Advice about vdev's and pools

[pmichelazzo]

Hello there,

I'm an older user from QNAP solutions but since I have new demands, I'm switching my storage solution to the TrueNAS. I build the first one with this hardware configuration:

• Supermicro MB X11SSL-CF
• 32 GB ECC memory DDR4 2400 (2 empty slots to add +32GB in the future)
• Intel i3-6300 3.8GHz
• Fantec chassi with two mini-SAS for 8 disks
• Network running over CAT-8 cables and fiber

I've install the TrueNAS in a 120GB SSD disk connected by a SATA 3.0 port and the system is running well. I added some old disks to play a bit with vdev's and pools to understand the interface and the concepts behind the system. So now, it's time to stop to play, shut down my old storage and migrate all the data to the new storage. At this point is when I'm looking for comments/advices.

On the actual scenario I have 3 kinds of data:

• backups from my day-by-day work that's include family photos, documents, code, etc;
• movies and trips footages shared on the TV using a Kodi in a RaspberryPI (I just use a shared folder to have access to this data over the network);
• surveillance data coming from the cameras installed around the house;

Doing my homework, I have the idea to build this disk set up:

• One pool to day-by-day data with 2 disks of 8TB each, vdev mirrored
• One pool to movies with 3 disks of 18TB each in a RAIDZ1 vdev
• One pool to surveillance data with 3 disks of 18TB each in a RAIDZ1 vdev

My concern about this set up is related with backups and how to grow the movies pool. Normally the day-by-day data I have routines that I wrote in bash to backup the data based in some personal rules, and put some of this data into the Amazon Glacier service. The surveillance data I don't care so much since the space in enough to have recorded about 60 days and my ZoneMinder system overwrite the old data when it's necessary.

About the movies, this is an interrogration point to me. Today I have backups into external disks. Once a month, I plug an external disk and do a rsync with the new ones (they're in different folders and never reach the size of the external disk). When the process is finished, I unmount the disk, remove from the storage and put in a special place. This is fine but since the amount of movies and footages are growing a lot (on these days, kids love to do short movies, etc), I'm expecting to have problems with the size of this vdev and with the backups.

So, the questions are:

1. Is this vdev/pools set up ok to my needs today?
2. Is this vdev/pools set up ok to be raised with bigger disks in the future, if needed?
3. There's a different way/solution to do the backups?

I hope that the people here could give me some advices with the configuration of the vdev's/pools. The disks are already into the storage just waiting the validation of the scenario above.

Thanks a lot for any tip.
Paulino

 

[albrecd]

I found this jrs-s.net blog helpful when planning out a recent upgrade to large disks.

Due to your disk size you should strongly consider avoiding RaidZ1. There are various references for why such as this ZDNet article, but the TLDR is that with drive sizes over ~1-2 TB your chances of a second drive failing during / because of the resilver process are very high. If you can add a fourth drive and use two mirrored videvs you could achieve the same storage with much better redundancy (and performance).

Mirrored videvs also make future expansion much easier since you can upgrade by replacing a single pair of disks rather then all disks, or by adding drives in pairs as additional vdevs in the stripe.

 

[pmichelazzo]

Dear @albrecd,

Thank you so much to point both articles. They're great and change a lot the ideas in my head, specially around the issues to replace disks in a RAID design. I had a one-week pain with my old storage just to rebuild a raid 5 last time that a disk dies and I don't want to have the same pain again or even worse since the disks are bigger now.

Best,