Raid Z2 4x3TB + 2x2TB

[Alex Kohler]

I am thinking if adding 2x2TB WD Green drives to to my zpool. I currently have 4x3TB WD red drives in my NAS in a RAID Z2. My question is am I taking a major risk at losing data by adding the, two disk, mirrored Vdev to my zpool. I would gain 2TB of storage for a total of ~7TB which is much needed. Someone had recommended this option in one of the forums to me and I wanted a second opinion. I also watched Cyberjock's PowerPoint and see that it is definitely possible but is it advisable?

I know that I need to disable the intellipark feature on the WD Green drives to use them in a NAS.

My plans for the future would be to replace the 2TB Green drives with 3TB Red drives one at a time, and grow the array to ~10.5TB.

 

[cyberjock]

There's no risk. It's just a bit abnormal. Note that for home users this is a fine way to add disk space. If you were a company I'd call you silly for doing it, but at home it's not a big deal. Just realize that you now have 2 vdevs you need to keep from failing. ;)

 

[Alex Kohler]

There's no risk. It's just a bit abnormal. Note that for home users this is a fine way to add disk space. If you were a company I'd call you silly for doing it, but at home it's not a big deal. Just realize that you now have 2 vdevs you need to keep from failing. ;)

I do run a small computer business and store image backups, when doing full re installs for customers, on the NAS. I store the backups for a few weeks too just in case something goes wrong and they are needed. I am almost tempted to just buy 2 more 3TB drives, backup my data to a external, format the whole thing and do a RAIDZ2 with 6x3TB WD RED. I know that would be the preferred way but I am tight for money and have the 2TB disks now. If I go ahead and add the 2x2TB disk to the Zpool I am stuck in that configuration unless I reformat down the road which would be much harder than right now when I am just setting everything up. Is it that inadvisable to run Z2 in a 4x3tb+2x2TB?

I am crazy about maintenance and checking temps and S.M.A.R.T reading. I have setup S.M.A.R.T and IPMI email notifications, and tested that everything is working. I also setup [FreeNASTempReport](http://sourceforge.net/projects/freenas-tempreport/) so that I can monitor temps from my main workstation quickly and easily. Do you think that with regular maintenance it would be a good idea.


On a side not your Powerpoint was Godsend in helping to get a grasp of what is going on in FreeNAS. Thanks for the hard work.

 

[cyberjock]

It's not inadvisable, it just results in less than ideal performance. That is to say, you might not get full speed nonstop. For home users that's not a big deal as home users aren't taxing enough to make that matter at all.

The 6 disk RAIDZ2 would be "better" and you could upgrade the 2TB to 3TB later to get more disk space.

It's the proverbial "1/2 dozen of one and 6 of the other". Ideally I'd do 6 disks per vdev that are raidz2, so if you are really wanting to look at long-term options I'd do a 6 disk RAIDZ2 now and then later add 6 more disks as a RAIDZ2. Just make sure you plan ahead on buying those 6 disks. ;)

 

[gpsguy]

In the other thread, it sounded like you hadn't built the server yet and were considering RAIDz1 for 4x3Tb drives. And, you had a pair of 2Tb drives that you might use.

My suggestion (in the other thread) was to do what cyberjock said below.

The 6 disk RAIDZ2 would be "better" and you could upgrade the 2TB to 3TB later to get more disk space.

 

[Alex Kohler]

I had not built it yet. I started the build the day after I strated the thread.

I think one important piece of information that I left out is that I am not able to use the 2x2tb drives until I copy the data onto the new NAS because they are where I'm currently storing the data in a small cheap raid box. So I have to add a second Vdev, I cannot start with all 6 drives.

I was considering RAIDZ1 but thanks to your advice I did not choose Z1. I was actually starting this thread because of your suggestion. I just wanted a second opinion. Thanks.