WD NAS diskless cabinet

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    I wonder if someone here could answer a question about this NAS? I have  
just purchased the four bay diskless version of this hardware and have  
separately bought two WD RED hard drives (specifically for NAS) to go with  
it. Will it operate with only two of the four bays filled? I plan to fill  
the bays eventually but not immediately. There is a two bay version  
available which I assume works normally.


Re: WD NAS diskless cabinet

Bob Leon wrote:
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Second column from the left. My Cloud EX4 ?


     RAID 0, 1, 5, 10; JBOD & spanning

JBOS allows usage of independent disks. From
one to four of them.

Spanning allows the four drives to be treated as
one logical volume. If any of the four drives
fail, the "span" is dead. Not a good idea.

RAID 5 with four drives, relies on XOR parity
for protection. If one of the four drives dies
or is pulled from the machine, the array continues
to run. When the drive is eventually replaced
with a blank drive, selecting a "rebuild array",
recomputes the necessary parity pattern, to bring the
array up to full strength (from a protection
point of view).

RAID 0 is for speed. If you RAID 0 with four
drives, the four drives are interleaved. Again,
like the span, very unreliable. A single drive
failure, means the "stripe" is dead. The difference
between RAID 0 and span, is RAID 0 reads off all
four drives in parallel (4x speed), while span reads
from only one drive. (The span does not interleave
the data.) In the span, which drive responds,
depends on what part of the spanned volume you're


In summary, you have every possible operating
mode available in that column. Any where from
one drive to four drives can be used. Not all
the storage choices are equally good, from
a reliability standpoint (as disk drives wear
out, in as little as one year).

If you bought a different product, give the
exact model number for more info. WD makes
multiple NAS products, and as the page above
shows, they're all different.

If a model had only RAID 5 as a feature, the
minimum number of drives would be three drives.
And it's not recommended to run three drive
RAID 5. Run four drive RAID 5 instead. Fill
the box up. Over the years, there have been a
number of tales about three drive RAID not behaving
properly. And as a superstition, I now recommend
four drive RAID5 config as a minimum setup. Because
the average company selling these things, seem to
get that one right.

If your only copy of files are on the NAS, that
is a single point of failure. If you spanned,
maybe you have a real mess for a data recovery
situation. Basically, the bigger a storage
setup you create, the more disks you end up
buying. As now you need drives to store backups too.

I've even had some people comment, that when they
loaded DVDs onto a NAS, they would *never* recover
the data - neither choosing to backup, nor load
the DVDs ever again. Some setups have so much data,
the people who own them cannot stand the idea of
spending days repairing the thing. If you make that
call, of having only a single copy of the data as
stored on the NAS, I wish you luck :-)


Re: WD NAS diskless cabinet

On 7/20/2015 10:43 AM, Bob Leon wrote:
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The wild surmise would be that the box should work with two drives but if  
you want any sort of data safety with only two drives you'd need to use  
RAID 1 (striped) which will result in a total storage capacity equal to  
that of a single drive i.e. put in two 6tb drives and you'd see a total  
capacity of 6tb instead of 12tb.

Here is a succinct reference on RAID setups:


but you'd probably do better off going to WD to see what they say about it.  
Surely they have a manual for your unit online.

FWIW, I use a Drobo 5-drive cabinet because it removes all of the anguish  
involved in setup decisions such as you are facing. The only decision left  
to you is 'safe'(losing one drive's worth of storage) or 'double-safe'  
(losing two drive's worth). Everything else is automatic and invisible.

Re: WD NAS diskless cabinet

John McGaw wrote:
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So from that article, the possible sequence is:

1 drive - no substantial protection (same as for JBOD)
2 drive - mirror (has capacity of a single drive)
3 drive - RAID 5 (one drives worth is parity)
4+ drive - RAID 5 (one drive redundant), RAID 6 (two drives redundant)

The Wikipedia article has the nice pictures (from the first nice
tutorial article someone made), showing the parity pattern. It's
distributed, so no drive has all the parity.



It's important on systems like that, when an array enters
"degraded" status, that the equipment can show you graphically,
which drive needs to be replaced. It can be quite a pain
otherwise, to figure it out (pull drives, look at serial numbers,
and so on).

I would at least put drive label information on the outside
of the NAS, on a per-tray basis, to reduce the need to look
at the drive labels all the time.


Re: WD NAS diskless cabinet

On 7/21/2015 6:15 PM, Paul wrote:
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Or I guess one might consider RAID 10 (striped/mirrored) with four drives  
but I don't know what the path from two drives might be other than painful  
and probably involving external storage for the rebuild.

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