How to distribute ECC RAM between two servers?

[Gerr]

I have the following sticks of ECC RAM...

 

Four 8GB Crucial Unbuffered ECC DDR3-1600 CL11

Four 4GB Hynix Unbuffered ECC DDR3-1600 CL11

 

I have the following two servers...

 

Freenas

Xeon E3-1231v3 on an Asus C222 mobo.

Plex - media on 3x3TB HGST NAS HDD's in Raidz1(ZFS), jail & metadata on a 250GB Crucial MX200 SSD

 

Windows Server 2016 Essentials

Xeon E3-1226v3 on an Asus C226 mobo

NAS - is my personal NAS using two mirrored 3TB WD Red drives.  Backed up to an external USB 6TB HDD.

NAS - is my wife's primary NAS using two mirrored 1TB WD Red drives.  Backed up to an external USB 2TB HDD.

NVR - Running Blue Iris NVR app saving data to a single 3TB WD Purple.

Client backups - running automated client backups to a single 4TB HGST NAS HDD.

Domain Controller(future) - at some point will promote this server to a domain controller, just not ready yet.

Blu-Ray Ripping & Transcoding - I will infrequently use this system to rip new Blu-Rays via MakeMKV and then transcode them using Handbrake.

 

 

I would prefer not to mix brands, so one system will get 32GB of Crucial RAM and the other will get 16GB of Hynix RAM.  

 

My initial thoughts would be to give the FreeNAS system the 32GB as it will use the extra RAM as an ARC cache.  Plus 16GB would be just under the recommended RAM for a ZFS system, that being 8GB + 1GB per TB of drive space, so 8GB(ZFS system) + 9GB(9TB of drives) = 17GB.  Plus as my media collection grows, I might upgrade the drives to a higher capacity, which would require more RAM.  While still too expensive, would love to replace the 3TB drives with 8TB drives, which would give me 16TB of usable storage and the 32GB RAM would be the exact amount of required RAM for that...8GB + 24GB.  However, I don't expect to be able to afford that for 1-2 years.

 

The type of work done by the Windows Server isn't RAM intensive, so I think 16GB would be fine there.  Not sure about if I would need a RAM upgrade when I promote it to a domain controller or if 16GB would still be fine then.

 

Thoughts/Opinions?

[porina]

I think in this use case, prioritise the ZFS demands so I agree with your thinking.

[Jarsky]

Neither will utilise all that memory anyway, so whatever floats your boat.

I

[AshleyAshes]

3 hours ago, Gerr said:

Plus 16GB would be just under the recommended RAM for a ZFS system, that being 8GB + 1GB per TB of drive space, so 8GB(ZFS system) + 9GB(9TB of drives) = 17GB.  Plus as my media collection grows, I might upgrade the drives to a higher capacity, which would require more RAM.

This is actually just a myth.  The mysterious memory demands of ZFS have been long dismissed by actual ZFS devs.  Though it persists quite strongly among a lot of NAS forums because people just reinforce myths into other people and so on.

[Gerr]

Myth or not, doesn't FreeNAS/ZFS use unused RAM as an ARC cache?

 

Plus I thought the myth was that was REQUIRED and they dispelled that down to just recommended?

[Jarsky]

ARC will do very little unless you're on a 10Gbit network and you're only accelerating the most used ~20GB.

If you want to accelerate your array, then it'd be more beneficial using SSD's to setup L2ARC - you'll have a much larger cache. Not that it matters in the slightest for a zpool of media storage - your 3 disks in a RAIDZ1 will already give you plenty of throughput. Then only time you'll see ARC performance is when you're copying between high speed storage/arrays on the local host or via a high speed link.

 

[dalekphalm]

58 minutes ago, Gerr said:

Myth or not, doesn't FreeNAS/ZFS use unused RAM as an ARC cache?

 

Plus I thought the myth was that was REQUIRED and they dispelled that down to just recommended?

Unless you're using Deduplication, the additional RAM will have negligible performance differences.

[newgeneral10]

On 8/3/2017 at 7:45 PM, Jarsky said:

ARC will do very little unless you're on a 10Gbit network and you're only accelerating the most used ~20GB.

If you want to accelerate your array, then it'd be more beneficial using SSD's to setup L2ARC - you'll have a much larger cache. Not that it matters in the slightest for a zpool of media storage - your 3 disks in a RAIDZ1 will already give you plenty of throughput. Then only time you'll see ARC performance is when you're copying between high speed storage/arrays on the local host or via a high speed link.

 

Make sure you max out your arc (ram) before you add l2arc (ssd).  l2arc is indexed in ram so it could theoretically hurt performance if you don't have enough ram first.

 

Source(s):

https://doc.freenas.org/11/zfsprimer.html

http://docs.huihoo.com/freenas/9.3/zfsprimer.html