OT: Disk choices

Hi Andrew,

Andrew Smallshaw wrote:
> On 2010-11-17, Clifford Heath <no@spam.please.net> wrote:
>> D Yuniskis wrote:
>>> So, I'm in the market for some 1-2T drives,
>> There's effectively only three manufacturers.
>> According to my friend in the video industry,
>> the PVR is one of the main driving forces behind
>> capacity and reliability, since many PVRs record
>> continuously, sometimes two channels, while
>> sometimes playing as well - very hard on drives.
>> His opinion is that the manufacturers are leap-
>> frogging one another every month or three, so
>> which is best depends on where you buy in the
>> cycle.
> 
> That was my first thought.  I assume we're talking about consumer
> grade drives rather than enterprise units.  I've installed a few

Not a valid assumption.  :>  I'm just looking for advice
as to what to look *at* and what to *avoid*.  Though, when
these projects are finished, I'll probably take them off-line
and just use them for archival storage.

> Hitachi Cinemastar drives here, mainly for their acoustic properties
> and quoted reliabilty - the MTBF is in excess of 100 years but I'm
> not 100% sure I actually believe that.  Performance is reasonable
> on balance - it seems with AV drives you lose a little in terms of
> access time but you gain in terms of true sustained transfer rates

I think AV drives omit some of the periodic recalibration
cycles at run time.

My use is for data storage so, "in a tie", access time would
be the winner there (though neither of these apps really
beat on the drive).

> - you can read and write tens of gigbytes without them so much as
> burping.  The drives I've installed here are 500GB units but no
> doubt they have bigger models in their range.

At 500G you could still be talking PATA -- though I suspect not.
(extra credit question:  anyone know where the PATA cutoff was?)

On Tue, 16 Nov 2010 16:59:42 -0700, D Yuniskis
<not.going.to.be@seen.com> wrote:

>So, I'm in the market for some 1-2T drives,
>SATA no doubt.  I don't need speed demons.
>Rather, I would like something that is going
>to be reliable, and probably run cool (this
>makes choice of enclosure less of an issue).

If you need some degree of reliability with current consumer quality
electronics (i.e. you are not willing to pay for military/aerospace
components), I would suggest looking for various redundancy options to
keep the _system_ reliability at a reasonable level.

For disk storage, create some kind of RAID array and use similar disks
from various manufacturers. If some batch from some manufacturer shows
a higher failure rate than normal, use replacement parts from other
manufacturers.

The rapid drop in electronics cost makes it possible to use redundant
systems, unfortunately, the general drop in reliability, makes it more
or less mandatory to use redundant systems for 24x7 operations :-).
  

Hi Paul,

Paul Keinanen wrote:
> On Tue, 16 Nov 2010 16:59:42 -0700, D Yuniskis
> <not.going.to.be@seen.com> wrote:
> 
>> So, I'm in the market for some 1-2T drives,
>> SATA no doubt.  I don't need speed demons.
>> Rather, I would like something that is going
>> to be reliable, and probably run cool (this
>> makes choice of enclosure less of an issue).
> 
> If you need some degree of reliability with current consumer quality
> electronics (i.e. you are not willing to pay for military/aerospace
> components), I would suggest looking for various redundancy options to
> keep the _system_ reliability at a reasonable level.

My concerns are currently only for development use.
I.e., I keep *many* different images of the system on a drive
so I can rollback changes easily (as well as documenting
test history).  E.g., I can easily add 20G in a work session,
often considerably more.  I don't want to have to think
about what I *should* be preserving vs. what I should roll back,
etc.  The same attitude extends to not having to worry about
a premature failure (especially something that would plague
a particular "model number" of drive).

> For disk storage, create some kind of RAID array and use similar disks
> from various manufacturers. If some batch from some manufacturer shows
> a higher failure rate than normal, use replacement parts from other
> manufacturers.
> 
> The rapid drop in electronics cost makes it possible to use redundant
> systems, unfortunately, the general drop in reliability, makes it more
> or less mandatory to use redundant systems for 24x7 operations :-).

<grin>  Yes.  The problem is *predicting* which of those
manufacturers, models, etc. will be the "problems"...
(this is one reason why I opt for lots of smaller drives
on my workstations -- easier to backup and less to risk
losing on a single spindle).

On 2010-11-18, D Yuniskis <not.going.to.be@seen.com> wrote:
> Andrew Smallshaw wrote:
>> 
>> That was my first thought.  I assume we're talking about consumer
>> grade drives rather than enterprise units.  I've installed a few
>
> Not a valid assumption.  :>  I'm just looking for advice
> as to what to look *at* and what to *avoid*.  Though, when
> these projects are finished, I'll probably take them off-line
> and just use them for archival storage.

That assumption was based on the capacity you're after.  Genuine
enterprise drives simply don't go that big - the Savvios and the
like all seem to currently top out at 600GB.  I assume world+dog
is using consumer grade drives and RAID setups for bulk storage,
and keeping the pricey stuff for where there is no alternative.

> At 500G you could still be talking PATA -- though I suspect not.
> (extra credit question:  anyone know where the PATA cutoff was?)

Those are SATA-II drives.  IDE drives cerrtianly go up to 500GB -
I have a couple here that size from Maxtor and WD.  750GB are also
available from multiple manufacturers.  A little Googling found
the 1000HDGI3I-TM, a 1TB drive from Total Micro Technologies.
Can't say I've ever heard of them, but usually when I say that
about a company someone is amazed that I've somehow managed to miss
them.  My reading suggests it is the only IDE drive that size.

-- 
Andrew Smallshaw
andrews@sdf.lonestar.org

D Yuniskis wrote:


> At 500G you could still be talking PATA -- though I suspect not.
> (extra credit question:  anyone know where the PATA cutoff was?)

LBA mode initially supported for 28 bit sector numbers, 32G accordingly. 
That was further extended to 48 bits, i.e. 32KT.

Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com