pschatz100
Guru
- Joined
- Mar 30, 2014
- Messages
- 1,184
You are way overthinking all of this.
You say you are concerned about the safety of your data. For your NAS, stay with NAS drives. WD Red, Seagate IronWolf, Hitachi Deskstar NAS are all good. Keep in mind, however, that 7200 rpm drives run a little hotter than 5400 rpm drives. I would stay with 5400 rpm drives. Definitely do not use WD purple drives - they are designed for a completely different purpose. It is not a matter of read/write speeds. For your stated purpose, disk performance is a non-issue.
You can replace your failing 3tb drive with a new 6tb or 8tb drive. Think about how much capacity you will need over the next 3-5 years, and choose accordingly. When you can, purchase a second drive and upgrade the mirror. That will solve your capacity problem on the 3tb mirror. Keep the good 3tb drive for later. Then, if you want to upgrade the 2tb mirror, you can use the 3tb drive from before, plus another new disk.
There is nothing inherently wrong with using two mirrors, although I think a 4 disk RaidZ2 is better because all your storage is in one pool and ANY two drives can fail before the pool is degraded. But, as you pointed out, you need all the disks up front in order to do that. I run a 4 disk RaidZ2 system at home, and I think it is a good balance between cost and data safety.
You have backups of your critical data, don't you? Mirrors and RaidZ2 are not a replacement for a proper backup strategy.
You say you are concerned about the safety of your data. For your NAS, stay with NAS drives. WD Red, Seagate IronWolf, Hitachi Deskstar NAS are all good. Keep in mind, however, that 7200 rpm drives run a little hotter than 5400 rpm drives. I would stay with 5400 rpm drives. Definitely do not use WD purple drives - they are designed for a completely different purpose. It is not a matter of read/write speeds. For your stated purpose, disk performance is a non-issue.
You can replace your failing 3tb drive with a new 6tb or 8tb drive. Think about how much capacity you will need over the next 3-5 years, and choose accordingly. When you can, purchase a second drive and upgrade the mirror. That will solve your capacity problem on the 3tb mirror. Keep the good 3tb drive for later. Then, if you want to upgrade the 2tb mirror, you can use the 3tb drive from before, plus another new disk.
There is nothing inherently wrong with using two mirrors, although I think a 4 disk RaidZ2 is better because all your storage is in one pool and ANY two drives can fail before the pool is degraded. But, as you pointed out, you need all the disks up front in order to do that. I run a 4 disk RaidZ2 system at home, and I think it is a good balance between cost and data safety.
You have backups of your critical data, don't you? Mirrors and RaidZ2 are not a replacement for a proper backup strategy.