[Gllug] Hard disk recommendations please

[Nix]

On 3 Dec 2010, general verbalised:

> Of course adding a second drive doubles both your power consumption and 
> your chances of something going wrong ;) Having spent much of the last 
> week troubleshooting a raid on the cheap system I'm not sure those 
> "green" drives are really up to the job of being in a raid. I've 
> experienced numerous sync losses/rebuilds and a lot of sector level 
> corruption on the freeNas I built with these type of drive at the start 
> of the year despite disabling the power saving features at the start.

Interesting. I've experienced not a single problem with the half-dozen
4, 8, and 16-disk RAID arrays (mostly RAID-6) I've built using WD
GreenPower drives over the last year. Perhaps the difference is that
these were using battery-backed hardware RAID controllers? (Areca, in
case it matters, which suck quite a bit less than most of the
competition). There's been no corruption whatsoever.

Perhaps a firmware problem?

> The 3 non-raided caviar greens I run at home (which take a far heavier 
> battering) have all behaved themselves impeccably over the years. I have 
> disabled the power saving auto spindown features on these too. They run 

Oh yes, indeed --- well, it depends. The auto-spindown-all-the-way
features are horrible. The spin slowdown thing (where it does not spin
all the way down, but only to 2500rpm or thereabouts) is really very
nice, reduces noise significantly in idle periods and does amazing
things to the power consumption.

> surprisingly fast (> 80MB/s), certainly good enough to keep up with 
> domestic service on a GB LAN

Particularly if you have a RAID-5 array of four of them! 180Mb/s on the
slow part of the disk, 260Mb/s on the faster portion. I like it :)

> On balance the raided setup has caused me WAY more pain and cost me WAY 
> more time than the non-raided system with the same disks.

Weird. Personally I would never consider using non-RAID for anything at
all unless the data is a mirror of a master copy on a RAIDed
system. I've lost too much data in disk failures over the years. Even my
home systems are either RAID-1, RAID-5/6 or Flash storage rsync mirrors
of a master copy on a RAID array. (For important data, battery-back or
UPS it too to avoid disk corruption on power loss during write.)

> As for power saving these things are VERY power efficient. Generally 

Yes indeed.

> they draw about 6W so, even presuming expensive (15p/KWh) electricity it 
> would cost you less than a tenner a year to keep it on 24/7/365. If it 

When I shifted to four GreenPower drives on PCIe in my home server
rather than four aged disks of various sorts on PCI, my RAID array went
from 30Mb/s to, well, the 180--260Mb/s mentioned above, and my house
power consumption dropped by about 30%. Starting to suspend the desktop
when not in use and moving to a Soekris as my firewall shaved off
another 30% or so.

> wears out in half the time because it's forever spinning up and down I 

Nah. It's built for it. It's not as if it pushes the heads out of the
way or stops them floating, which is what damages disks when they spin
down: it can read perfectly well when spinning at lower speed, and
indeed even while spinning back up. It just can't read as fast.
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