# Boot software raid?



## chancey (Jul 13, 2010)

Coming from a background of linux (specifically fedora) its very easy to setup raid1 during the install process, but I couldn't see the same options in the freebsd installer ... is this possible?

Not as important but is UFS2 the only supported bootable OS, does the boot loader support ZFS yet - which would eliminate the need for software raid to get the same effect?


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## kpa (Jul 13, 2010)

You can convert to RAID1 after finishing the installation. I just converted my 8.1-RC2 system to gmirror RAID1 using the instructions from the handbook:

http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/geom-mirror.html

I used 
	
	



```
-b load
```
 instead of 
	
	



```
-b round-robin
```
 but otherwise followed the guide to the letter.

Worked out of the box and was much easier to setup than md raid on Linux :e


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## chancey (Jul 13, 2010)

kpa said:
			
		

> You can convert to RAID1 after finishing the installation. I just converted my 8.1-RC2 system to gmirror RAID1 using the instructions from the handbook:
> 
> http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/geom-mirror.html
> 
> ...



This is more a mirror than raid, like a replacement on failure. If I have 2 disks i'd like to see twice the read speed ... ZFS would be the ideal option but thats still a while off from what I can tell.

Never the less, a mirror option is better than no option so ill give it it go thanks.


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## aragon (Jul 13, 2010)

chancey said:
			
		

> If I have 2 disks i'd like to see twice the read speed


gmirror(8) can give you higher read performance depending on the balance algorithm you configure it to use.


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## phoenix (Jul 13, 2010)

chancey said:
			
		

> This is more a mirror than raid,



Uhm, a 2-disk mirror is a RAID1 array.  IOW, it most certainly is a RAID setup.  Why would you think it wasn't?



> like a replacement on failure. If I have 2 disks i'd like to see twice the read speed



You will never see twice the read speed from a 2-disk mirror for all workloads.  If you try to read two different files simultaneously, and the controller/software is smart enough to read each file off of separate disks, then you get the impression of "twice the read speed".  But reading a single large file, it will all come from 1 disk, and be limited to the read speed of that 1 disk.

A 2-disk RAID0 (non-redundant stripeset) would give you twice the read speed for most workloads.  But you lose the mirror/redundancy.



> ... ZFS would be the ideal option but thats still a while off from what I can tell.



You can't tell.    ZFS boot has been supported for a year or more now.  Even booting off a pool using raidz vdevs.  It's not yet part of the standard FreeBSD installer (sysinstall), but there are several how-tos available online (including one here in our How To forum) for installing manually onto a ZFS pool.  And the PC-BSD 8 installer can do this (and can even install vanilla FreeBSD).


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## jb_fvwm2 (Jul 13, 2010)

Sort of off-topic, but "is ufs2 the only"
can remind one of...

 "gjournal".  I set up
gmirror but had trouble with unexpected 
results from the command line using it, so
began using gjournal for a few disks. (the
manpage is helpful for the latter). 
(New in the works is SUJ, journalling with
softupdates).


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## SirDice (Jul 14, 2010)

jb_fvwm2 said:
			
		

> Not-quite-raid1 is "gjournal".


Not quite? How about not even close?

Journalling won't save you when a disk dies, RAID1 will.


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