multiple single disk vdevs and multiple disks in a single vdev performance comparison

[hellomynameisleo]

How does the performance of reading and writing compare between a setup consisting of 5 vdevs with a single drive in each, versus a single vdev with 5 drives, and how is data distributed across both setups?
Specifically, if a single file is used, would it be split into blocks and distributed across all 5 separate vdevs in the same way as in the single vdev with 5 drives?

 

[morganL]

How does the performance of reading and writing compare between a setup consisting of 5 vdevs with a single drive in each, versus a single vdev with 5 drives, and how is data distributed across both setups?
Specifically, if a single file is used, would it be split into blocks and distributed across all 5 separate vdevs in the same way as in the single vdev with 5 drives?

Both spread data across multiple drives

5WZ1 is reliable
5xSingle is very unreliable.

 

[danb35]

a single vdev with 5 drives

The only way to have a single vdev with 5 drives would be either a five-way mirror (possible, but very rare) or with parity RAID (RAIDZ1, 2, or 3). And performance is going to be very different for any of those.

 

[hellomynameisleo]

The only way to have a single vdev with 5 drives would be either a five-way mirror (possible, but very rare) or with parity RAID (RAIDZ1, 2, or 3). And performance is going to be very different for any of those.

I'm planning on using RAID0 so no parity. The way I see it going for individual vdevs single drives, is going to allow for different drive sizes or single drive pools would work too.

 

[danb35]

I'm planning on using RAID0 so no parity.

There's no such thing as a single vdev of five disks striped--those would be five vdevs.

 

[hellomynameisleo]

There's no such thing as a single vdev of five disks striped--those would be five vdevs.

never said this.
Anyways looks like I got my answer, I found a chart that showed performance for R/W increases with more vdevs in a pool and not the amount of drives in a single vdev.

 

[danb35]

never said this.

What, then? The only way to have more than one disk in a vdev is in some kind of redundancy arrangement. So if you're going to use what you call RAID0 (which doesn't exist in ZFS; it stripes vdevs, but it isn't RAID0), the only possible way to do it is with five (or however many disks you have) vdevs.

 

[hellomynameisleo]

What, then? The only way to have more than one disk in a vdev is in some kind of redundancy arrangement. So if you're going to use what you call RAID0 (which doesn't exist in ZFS; it stripes vdevs, but it isn't RAID0), the only possible way to do it is with five (or however many disks you have) vdevs.

Well 5 disks in a single vdev stripped is similar to RAID0 in that they both stripe data and are limited to the smallest drive size.
Also I notice adding more drives to a vdev doesn't increase performance so I've decided to not do a stripe and go for as many vdevs I can allowing for mixed drives sizes.

 

[Ericloewe]

Well 5 disks in a single vdev stripped is similar to RAID0

It is also a fantasy. There is no such thing. The only vdev types are single disks, n-way mirrors, RAIDZ and DRAID.

 

[danb35]

Well 5 disks in a single vdev stripped

There is no such thing. As I already said, three times. But maybe now that Eric's said it too you'll believe it.

 

[hellomynameisleo]

It is also a fantasy. There is no such thing. The only vdev types are single disks, n-way mirrors, RAIDZ and DRAID.

Did trueNAS remove the ability to stripe because I saw it in a video that you could stripe a vdev

 

[Ericloewe]

because I saw it in a video that you could stripe a vdev

Oh, if I had a buck for every wildly incorrect video out there...

 

[Arwen]

In ZFS terminology, a Stripe is across vDevs.

However, in other RAID schemes, they refer to RAID-5/6 as striping data across the disks in a RAID-5/6 set. While ZFS will stripe data in RAID-Z1/2/3 as a single vDev, it is NOT commonly referred to as a Striped vDev. It would properly be referred to as a RAID-Zx vDev.

With your insistence of no redundancy, their is exactly one ZFS option, 5 single disk vDevs, (aka Stripe).


We are not trying to be annoying, (okay, maybe one or 2 of us are), using precise wording maters in how to configure a NAS server in the manor desired. Here are 2 Resources that may be of help;

Terminology and Abbreviations Primer

We realize that new users have a lot to learn when they come to FreeNAS. There's a certain amount of confusion added to discussions when users pick random/approximate terms to describe things. I've spent a lot of time quietly trying to...

www.truenas.com

Introduction to ZFS

This is a short introduction to ZFS. It is really only intended to convey the bare minimum knowledge needed to start diving into ZFS and is in no way meant to cut Michael W. Lucas' and Allan Jude's book income. It is a bit of a spiritual...

www.truenas.com