# disk mirroring



## stephanelefou (Mar 26, 2014)

Hi,
I want to create a RAID1 mirror on my server, which will mirror ada1 (existing) and ada2 (new)

My server is currently setup as follows:
ada0 --> 40 GB, boot disk, usual partitions on it, no need to backup this volume
ada1 --> 500 GB (1 partition)
ada2 --> 500 GB ( identical to ada1, not installed yet)

The partition for ada1 reads:

```
root@fbsd91:/usr/home/steph/code/c # gpart show ada1
  =>       63  976773105  ada1  MBR  (465G)
           63  976773105     1  freebsd  [active]  (465G)
```

There is a howto about this but it's about mirroring ad0 and ad1:
19.4.3. Creating a Mirror with an Existing Drive.

Since I don't need to mirror any boot or swap partitions for example, which steps do I have to ignore -if any- in order to create a mirror between ada1 and ada2?

Thanks.


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## wblock@ (Mar 26, 2014)

The only difference would be which partitions are created on the new mirror.  The steps are still the same:
Back up everything.
Create mirror on new, blank drive.
Create partitions on mirror.
Copy data from old drive onto mirror.
Test.
Add old drive to mirror.  (Old drive will be overwritten, but data has already been copied onto mirror.)


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## ralphbsz (Mar 26, 2014)

Why not use ZFS?  Built-in mirroring, and nice clean administration.  It has the advantage that management of the file system and of the mirroring is integrated.


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## stephanelefou (Mar 28, 2014)

wblock@ said:
			
		

> The only difference would be which partitions are created on the new mirror.  The steps are still the same:
> Back up everything.
> Create mirror on new, blank drive.
> Create partitions on mirror.
> ...



Thanks, will try this weekend and post a follow-up.


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## stephanelefou (Mar 28, 2014)

ralphbsz said:
			
		

> Why not use ZFS?  Built-in mirroring, and nice clean administration.  It has the advantage that management of the file system and of the mirroring is integrated.



Thanks, I will consider this option if the other one do not meet my expectations.


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## wblock@ (Mar 28, 2014)

ralphbsz said:
			
		

> Why not use ZFS?  Built-in mirroring, and nice clean administration.  It has the advantage that management of the file system and of the mirroring is integrated.



If the resources, particularly memory, are available, ZFS is nice.  For low-resource machines, or when the resources are needed elsewhere, gmirror(8) is good.


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