Few General Questions hardware etc

[Randall8686]

Hi All

 

Just a few general questions i have an unraid setup on my server working nicely so far (still getting to grips) my questions are

 

Does a SSD cache make much difference? If so i read i need two? Are hdd as cache drives going to offer anything over the standard array?

 

Does getting a extra nic make any difference when im only going to have 2/3 users with each only having gigabit connections.

 

Im using 6 x2tb drives at the moment im going to need another 6tb soon so stick with 2tb drives or mix and match a couple of 3/4tb drives?

 

Current spec is

 

Xeon e3-1226 V3

8gb eec ram

No graphic yet but thinking of doing a vm with a graphics out at some point so maybe a half decent graphics card at some point

 

Used for media server, file storage for office stuff and photos etc. Backing up laptops and the vm eventually will be used for office work and maybe some very light gaming.

 

Tia

 

 

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[JonathanM]

For the original purpose of caching new writes to the server, SSD's aren't needed. But, for the more typical current use as VM domain storage and docker appdata and image location, SSD's will make a huge difference.

 

I personally would NOT recommend running VM's on a spinner drive, and especially not on an array drive. It works, but performance is horrible compared to SSD.

 

Whether or not you need 2 is a personal choice. I'd rather use a good backup strategy than trust BTRFS mirror functionality.

 

New drives, I'd purchase at the large end of the $/TB scale. IOW, if a 2TB drive is $50/TB, a 4TB is $40/TB, a 6TB is $30/TB, and a 8TB is $40/TB, I'd get the 6 or 8TB. Larger drives = fewer connections,less power,less space per TB.

 

Network, multiple gigabit connections are a pain to get right, and really don't offer much if any performance increase in most layouts.

[Randall8686]

Thanks for the advice can i move the vm image to a ssd if i set it up now on the array drives then order an ssd and move it when i get it?


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[JonathanM]

19 minutes ago, Randall8686 said:

can i move the vm image to a ssd if i set it up now on the array drives then order an ssd and move it when i get it?

Sure! If you follow the recommended layout for shares and data locations, it will actually be pretty much automatic when you add the cache drive. If your VM lives in a share that is set for Cache:Prefer, it will happily live on the array drive until you add the cache drive, stop the VM service, and run the mover.

[Randall8686]

Ok so just got the ssd for the vm os, going to do a fresh install. Im correct in saying i set the ssd up as a cache drive even though i only want it for the os? I got a 120gb drive for a win 10 install not going to install much on it tbh a few applications about 20gb worth.

If its installed as a cache drive will the system try to use it as such ? As i really just want all 120gb just for the os drive


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[DoeBoye]

16 minutes ago, Randall8686 said:

Ok so just got the ssd for the vm os, going to do a fresh install. Im correct in saying i set the ssd up as a cache drive even though i only want it for the os? I got a 120gb drive for a win 10 install not going to install much on it tbh a few applications about 20gb worth.

If its installed as a cache drive will the system try to use it as such ? As i really just want all 120gb just for the os drive

That's the traditional way of doing it, and in most use cases, it should be fine. I started like that, but ended up moving my VM to an Unassigned Device because I was finding with large file transfers on the server, the VM's performance would start to suffer, as the cache drive was busy caching files :). With the VM on an SSD in unassigned Devices (plugin), performance was back to normal. And again, this is a very marginal use case, but I don't see any advantage to having it on the cache drive, so why not avoid any future I/O issues at the same time?

 

Now that I've gone and preached the value of having it off the Cache drive, I just thought of one scenario where it would be good to have it there :): If you only have the one SSD, I would recommend doing the traditional cache drive route, because then you'll get the benefit of a cache drive in your system (faster perceived transfers, better performing dockers if app data folder is housed there) as well as a home for your VM. You mention you only want the drive for the VM, but why not have a cache drive? If you have any mission critical files being created/transferred to your server, you can always make that share not use the cache drive... The performance difference is substantial in all other transfers, and in the performance of your dockers...

 

When you set up the VM, you can easily just dedicate 20 or 30GB to the image, and the rest of the drive is available for caching and Docker use...

Edited March 24, 2017 by DoeBoye
spelling

[trurl]

1 hour ago, Randall8686 said:

If its installed as a cache drive will the system try to use it as such ? As i really just want all 120gb just for the os drive

Each user share has a setting that controls whether and how it uses cache. Some system-created shares are cache-prefer, which means they should stay on cache once they get there, but can be on array until you get a cache disk. Any user shares you create will not use cache unless you tell them to.