume there's no reason to NOT use that feature if I have it available to me? Some quick reading suggests it's mainly a concern on SSDs, and in scenarios where the transmission of data could be compromised, potentially corrupting or losing data. Former obviously not a concern, and I would hope the latter isn't either (I do have my server on a small UPS in the event of a power outage, which can probably keep it up and running for a good 20-30 minutes). The "Write Barriers" feature of EXT4 also seems to mitigate this somehow (though the understanding of such is beyond my grasp).