Re: Docs and operation of RAID10, size limitations on 0.90

Richard Michael wrote:

Hello list,

I'm building a new system with 8 disks, in two RAID5 arrays of 4 disks
each, and a RAID1 array across them.  (Then LVM2 on top of the RAID1
array.)

I approached it this way for two reasons:

1/ It feels "cleanest"; in the sense that it's not a special case, it's
just RAID1 with two devices, which happen to be RAID5.

2/ I have a particular usage in mind: I need to be able to split the
mirror and remove half; return it later and resync.  Therefore, I want
to know which disks comprise which halves.

However, I'm rethinking toward RAID10.  However, I can't find much
documentation about layout, etc.  I believe this was recently discussed
on the list.


Can someone with RAID10 experience enlighten me?  Can it be cleaned
split, half moved to another host, or rejoined with the first half, etc.
How about performance?  (Not a huge issue, but it is better than nested
arrays as I first considered?)
  

10,f2 read performance is very good, write performance is okay. AFAIK 
you can't do a split, the object is to spread head motion and improve 
performance.

Aside, I'd like it to be bootable.  I was told grub only supports
booting from 0.90 superblocks, but that 0.90 has a 2TB limitation?
Meaning, I need /boot with 0.90 and another partition (LVM) with a 1.0
superblocks?
  

I usually create a 100MB or so partition, raid1, on my drives and boot 
off that using 0.90 superblock. The rest of the storage can be anything 
you want.

-- 
Bill Davidsen [off-list ref]
  "Woe unto the statesman who makes war without a reason that will still
  be valid when the war is over..." Otto von Bismark