[Discuss] SAS drives

[feenberg at nber.org (Daniel Feenberg)]

On Wed, 3 Aug 2011, Dan Ritter wrote:

> On Wed, Aug 03, 2011 at 11:09:09AM -0400, Daniel Feenberg wrote:
>>
>>
>> On Wed, 3 Aug 2011, Dan Ritter wrote:
>>
>>> On Wed, Aug 03, 2011 at 10:05:55AM -0400, Edward Ned Harvey wrote:
>>>>> From: discuss-bounces+blu=nedharvey.com at blu.org [mailto:discuss-
>>>>> bounces+blu=nedharvey.com at blu.org] On Behalf Of Dan Ritter
>>>>>
>>>>> This is bizarre. SATA and SAS use the same cabling,
>>>>
>>>> Sometimes true, sometimes not.
>>>> I have a Sun server X4275 which has a mixture of SATA and SAS drives in it.
>>>> No problem.
>>>> Later I bought an Oracle server X4270 (yes, the later model has a lower
>>>> number, go figure.)  It has only SAS drives, and the connector is different.
>>>
>>> Can you describe the connector? And is it on the drives, or on a
>>> backplane?
>>
>> In my case the socket on the drive has a bit of plastic that
>> prevents an ordinary SATA cable from plugging in. The drives are
>> Seagates. It does look to me like a cable connector could be
>> constructed that would work in both types of drives, but none of the
>> various SATA cables I have are so constructed.
>
> Oh, OK. Yes, SAS controllers can talk to SAS or SATA drives, but
> SAS drives have a block so that only SAS controllers can talk to
> them.

How effective is this block? It makes you get a special SAS cable to plug 
into the drive, but doesn't the controller end of the special cable plug 
into either a SAS or SATA controller? After all, the SAS controller port 
has to accept either cable, because it always supports both types of 
drives.

Dan Feenberg

>
> Sorry for the confusion.
>
> -dsr-
>