Planning a build, need some clarification

[Bidule0hm]

Biduleohm, is any of the stuff from your "Misaligned Pools and Lost Space" thread incorporated into your drive size calculator?

Not yet unfortunately, just too many things to do IRL for now. But I really want to do all of what's in the todo list as soon as I can ;)

In the mean time you can still calculate the misalignment overhead by hand I guess :P

 

[Wallybanger]

So don't. Put four 6TB or 8TB WD Reds in a PowerEdge T20 with 32GB of RAM. You'll have more than double your current storage, for about half the price.

I'm glad you think so.

If you've never experienced free space fragmentation, good for you. If you really don't see the value in combining all of your storage into a single pool, I don't know what to tell you. The ZFS designers saw quite a lot of value in that, enough so that that they created a filesystem to enable it.

...and to actually do the math on that:

• Dell T20: $180
• 32 GB of ECC RAM: 4 x $65 = $260
• 6 x WD Red 6 TB drives: 4 x $239 = $956
• Total: $1,396

You could probably even reduce the RAM to 16 GB and save $130. That will give you 12 TB, or 10.8 TiB, of accessible space, about 9 TiB usable if you follow the 80% rule. The numbers are the same whether you put the drives in RAIDZ2 or striped mirrors.

lol I just meant that I've never worked with files that were over 100gb or with software that required more than 100gb to do it's thing. My free space fragmentation issues are usually in the <10gb range :p I do see the value, for sure, but a guy needs to make sure he maintains a certain level of redundancy to ensure a z-pool failure doesn't destroy a ton of valuable data.

Wow... how are they even able to make one of those things for $180?? What's the catch? How come people aren't just using T20s? Does FreeNAS work on it? I've never been a big Dell fan.

Not yet unfortunately, just too many things to do IRL for now. But I really want to do all of what's in the todo list as soon as I can ;)

In the mean time you can still calculate the misalignment overhead by hand I guess :p

What!? I thought everything was supposed to be free and easy on the internet? I don't recall seeing "by hand" in the brochure :P ;)

 

[danb35]

I don't have personal experience, but the T20s are reported to work well. Another small budget choice is the Lenovo TS140, but it isn't quite as cheap as the Dell.

 

[Wallybanger]

Can you run me through the numbers you posted above and how they relate to RAM?

So 6*6TB drives is 36TB of raw storage. S0 about 19TB of space with ~5tb of free space. Why did you say I would have 12TB of accessible space and 9tTB of usable space? I'm assuming the 80% rule is in relation to the recommended free space... or does that have something to do with the ram? What's the difference between accessible and usable?

 

[danb35]

I was using 4 drives, not 6.

 

[Wallybanger]

I was using 4 drives, not 6.

"6 x WD Red 6 TB drives: 4 x $239 = $956"

You threw in a 6 and I missed the 4 ;)

 

[danb35]

Oops, you're right. I meant four, but obviously my fingers disagreed.

 

[Wallybanger]

Well that's a tough decision. I would definitely be saving some money on hardware but there isn't much there in the way of future expansion. Will those things run FreeNAS? The T20 mentions Redhat and Windows server but not FreeBSD.

On a side note, will 32GB of ram support 32TB of raw HD space in a RAIDZ2 config? I keep hearing this gb of ram per tb of HDD space but I'm wondering if that is more so for people who are really using the hell out of their NAS units. For 32TB of drive space and OS/JAIL/VM usage would I have to go up to 64GB of ram?

 

[Ericloewe]

keep hearing this gb of ram per tb of HDD space but I'm wondering if that is more so for people

It's a rule of thumb. Generally speaking, home users can afford to stay below 1GB/TB.

 

[Robert Trevellyan]

How come people aren't just using T20s? Does FreeNAS work on it?

FreeNAS works very well on the T20 (check my signature). Some people want more drive bays, or more CPU power.

 

[Wallybanger]

Ugh, I think I'm just going to go for it. Gonna go up to an ATX-ish case and get a SuperMicro MB. Think I can save money on the machine by getting a cheaper case.

All I have to do now is figure out how to pick a CPU.... soooo many choices :/