Hey all! Quick question. Math is not my strong suit, I had a terrible time of it in high school. I wanted to ask, I have 5 8TB HDD drives in my TrueNAS server. the motherboard has 16GB and I was thinking of adding more Ram. Would 32GB be more suitable for that much storage? I read somewhere here about "Ram per Terebyte" but I didn't know if that was true or if I should upgrade to more system ram. Again, math isn't my strong suit so if someone knows how to convert/do the math of what I should add, I'd appreciate it.
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Ram to HDD TB size question
- Thread starter Grid21
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danb35
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The general guideline that's given is 1 GB of RAM per TB of drive capacity. It's left deliberately vague whether that's "raw" drive capacity (i.e., total capacity of all disks in the system) or "effective" capacity (i.e., available space after parity and the like). For normal file-sharing use, 32 GB of RAM are likely to be adequate. If you're running lots of apps/jails/VMs, it might not be.
Old general rule was 1GB RAM for each 1TB of storage. However, what's more true is actually that ZFS makes use of your RAM very well. So the more you have, the better. But if you can live with a bit more latency in your I/O (fetching data on drive is far slower that RAM). Then you can continue with your 16GB.
VMs and Apps not included in the reasoning above.
VMs and Apps not included in the reasoning above.
So I can sit with the 16GB and be completely fine? But have the option to up the RAM to 32GB?
Yes. you can. However, if you upgrade to more RAM. Your experience will be better. As ZFS will happily put that RAM goodness to good use. But as I said. If you're happy with your performance now, and find what you've got now acceptable. Then you don't have too change anything per se.
But again, if you use Apps, VMs etc etc. Then your needs might very well exceed your 16GB on hand.
winnielinnie
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Personal anecdote here. My system has 32 GiB of ECC RAM, used primarily for archiving, file access, and large/batch downloading and seeding. I have 4 jails, one of which runs 24/7 seeding Linux ISOs. No VMs. No dedup. Mirror vdevs only. No special vdevs. 16 TiB usable capacity.
It was running smoothly with only 16 GiB of RAM, even before I doubled the memory.
From FreeNAS 11.x to TrueNAS Core 13.0-U5.3.
Speaking of low resource systems...
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I use it only as a backup server and don't regularly access the data for normal use. I guess I am fine. Besides that, my internal Gigabit LAN seems to get fully used when I go to copy or paste to the server. The only thing I need to fix now is having it be my own personal "Google Cloud". Which is a whole other subject. Just have to sit and have the run to do it.
