3x3TB RaidZ1 or 4x2TB RaidZ1?

[Antioch18]

Hi, folks. I'm new to FreeNAS and ZFS and I'm planning out my first FreeNAS build.

I was wondering if there are any significant trade-offs/differences between going with 3x3TB HDs or 4x2TB HDs for a RaidZ1 array? (Other than you're less likely to have a disk failure with 3 disks vs 4 disks)

My setup will be used to store media: movies, and family photos and videos. I only really care about the photos and videos, and will likely look into getting a cloud storage account to send off snapshot/backups of these files to.

While I'm at it, I may as well ask if there are any other more efficient ways to brake up the storage pool instead of into a single zpool?

Thanks for the help,
Antioch

 

[Raymond Matos]

Well, thats not true (about the disk failure). If you do have a disk fail in a 3x3TB, the resilver time would be days, depending on how much data you had. If your machine will be on 24/7, i would consider doing a 4x2tb with a hot spare. So 5 drives in total. Also consider the smaller drives 1tb and 1.5 tb. Resilvering sucks.

As far as family photos, i would think twice about storing only on your box, unless you have it setup to create backups and have the hot spares. If you go the cheap route, no backup and no spares, only keep data you dont mind losing if a drive goes out.

You dont want to be where i am. 2 arrays of 4x2tb, with 2 drives dead. Gave up on the reslivering because of errors, so moving the important data to another disk and redoing the pool. Not too worry about it since it was all videos that can be downloaded again.

I love freenas, but just had bad experiences with some of these drives. However i run my server all the time, I store daily backups, download movies and stream to multiple devices. When the drives (WD ears) wanna work, its great. I guess you get what you paid for.

 

[Antioch18]

As far as family photos, i would think twice about storing only on your box, unless you have it setup to create backups and have the hot spares. If you go the cheap route, no backup and no spares, only keep data you dont mind losing if a drive goes out.

Yeah, the plan is to find an online backup service that I can make backups of the family photos to.

I'll reconsider going for the 2TB drives instead of the 3TB ones.

Thanks,
Antioch

 

[Raymond Matos]

One thing to consider there some new rsync online backup services popping up now. And some are cheap $20 a month for 500GIG. SO you could backup the photos to some rysnc online service.

Here are some

https://www.strongspace.com/plans
http://www.rsyncit.com/

I haven't tried it, but rsync is pretty basic stuff, so should be pretty simple to setup.

 

[paleoN]

If you are going with the 3TB drives you need 4, well 5. The 5th would be the cold/hotspare. The 4 active ones you could run as a couple of striped mirrors, a 4 disk raidz2 array or 2 mirrors with 2 zpools. The only single parity array I would run with 3TB drives would be in a mirrored configuration.

It's already been mentioned, but I'll say it again. No form of RAID is a replacement for backups, a second copy of the data on a different physical device.

 

[Antioch18]

Digging up this thread again as I'm finally getting around to setting my FreeNAS box up...

Have been toying around with getting three or four 3TB disks but unsure of what configuration to run them in.
4 disks in a RAIDZ2 or 2 striped with a mirror?

If you are going with the 3TB drives you need 4, well 5. The 5th would be the cold/hotspare. The 4 active ones you could run as a couple of striped mirrors, a 4 disk raidz2 array or 2 mirrors with 2 zpools. The only single parity array I would run with 3TB drives would be in a mirrored configuration.

Why is that? Isn't a mirrored stripe more susceptible to failure than a raidz2 array?

For example, in the striped mirror you have disks A1, B1, A2, and B2. In the event of a two disk failure you're hosed if you lose either A1 or B1 and it's mirror (A2 or B2 respectively). However, in the raidz2 scenario, you can lose any two disks and still recover.


Final question. If I have 3 disk raidz1 array, can I simply migrate it to a raidz2 array by adding another disk?

Thanks,
Antioch

 

[JaimieV]

RAIDZ2 isn't single parity - it's got two parity disks. So yes you are right that it is less susceptible to failure than a 2x2mirror, but PaleoN wasn't talking about that situation - he was talking about mirror vs RAIDZ1 with 3Tb drives.

Final question: Nope (if only!). Go read Cyberjocks' presentation about ZFS arrays at the top of the Noob forum for more info.