[Discuss] Adventures in N40L Land

[tmetro-blu at vl.com (Tom Metro)]

Richard Pieri wrote:
> Tom Metro wrote:
>> I'm assuming the 250GB disk is not physically mounted in the RAID cage.
> 
> It is so mounted.  There really isn't space inside the chassis for more
> disk than that without blocking airflow.  It's really that tight in there.

Interesting choice that they'd ship it with an OS drive and have that
use up one of the RAID slots, while adverting it as a 4-bay file server.

So if you left the OS drive in one of the bays, why bother changing the
SATA port it is connected to?


>> There is a drive bay for a user supplied optical drive?
> 
> Yes.  It's a 5.25" bay with a removable panel on the front.

Presumably the OS drive could be mounted there. You could even stick it
in a trayless bay:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817998031


> For Tom:
> http://sidehack.gweep.net/~ratinox/02-13-12_2156.jpg
> The drive cage is easily visible...  The left-most drive slot had the system disk.

Thanks. That answers some of my other follow-up questions.


> There are two problems with
> mixing vendors.  The first is block counts.  Two different models of
> "2TB" disks may have different numbers of usable blocks.  This adds a
> layer of complexity to the setup.

Sure, they will be different, but the actual size difference will be
minor, and the Linux MD driver seems to automatically select the smaller
of the two as the max size for the set. I have one or two mixed vendor
sets and didn't need to do anything to account for it.

mdadm man page says, "...the smallest  drive  (or  partition)  sets  the
 size, though if there is a variance among the drives of greater than
1%, a warning is issued."


> The second is block size: 0.5K blocks
> vs. 4K blocks.  Mixing these may or may not be problematic.

You're referring to the Western Digital "Advance Format" drives? I don't
have any direct experience with these, but yeah, I could see that is
potentially a problem. I'm not sure if it is something you need to
account for at the RAID driver level (it has a default chunk size of
64K, which should be aligned with either block size), the partitioning,
or just the file system.

 -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/