ZFS Setup with Geli and 4k alignment

L

lockdoc

Hi there,

I want to set up a new fileserver having the following hardware:
Code: 
RAM: 8GB RAM
CPU: Intel Core2Duo 3.2Ghz
HDD: 8x 1TB Samsung Spinpoint F3
SSD: 1x Corsair 60GB Force Series 3 SATA 6GB/s

Performance considerations

So far I have heard that separating the pool from the data is better for performance.
I also heard that using whole disks rather than partition them is also better for performance (correct me if I am mistaken), so I have decided to go this way:

+ A pool consisting of 4 x Mirrors (Raid1)
+ SSD for ZIL, L2ARC, Cache/Log and the base system itself

Q1: How to best partition the SSD and should i also use zfs for the os or rather ufs?

Purpose

It should be mainly for fileserving, but will also have a couple of jails (running inside the pool), such as dns, dhcp, mysql, apache, svn (all separate jails). The pool needs to be fully encrypted with geli.

1.) Hard disk alignment Methods

I found a couple of solutions to align the disks for 4k

a) Windows Way

Code: 
gpart create -s gpt ada0
gpart add -t freebsd-zfs -b 1M ada0

b) Using gnop

Code: 
gnop create -S 4096 /dev/ada0

I also have seen a combination of them. Now I am not too sure which method to take.

Q2: Which alignment method would be best?

2.) Hard disk alignment methods with geli

How does geli fit into all this?

Q3: Do I have to do another align for geli?
 
Method A has less overhead--but maybe not signifcantly less--by not going through another GEOM device. Calling it the "Windows way" seems unfair.
 
@wblock:
So both work for pure zfs then. No offense, just called it because that's how windows does it.

So what about if I encrypt the drives with geli afterwards, how does it work with the alignment?
 
If you use geli you don't need to align with say gnop.

Assuming you labeled all disks,

Code: 
geli init -b -s4096 -l256 /dev/label/disk0
..
geli init -b -s4096 -l256 /dev/label/disk7

That -s4096 means you will be encrypting in 4096 byte blocks.

Once you geli attach all disks, this will give you /dev/label/disk0.eli .. /dev/label/disk7.eli, which you then add to zpool.

I would use one zpool for data (8 hdd) and another zpool for system. YMMV.
You may not want to use -b for geli.
 
Thanks for the answers.

Is it actually a good idea to use the SSD for both, a) the system and b) ZIL, L2ARC and Cache/Log for the data pool? If yes, how should I best partition it, in terms of how much space for what, to have a stable/performent system?

Or should I rather also separate the system and the other stuff on two separate SSD's?
 
Ok so the best would be 1 SSD for the OS, 1 SSD for l2arc and a third SSD for zil.

As I need encryption, zil and l2arc need to run on geli as well. Now here is the point where I don't know if geli will be too much overhead for zfs cache, so that performance will actually drop, even though it is on a spare SSD. Any experience with encrypted l2arc?
 
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