I have a truenas scale home lab which I use as a media centre for friends and family. It is running HDDs in a mirror and currently I am using truecharts apps for plex etc but want to move to a VM with proper docker support. As known in Wendel’s guide to truenas, he sets up his own vm and connects back to the nas via a NFS share.
So as you’ll know, writes are painfully slow doing this. So the solution is either to turn off sync writes or add a slog.
Problem is, our dish washer shorts out and basically turns off the entire house. This will eventually get fixed but my server does have the risk of losing data due to a power outage (for the time being).
I don’t want to buy both a UPS and a second hand enterprise ssd. I can’t seem to make up my mind on whether I should go with the slog or just get a UPS that triggers a shutdown when power loss has been seen. You guys will have a clearer mind on the topic than me.
Again this is to speed up NFS writes while also protecting the data.
This is probably an age old question but thanks for reading and helping me out.
Belatedly … in that scenario, UPS for sure. I can’t speak to whether or not disabling sync writes is a good idea, though.
Anecdotally, I’ve had good luck with APC, and a 50/50 on DOA with Eaton. But my sample size is 3, so I wouldn’t let that 50/50 dissuade you. The APC one I have I wouldn’t recommend for your scenario (it’s a dumb standby unit, rather than line interactive).
The Eaton one I have is a 5SC 500 – which may or may not be sized correctly for your server, and the larger VA units in that particular tower-style range all have active fans for cooling so are probably not ideal for home use (if it’s in a room where people will be). I will say their support line was absolutely stellar about replacing the dead one, though.
Yes indeed! We are waiting for other works to be done before moving on with the rest of the house. But fixing the machine won’t improve sync write speeds and disabling sync writes can be risky business without a ups to safely shutdown the server. Plus there’s no telling what other appliance/government restrictions will cause the electricity to go out.
But it would it does appear apparent that I will be a UPS, if only to disable sync writes to get max performance instead of messing around with a slot and second hand enterprise drives.
Maybe I have been misinformed. From what I understand, disabling sync writes on ZFS can lead to 5 seconds (roughly) of data in the ZFS cache to be lost in the event of a power outage leading to data corruption/loss. I’m sure it’s not a massive deal to stress over but its one of those things I’d rather not have to worry about, rather than live with it, i’d like to find a solution. I was curious how other people are dealing with Truenas scale, VMs and transferring files back and forth from the ZFS NAS to VMs without painfully slow write speeds.
Sorry for the late reply, but yes. I personally use a mirrored pair of Intel Optane 3DXPoint 64GB SSDs for this. They work great and were pretty cheap. And yes, 5 secs doesn’t sound like a lot of data to lose until this happens at just the wrong time and you corrupt something important, like your ZFS metadata or something similar on the VM you’re running.
But I’m actually team UPS and SLOG really. The UPS protects your system from bad power quality, I run them on all my important stuff.
If I had to pick one, I’d go UPS, but I’d also keep sync set to standard and live with the slow writes until I could buy a decent SLOG solution. To summarize, I find my life is better when I don’t try to outsmart the engineers that designed the thing. ZFS sync is setup this way for good reasons, and I agree with those reasons.