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So I have an Ubuntu server I've built myself. However, today it has started crashing pretty regularly but I can't figure out why.

At first I thought it might correspond to Time Machine backups so I disabled Time Machine completely. Crash still happened. I can say that in each instance I was accessing the server, namely streaming content. I was also downloading torrent files at the time.

At some point the server would become unresponsive and whatever I was streaming would seize. I would try logging into Webmin but the page would time out. As would any other page being pulled from the server. I would also trying creating an SSH connection but it would say no host connection available.

Eventually I'd do a hard restart of the server and it would be back to behaving as if nothing had happened.

However, it has happened multiple times now and I do not know why. I'm afraid, when it comes to Ubuntu, I'm something of a newb. I don't know where to find the error logs and I've been doing some searching. I'd appreciate any director someone can point me in.

OS: Ubuntu Server 12.04
Processor: 3.30 Ghz Intel Core i3
Boot Volume: 40 GB SSD
Storage: 5 x 2 TB HDD in ZFS zraid1 array

Since restarting I've checked and all my packages are up to date. I don't believe I'm maxing out my RAM and I'm only using about 40% of my mount volume, less of my storage volumes.

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Could it be a faulty NIC driver? You say it always happens when you're streaming content. – user3463 Jul 30 '12 at 6:07
I don't think so if only because I use it as a download server, dropbox server, etc. It's connected to the net and doing things pretty much all day but it only seems to crash when I'm streaming HD video content. Over ethernet, I should say. – dougoftheabaci Aug 1 '12 at 17:15
I've been putting my server under some more strain for the last few days and I can't get it to crash again. I have a theory that it might be related to a sort of perfect storm of things. When the crashes were happening, I was downloading a lot of HD video via torrent and streaming large, HD videos to another computer. Bonus points for that computer having a brand new OS. Is there no system log for crashes? – dougoftheabaci Aug 1 '12 at 17:17
up vote 0 down vote accepted

I would point out that ZFS is not mature in Linux and that the file system is a system hog when doing a lot of writes and reads. Even the developers warn you of that on their page.

Had a similar issue using it on 11.10 where the all system would slow down up to a point where opening a Firefox tab while copying a couple of gigabytes of files to the ZFS mounts would be impossible, even while not maxing out the RAM and with plenty of space left on the ZFS mount.

I would start by getting an external USB disk with EXT4 (or just degrade / remove one of the disks from the ZFS RAID if you are comfortable with it), remove the ZFS mount and test your system operations while using the external USB as storage.

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I could simply not mount the ZFS volume to do this. The SSD is an EXT4 partitioned volume all to itself. – dougoftheabaci Jul 31 '12 at 1:30
sure, as long as it's not in use – Bruno Pereira Jul 31 '12 at 7:02

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