Re: Best way to achieve large, expandable, cheap storage?

[Robin Bowes <robin-lists@robinbowes.com>]

Gregory Seidman said the following on 20/10/2005 12:19:
> } PV:
> } /dev/md1 - 4 x 40GB drives (RAID5 - 120GB total)
> } /dev/md2 - 4 x 40GB drives (RAID5 - 120GB total)
> 
> You should at least read the following before using RAID5. You can agree or
> disagree, but you should take the arguments into account:
> 
> http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt

This was just an example configuration. My current 1TB array is RAID5 
with 1 hot spare but I'll most likely use RAID6 in production.


> } Suppose I then add a new PV:
> } /dev/md3 - 4 x 300GB drives (RAID5 - 900GB total)
> 
> You use pvcreate and vgextend to do so, incidentally.

Yes, thanks for the detail.

> } When this finishes, big_vg will contain /dev/md2 + /dev/md3 (1020GB 
> } total). /dev/md1 will be unused.
> 
> /dev/md1 will still be a part of big_vg, but it won't have any data from
> any LVs on it. You will need to use vgreduce to remove /dev/md1 from the
> VG:
> 
> # vgreduce big_vg /dev/md1

Ah, yes, forgot about that step.

Thanks for the validation of the methodology.

I'm going to give this a try on my test server (using much smaller disks!)

Thanks again,

R.
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