Backing Up Strategy - Attaching/Detaching a drive to a mirrored array?

[angelkiller2]

So I want to know if this is possible and whether or not it's a good idea.

So let's say I have a two drive mirrored array. Can I attach a third drive to the array, sync all the data so it becomes a three drive mirror, then detach the third drive so I store it separately as backup?

Would this work? Is it a terrible idea? (And if so why is it terrible?)

Also, are there any other backup strategies I should consider for offline/powered off backups of a mirror array?

I know the question is a little vague, but I'm trying to figure out if the idea is even worthy of attempting. Thanks.

 

[snaptec]

Plug it in, configure it as a separate pool, do a zfs replication, put it out.
From time to time plug it in and replicate the snapshots.
Not ideal (from time investment state) but works.


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[Arwen]

@angelkiller2,
Yes, you can detach a mirror, (even if it's a 2 way mirror). It may not be possible from the FreeNAS
GUI or CLI, but it's possible from a FreeBSD shell using zpool split.

Note that this will also work if you have more than 1 Mirrored vDev. It simply detaches more disks.

As for backup strategies, if the amount of used storage is less than the size of the backup disk then
you can store multiple backups on the backup disk. For example, I use my 8TB backup disk in a
single disk pool to backup a 8TB data pool, which has only 2TB used at the moment. After every
Rsync backup, I create a snapshot on the 8TB backup disk. Thus, I can go back in history if I want.
As I collect too much used in the snapshots, I simply destroy the oldest backup snapshot until I have
enough space for the new backup.

 

[angelkiller2]

Plug it in, configure it as a separate pool, do a zfs replication, put it out.
From time to time plug it in and replicate the snapshots.

@angelkiller2,
Yes, you can detach a mirror, (even if it's a 2 way mirror). It may not be possible from the FreeNAS
GUI or CLI, but it's possible from a FreeBSD shell using zpool split.

Note that this will also work if you have more than 1 Mirrored vDev. It simply detaches more disks.

Are either of these methods better than the other? I'm leaning on adding a third disk as a seperate pool and doing a zfs replication only because I can do it from the GUI.

Not ideal (from time investment state) but works.

Why is that method not ideal? And is there a better solution? My goal is to back up my mirror to another drive that I can remove from the machine.

As for backup strategies, if the amount of used storage is less than the size of the backup disk then
you can store multiple backups on the backup disk. For example, I use my 8TB backup disk in a
single disk pool to backup a 8TB data pool, which has only 2TB used at the moment. After every
Rsync backup, I create a snapshot on the 8TB backup disk. Thus, I can go back in history if I want.
As I collect too much used in the snapshots, I simply destroy the oldest backup snapshot until I have
enough space for the new backup.

Is this simply using snapshots? I only ask to clarify. My overall goal is to back up my mirror array to a hard drive that I can store offline / away from the machine. I will use snapshots on the machine, but I also would like to have offline backups.


Thank you both for your answers.

 

[Arwen]

Are either of these methods better than the other? I'm leaning on adding a third disk as a seperate pool and doing a zfs replication only because I can do it from the GUI.

A separate pool is better than a 3 way mirror with split. This is because you can add
other things to the backup pool. Or eliminate certain things from the backup pool.

Using the GUI to perform or schedule the replicate should be okay.

...
Is this simply using snapshots? I only ask to clarify. My overall goal is to back up my mirror array to a hard drive that I can store offline / away from the machine. I will use snapshots on the machine, but I also would like to have offline backups.
...

Your goal and mine are similar. I've got 2 backup disks, an 8TB for all and a 750GB for all except media.
(The 750GB is a left over from my old media server, so I had it available). Both my backup disks are stored
in anti-static baggies, then in Seahorse hard shell, water proof, plastic cases. After a backup, the current gets
taken off-site and the off-site one comes home with me.

I don't use replication for the backups. I use Rsync since I intend to keep multiple copies on the 8TB. But,
using ZFS replication should work fine. There is something to be said for KISS, (Keep It Simple, S...).

Later I will likely buy another 8TB, (or larger), and add it into the rotation.

 

[Stux]

I use automated replication with non-delete of snapshots. Haven't had to solve the issue of how to automatically delete the oldest snapshots yet.

As Arwen said, the benefit of replication/rsync is you can have more on the drive than just a split mirror.

 

[angelkiller2]

A separate pool is better than a 3 way mirror with split. This is because you can add
other things to the backup pool. Or eliminate certain things from the backup pool.

Using the GUI to perform or schedule the replicate should be okay.

Good to hear. I will most likely go this route.

Your goal and mine are similar. I've got 2 backup disks, an 8TB for all and a 750GB for all except media.
(The 750GB is a left over from my old media server, so I had it available). Both my backup disks are stored
in anti-static baggies, then in Seahorse hard shell, water proof, plastic cases. After a backup, the current gets
taken off-site and the off-site one comes home with me.

This is essentially what I'm trying to create. My primary array will be a three drive mirror. I will connect a fourth drive (of equal size), replicate the data, then remove the drive. I will do the same for a fifth drive. Both the fourth and fifth drive will be stored offline / remotely and I will redo the replication process every so often.

Thank you for the input.

I use automated replication with non-delete of snapshots. Haven't had to solve the issue of how to automatically delete the oldest snapshots yet.

As Arwen said, the benefit of replication/rsync is you can have more on the drive than just a split mirror.

I see, thanks. I think I'm going to go this route.

 

[Arwen]

...
This is essentially what I'm trying to create. My primary array will be a three drive mirror. I will connect a fourth drive (of equal size), replicate the data, then remove the drive. I will do the same for a fifth drive. Both the fourth and fifth drive will be stored offline / remotely and I will redo the replication process every so often.
...

Using more than one off-site backup disk is a good solution. As money or importance
increases, you can always add another disk into the rotation. Or perform more frequent
backups.

As I said, I use an anti-static baggie and hard shell case for storing the off-site disks. In
theory, you can use just one hard shell case for the transportation of the disk to off-site.
But my storage locker is not setup for safe disk storage, so I bought 2 of the cases. The
Seahorse ones I bought are about $23 US, (without shipping). Pelican cases are similar
in price.

 

[angelkiller2]

As I said, I use an anti-static baggie and hard shell case for storing the off-site disks. In
theory, you can use just one hard shell case for the transportation of the disk to off-site.
But my storage locker is not setup for safe disk storage, so I bought 2 of the cases. The
Seahorse ones I bought are about $23 US, (without shipping). Pelican cases are similar
in price.

I had never really thought of a case for the hard drive until I read your post. It's a good idea though, a relatively small cost for extra data protection, which is the ultimate goal after all. I will get cases once I have everything set up.

I'm still in the initial setup / configuration phase. Shameless plug, but I'm having a performance issue. Basically CIFS is terrible on Linux machines and NFS is terrible on Windows.

 

[Arwen]

I had never really thought of a case for the hard drive until I read your post. It's a good idea though, a relatively small cost for extra data protection, which is the ultimate goal after all. I will get cases once I have everything set up.
...

In my case, the data requirements were modest and I was able to get a single disk that could
store the entire pool. Thus, my choice of case was for 1 x 3.5" hard disk drive. Plus, it's large
enough for some CD, DVD, or Blu-ray disc backups, (in sleeves, not jewel cases).

If you do get a hard shell case, look to the future a few years. Would getting a slightly larger
case that can hold 2 x 3.5" disks be better? And cheaper than 2 x single disk cases?

Just a thought. Medium and long term planning is something professional Unix System Admins
do all the time, (and sometimes in their sleep .

 

[angelkiller2]

In my case, the data requirements were modest and I was able to get a single disk that could
store the entire pool. Thus, my choice of case was for 1 x 3.5" hard disk drive. Plus, it's large
enough for some CD, DVD, or Blu-ray disc backups, (in sleeves, not jewel cases).

If you do get a hard shell case, look to the future a few years. Would getting a slightly larger
case that can hold 2 x 3.5" disks be better? And cheaper than 2 x single disk cases?

Just a thought. Medium and long term planning is something professional Unix System Admins
do all the time, (and sometimes in their sleep :).

My data needs are also very modest. One goal I had when I was designing this setup was to have the offsite backups have all the data as well as be a single disk. This makes backing up and restoring simpler and since I don't have much data, a single disk backup isn't a limiting factor.

Just knowing me and how I store data, it's unlikely I will outgrow this system any time soon. So I'll stick with a single hard drive case.

Did you get the Seahorse SE56 case? I want to make sure I get the size right.

I definitely appreciate the value of planning. A long term goal is to move into some kind of Unix Sysadmin position.

 

[Arwen]

...
Did you get the Seahorse SE56 case? I want to make sure I get the size right.
...

No, I got the "Seahorse SE120 Gun Case with Foam, Small". It includes a full load of foam than you can
taylor to the disk. The case you list, SE56, seems like a 3.5" hard disk would fit. But, you would have
to add your own additional packing to keep the disk from moving around. The price for the black color
for both is about the same on Amazon.com, (50 cents more for the SE120).

...
A long term goal is to move into some kind of Unix Sysadmin position.

One thing I can tell you for getting Unix SysAdmin jobs, is have a lot of different experience:

• Scripting to automate tasks
• Understand hardware well enough to improvise repairs
• Understand software and hardware mirroring & RAID
  
• Understand volume management
• Reducing upgrade downtime by using things like alternate boot environments, (like FreeNAS does)
• Learn to love backups, and really want them to work, (a failed restore was a failed backup)

 

[angelkiller2]

No, I got the "Seahorse SE120 Gun Case with Foam, Small". It includes a full load of foam than you can
taylor to the disk.

I'll probably just stick with the SE120.

One thing I can tell you for getting Unix SysAdmin jobs, is have a lot of different experience:

• Scripting to automate tasks
• Understand hardware well enough to improvise repairs
• Understand software and hardware mirroring & RAID
  
• Understand volume management
• Reducing upgrade downtime by using things like alternate boot environments, (like FreeNAS does)
• Learn to love backups, and really want them to work, (a failed restore was a failed backup)

Interesting and helpful. I feel like I have (at least) a basic understanding ( or working knowledge) of all those topics. Sometimes I wonder if I know enough to get a junior or entry-level position. My biggest roadblock is that I have zero formal experience. I'm working on figuring out some way where I can work up to a position like that. And as always, I'm constantly learning and doing things (like this FreeNAS system as a backup solution) that teach me things.