Drives of same model in RAID 1/10 ?

Drives of same model in RAID 1/10 ?

[Mark Hellman]

I am in the process of deciding which SATA-II drives should I choose for an
external RAID system. I heard that it was safer to choose drives from
different manufacturers to reduce the chance of near-simultaneous failure
due to model-specific issues.
Is this so?
And are there other potential problems related with choosing drives from
different manufacturers?


Mark

Re: Drives of same model in RAID 1/10 ?

[Andy Smith]

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On Mon, Jul 24, 2006 at 07:46:21PM +0100, Mark Hellman wrote:
> I am in the process of deciding which SATA-II drives should I choose for an
> external RAID system. I heard that it was safer to choose drives from
> different manufacturers to reduce the chance of near-simultaneous failure
> due to model-specific issues.
> Is this so?

It's certainly safer.. whether you think it is worth the trouble is
your call.

> And are there other potential problems related with choosing drives from
> different manufacturers?

The only issue is the obvious one that the manufacturers are usually
fairly vague about the exact usable size of each disk.  If you
bought half the disks from one manufacturer and half from another
then you should be able to pair them up and use the minimum of the
size of each pair.

Cheers,
Andy

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Re: Drives of same model in RAID 1/10 ?

[Jeff Breidenbach]

> The only issue is the obvious one that the manufacturers are usually
> fairly vague about the exact usable size of each disk.  If you
> bought half the disks from one manufacturer and half from another
> then you should be able to pair them up and use the minimum of the
> size of each pair.

In a similar vein, if the drives have different speeds and you may be
wasting some performance. The faster drives may be forced to
sit around waiting for an I/O operation to complete on the slowpoke.

Jeff

Re: Drives of same model in RAID 1/10 ?

[hahn]

>> I am in the process of deciding which SATA-II drives should I choose for an
>> external RAID system. I heard that it was safer to choose drives from
>> different manufacturers to reduce the chance of near-simultaneous failure
>> due to model-specific issues.
>> Is this so?
>
> It's certainly safer.. whether you think it is worth the trouble is
> your call.

it would be great to know the numbers.  I WAG that this pretty 
theoretical model-specific failure mode is insignificant compared 
to environment or wear/load-specific ones.  I can imagine the former
was more of a concern in the days of disks on shared buses (SCSI, FC, 
even IDE), when a model-specific response to some protocol oddity
might cause group failures.

nowadays, a SATA disk will probably share power, air, vibration with 
its peers, and in some sense, IO load.  but I suspect there's enough
variance in the latter to make synchronized dying uncommon.  at least 
short-scale synchrony.  vendor would be much less relevant to 
power/air/vibration issues.

Re: Drives of same model in RAID 1/10 ?

[Justin Piszcz]

On Mon, 24 Jul 2006, Andy Smith wrote:

> On Mon, Jul 24, 2006 at 07:46:21PM +0100, Mark Hellman wrote:
>> I am in the process of deciding which SATA-II drives should I choose for an
>> external RAID system. I heard that it was safer to choose drives from
>> different manufacturers to reduce the chance of near-simultaneous failure
>> due to model-specific issues.
>> Is this so?
>
> It's certainly safer.. whether you think it is worth the trouble is
> your call.
>
>> And are there other potential problems related with choosing drives from
>> different manufacturers?
>
> The only issue is the obvious one that the manufacturers are usually
> fairly vague about the exact usable size of each disk.  If you
> bought half the disks from one manufacturer and half from another
> then you should be able to pair them up and use the minimum of the
> size of each pair.
>
> Cheers,
> Andy
>

So far the WD 400GB -KD drives and Seagate 400GB seem to have the same 
amount of sectors.