[linux-lvm] Raid 10 and LVM stripe

[Stuart D. Gathman]

On Thu, 21 Oct 2010, Fabricio Archanjo wrote:

> This box has 24x 1,5T SATA II disks, 3 controllers 3ware
> PCI-Express,6G ram memory DDR3 1333Mhz. This disks are distributed for
> each controller, 8 disks for each one.  I've done at each controller
> Raid 10 with 256k stripe size, then I've created one volume group with
> all disks and I've created one logical volume with 10G, 3 stripes and
> 256k of stripe size. I've gotten a great result with it, but i'd like
> to know what all think about it.

I didn't know that "raid 10" was shorthand for "raid 1+0".  While looking 
it up on Wikipedia, I learned about some cool features of the linux md
driver - it can stripe sequential blocks across drives, while still keeping 2 
copies on different drives, even with only 2 drives (what this poor man
usually has).  There is a "near" configuration, where copies of a block are
near each other, and a "far" configuration, where copies of a block are
on the second half (or third...) of each leg.

http://en.wikipedia.org/wiki/Non-standard_RAID_levels#Linux_MD_RAID_10

This gives many benefits of raid 10 with far fewer drives.

-- 
	      Stuart D. Gathman <stuart at bmsi.com>
    Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.