discussion RAM for TrueNAS: How big of a difference between running 2666 vs 3200 speed? (Both 64 GB)

[QuestionAsker]

For TrueNAS Scale build, wondering the following for running 64 GB ECC UDIMM RAM:

Would a 2 x 32 GB 3200 RAM kit ($370) have significantly better performance than a 4 x 16 GB 2666 RAM ($250) kit?

For a TrueNAS to be mostly used for:

• Automated backups (from my homelab and other devices)
• Accessing large video files and music projects

Specs:

• Mobo: ASRock B550 Pro4
• CPU: Ryzen 7 PRO 4750G
• HDD storage: 5 x WD Ultrastar DC HC580 (24TB SATA) - (5 wide vdev in RAID2Z)

 

[moocow]

Not an expert in this area but for a storage box, I would just go with the cheaper memory. Sure the CPU technically supports all the way to 3200 GHz and running 4 sticks on AMD at higher speed always an issue but at 2666 GHz, I would bet $5 that it would be fine. That's $120 toward HDD. You are storing stuff not processing stuff.

 

[djbrad]

Sometimes motherboards have trouble with 4 sticks populated.

How about 2x32GB of the cheapest?

You don't game or render, so you should not see a big difference in ram speed.

 

[Izerous]

Using 2 mirrored SSD's as read/write cache would have a larger effect than the faster memory speed.

 

[lowfat]

Using 2 mirrored SSD's as read/write cache would have a larger effect than the faster memory speed.

SLOG 'write cache' only is used for sync writes. Assuming he is using a Windows machine, it would be completely useless.

For an L2ARC, it could be beneficial if his working datasets are very large. But it definitely doesn't need to be mirrored as the data is already on the drives.



As for memory, won't make any difference in terms of ZFS performance. You'll be limited by network speed anyways. I'm using 2133MHz.

Also on the topic of memory, ECC isn't a requirement like so many people were lead to believe. ZFS isn't any more susceptible to bit rot than any other filesystem. Is it mission critical data? Then by all means use it. But then you should be using it on any machine that has a copy of that data as well.

 

[Marzipan]

Sometimes motherboards have trouble with 4 sticks populated.

How about 2x32GB of the cheapest?

You don't game or render, so you should not see a big difference in ram speed.

with the speeds mentioned, it sounds like they're talking about DDR4, so trouble is unlikely. I'm curious about whether the ECC RAM would work. I mean, the RAM will, but whether it's actually being run with ECC enabled is what's questionable.