Best Practices for Volume Layout with 4 4TB Hard Drives?

[David R]

So based on prior recommendations I decided to bite the bullet and return the WD Green Drives and get WD Reds.

I have a quantity of 4 - 4TB hard drives. I have backups so I am only concerned with the possibility of a single drive loss and am looking for good performance for regular file operations.

I was leaning towards a RaidZ configuration but it looks like some people in various posts recommend 5 drives for that:

Others seem to lean towards a mirror configuration with 4 drives:

And others recommend RaidZ2 - but that allows for 2 drives to be lost at the expense of some performance which isn't really what I am looking for.

I'm still not real clear on mirror vs stripe but am looking for any input.

Thanks

 

[Spearfoot]

Mirrors will give slightly better performance than RAIDZ2. Either way you'll only have 50% space efficiency. If performance is most important to you, use mirrors.

 

[David R]

Mirrors will give slightly better performance than RAIDZ2. Either way you'll only have 50% space efficiency. If performance is most important to you, use mirrors.

Will using Mirrors allow me to sustain 1 disk failure though and is that better than using RaidZ with 4 disks?

 

[Spearfoot]

Yes. Actually, it will allow for 2 drives to fail... as long as they're the right drives. With 4 drives in a mirrored topology, you'll have 2 drives in a mirror + 2 drives in a mirror. You can lose 1 drive in each of the mirrored pairs. But you will lose your pool if you lose both drives in either mirrored pair. Which points out the advantage that RAIDZ2 has over mirrors: you can lose any two drives in a RAIDZ2 configuration and not lose your data.

 

[Bidule0hm]

What do you want to put on those drives? movies? VMs?

 

[David R]

What do you want to put on those drives? movies? VMs?

Mainly for Plex - so media including movies, photos as well as music. Some users may also be using it for general file storage. I'm not overly concerned about drive loss as I have a daily backup using Arq to Amazon Cloud.

 

[Bidule0hm]

Ok ;)

And what network speed do you have? 1G? 10G?

 

[David R]

Ok ;)

And what network speed do you have? 1G? 10G?

Both LAN and WAN are Gigabit (1G) - 10G LAN for home use I could only dream of... =)

 

[Bidule0hm]

Ok, so even a RAID-Z2 will be more than enough given your usages, don't worry about performance, worry about data integrity ;)

 

[Robert Trevellyan]

I was leaning towards a RaidZ configuration but it looks like some people in various posts recommend 5 drives for that

Ignore the recommendations for having an 'optimal' number of drives for a given vdev layout, and focus on your requirements and risk tolerance. If you went with RAIDZ2, you would have much greater reliability but only 2/3 the storage. The question is, which is worth more to you?

 

[adrianwi]

Whilst most people here will advise against RAIDZ1, if your data is backed up and/or could easily be replaced (e.g. Movies) then I don't see the problem using it. I ran a Netgear NAS (in RAID5) and then FreeNAS with just 1 parity disk for a number of years without any problems.

 

[fta]

Use mirrors. Resilvers will be faster. You'll have more IOPs, which you don't really need right now, but if you ever do, they're there. It's also way more flexible for expanding the pool if you ever need to do that. The only drawback for your case is it's not as space efficient as Z1.

 

[Robert Trevellyan]

So, there you have it. Use mirrors, or RAIDZ1, or RAIDZ2.


Seriously, you need to understand how they differ, then pick the one that makes sense for you.

 

[Mirfster]

Aww just make each one its own vDev. Call it "RaidZRussianRoulette"...

/Joking, never ever ever ever do this.....

 

[Bhoot]

I would vote for raidz2. If data isn't important a raidZ1 will be sufficient but yes with that choice chances are you will lose all the data you hold.