Need advice/opinion on planned pool/drive setup

TrueNAS General
1

Hi there,

I am a Drobo5N2 user and after being abandoned by them I am very nervous about losing my data to a proprietary storage system. I have decided to go open-source this time and build a DIY NAS with the Jonsbo N3 case.

I have been reading up on TrueNAS/ZFS and the importance of planning the pool/vdevs in advance. In an ideal world I would create a vdev with 8 10TB disks in RaidZ2 and utilize all the drive bays in my case. This should last me a very long time. Then in the future if I am running low on storage I could add a pci-e HBA and attach an 8-bay JBOD enclosure (like the QNAP TL-D800S) creating an identical vdev as the first one.

However, this is not possible for me in practice as I have nowhere to transfer the data on my Drobo5N2. I have 4 WD Red Plus 10TB drives in the Drobo (the fifth bay is empty) and I plan on getting 4 more for the new NAS that I am building. Considering the cost of the rest of the build, I don’t have the budget to buy more drives at the moment.

Would it be just as good if I build 4 disk raidz1 vdevs instead? This way I could build the first vdev with the new disks and transfer all the data from the Drobo and then use the 4 disks from the drobo to build a second vdev. In the future I could do the same thing with the JBOD enclosure, buy the disks 4 at a time.

Does this put me at a greater risk of data loss? From what I have read online people recommend raidz2 if the number of disks are between 8 - 12 because the resilver time is too long and there’s a high chance of another disk failing during the process. Based on that I feel like a small 4 disk vdev should be fine with raidz1 (raidz2 would provide the same amount of usable storage as a mirror in this case which is not very economical for me). However, the ZFS Primer in the TrueNAS documentation states that “RAIDZ1 is not recommended for drives over 1 TiB in size”

TL;DR: Is an 8 disk (10TB each) RAIDZ2 vdev much better than two 4 disk (10TB each) RAIDZ1 vdevs in terms of data protection and performance?

2

Hello and welcome to the forums.

No not really. RAIDZ1 is often discouraged for most setups in which you really care about your data. Z2 is often the sweet spot to give you that extra level of protection.

Indeed it does as Z1 allows you to lose only one disk without data loss however Z2 allows for two drives to fail without data loss.

I see your logic but I’d still say stick to Z2. Having be a drive fail at some point in your NAS is likely therefore you don’t want to be panicking when that day happens because if you lose another all your data is gone so save yourself that misery and go Z2.