[ale] [OT] spec'ing drives for a NAS

[Phil Turmel]

Hi John,

On 09/23/2012 01:02 PM, John Anderson wrote:
> OK, thanks the whole 'green' thing is not something I ever paid 
> attention to before.
> 
> I was on the verge of ordering the QNAP TS-212 based on its reviews
> and flexibility.
> 
> http://www.newegg.com/Product/Product.aspx?Item=N82E16822107063
> 
> I was looking at drives that are listed on the QNAP drive
> compatability chart: http://web.qnap.com/pro_compatibility.asp#note9

Note #9 is significant--if you follow the link, WD points out that none
of their enterprise drives have "Time Limited Error Recovery", WD's
alternate name for Scsi Command Transport Error Recovery Control.

There is no good reason for manufacturer's to leave this option out,
except to force buyers into enterprise devices they wouldn't otherwise need.

At the moment, only Hitachi offers ERC in their desktop products.
Seagate had support through the 7200.11 family, but not after.

Deep error recovery cycles will *kill* a raid array, even if the drives
are only experiencing a transient failure.  The "linux-raid" mailing
list has numerous horror stories from people who've lost data due to
this phenomenon.

> Apparently I should avoid the 'green' one? 
> http://www.newegg.com/Product/Product.aspx?Item=N82E16822148725

I have a couple of the 2T versions of this drive.  I had other Seagates
and assumed they had continued supporting ERC.  I got burned.  I now use
these drives for non-RAID offsite backups.

> Perhaps I should get this one? 
> http://www.newegg.com/Product/Product.aspx?Item=N82E16822148337

This one should be OK.  As a desktop model drive, the NAS must have a
script or other feature to set ERC on every power cycle (enterprise
drives power up with the 7 second timeout).

> There is no color listed for the second one. Does that mean that it
> is 'blue'?

Seagate doesn't use WD's marketing color schemes, other than the generic
"green".

> On 09/23/2012 12:38 PM, simontek at gmail.com wrote:

>> Do not use a 5900rpm drive with a nas. Honestly, do not use green
>> drives for NAS. It you have them raided together,  the green drives
>> being variable to not sync, and will fail. I have seen half the
>> drives in a 20 drive setup fail in 6 months cause of that.

I haven't seen any significant early death issues with green
drives--they just don't work properly in raid arrays due to the deep
recovery cycles.  And due to deliberate removal of firmware features,
same is true of desktop drives in general.  Hitachi is still shipping
ERC support in non-enterprise drive, but they were bought by WD last
year--might not last much longer.

The drive manufacturers *really* want to take the "I" out of "RAID".

HTH,

Phil