Best practices

[creekmor]

Just some background; I am in the process of learning and planning my build. I am also still in the process of reading the manual so please excuse my ignorance.

What is the best storage scheme if data protection is the number one priority?

Given 6 drives, how would you organize them for maximum redundancy?
6 in a mirror? 5 in a mirror with one dedicated to snapshots? 4 mirrored for data and 2 mirrored drives for snapshots?

I don't really care about the performance loss associated - I just want the smallest chance possible of losing my data. I have aproximately 300GB of critical data and I'm considering 3TB drives.

I imagine there are some other trade offs with going this route and I welcome your input.

Thank you!

 

[Jailer]

With data protection being #1, whatever amount of drives that fits your budget and storage needs in a RAID Z3 configuration. Couple this with a good backup strategy and you should have little chance of losing your data.

 

[Bidule0hm]

With 6 drives the most protection will be a mirror of 6 but that seems a little bit overkill

I confirm what Jailer said in his post, go with RAID-Z3.

And don't forget: a RAID is not equal to a backup. If you have highly critical data you need a separate backup.

 

[gpsguy]

One of the sweet spots is 6 disks in RAIDz2.

And, like BiduleOhm said, RAID <> backup. You might want to buy a couple of 1TB drives, hang it off one of your clients, and use a "sychronization" program to backup your 300GB of critical data to these drives.

 

[BigDave]

What is the best storage scheme if data protection is the number one priority?

There's a theme developing from the responses you are getting...
backup, backup, backup :D ;)

 

[creekmor]

I keep hearing this, but how are mirrored drives not a "backup"? Are all the drives not exact copies?

I'm on board with the fact that single point of failure Raid5/Z1 is not a backup. Why is a mirror lumped in with parity based Raids?

What makes it so special to copy off to an offsite location? Is data magically 100% safe once it is off the evil NAS?

 

[creekmor]

For the record, I appreciate everyone's replies but I'm just a little miffed.

 

[Bidule0hm]

The purpose is to not have a single point of failure. Let's say the PSU fail and kills all the drives; RAID or not if you don't have a backup you're screwed. (As an aside it's a pretty good reason to why to buy a good quality PSU...).

And if you can, an offsite backup is perfect because even if there is a fire/tornado/aliens... you still have a copy of your data.

 

[danb35]

The reason that "RAID is not a backup" is because it does nothing to protect against your destroying your data (e.g., by deleting it). The most data-secure use of six disks would be a six-way mirror (ZFS supports n-way mirrors, for arbitrarily large values of n), but that would be extremely wasteful of disk space. A six-disk RAIDZ3 would be very secure, and would tolerate the loss of any three disks.

 

[creekmor]

The reason that "RAID is not a backup" is because it does nothing to protect against your destroying your data (e.g., by deleting it). The most data-secure use of six disks would be a six-way mirror (ZFS supports n-way mirrors, for arbitrarily large values of n), but that would be extremely wasteful of disk space. A six-disk RAIDZ3 would be very secure, and would tolerate the loss of any three disks.

Isn't that what snapshots are for? Recover files in case you derp out and delete them?

 

[gpsguy]

For the OP, this is why I suggested a couple of smaller hard disks that your could rotate out for backup.

I have a Vantec EZ Swap 4 3.5" Aluminum Removable Trayless SATA Hard Drive Rack - http://www.newegg.com/Product/Product.aspx?Item=N82E16817986001 in my primary Win 7 desktop. I use it for some of my backups.

And if you can, an offsite backup is perfect because even if there is a fire/tornado/aliens... you still have a copy of your data.

 

[creekmor]

The purpose is to not have a single point of failure. Let's say the PSU fail and kills all the drives; RAID or not if you don't have a backup you're screwed. (As an aside it's a pretty good reason to why to buy a good quality PSU...).

And if you can, an offsite backup is perfect because even if there is a fire/tornado/aliens... you still have a copy of your data.

Makes sense. However, if I'm attacked by aliens I don't know if I'll care that much about my data anymore ;)

I guess I should have described my setup a little better. The data in question currently resides on my main desktop PC in a software mirror that is backed up every week or so to an external USB drive.

I was hoping for the NAS to be a yet another layer of protection that would be more fault tolerant than the other two.

 

[Bidule0hm]

It will be more fault tolerant, but (sadly) it will not be bulletproof :D

 

[Ericloewe]

At this time, I'd like to point out that it seems that some reading of Cyberjock's guide is in order.

There's no such thing as a drive dedicated to snapshots (though you could replicate to a separate one-drive pool, it's not a good idea in any way).

 

[creekmor]

At this time, I'd like to point out that it seems that some reading of Cyberjock's guide is in order.

There's no such thing as a drive dedicated to snapshots (though you could replicate to a separate one-drive pool, it's not a good idea in any way).

This one?
https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/

I read through it a while back but I probably need to read it again. Thanks for the suggestion

 

[Ericloewe]

This one?
https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/

I read through it a while back but I probably need to read it again. Thanks for the suggestion

Yeah, that one.