Mixing SAS and SATA drives - working (with correct hyperlinks)
Radim Hejc
hejc at u-turnmediagroup.com
Tue Mar 4 18:09:17 CST 2008
Hello Jeremy,
Thanks for the info!
But then i don't understand one thing:
Why i'm experincing problems runing SAS together with original SATA
caddy *with* interposer
and when running SAS togehter with SATA without interposer everything
works just fine?
it has to have opposite result ??
R.H.
Radim Hejč
IT infrastructure
U-TURN, a.s.
Argentinská 38/286
17000 Praha 7, Czech rep.
Jeremy Cole napsal(a):
> Hi Radim,
>
> That card you're looking at is called an "interposer" and makes the
> SATA drive pretend to be a SAS drive in order to allow it to support
> more advanced features that SAS supports, and to run in SAS
> environments. The interposer card provides the following features:
>
> * Dual Port -- SAS drives have the ability to be connected in an
> active-active manner to two controllers simultaneously. This is what
> the extra pins on the interposer card are for.
>
> * Boost Signal Voltage -- SATA drives run at a lower signal voltage
> than SAS, so the interposer card boosts the signal voltage to SAS levels.
>
> * Command Set -- The interposer card understands the full SAS command
> set and drives the SATA drive using the more limited SATA command set.
>
> * WWN -- SATA drives are identified on the bus by the port they are
> connected to. SAS drives are uniquely identified by a WWN (World Wide
> Name) which doesn't change when they are moved from slot to slot.
>
> There are a few caveats with the SAS vs. SATA and mixing them:
>
> * If you want to run SATA drives in an external enclosure such as the
> MD1000, you should normally have interposer cards on the drives.
>
> * If you mix SATA (without interposer) with SAS on the same
> controller, all drives will run at the lower SATA signal voltage
> instead of the SAS voltage, and you may experience strange behaviour.
>
> It might not be a bad idea to read up here:
>
> http://en.wikipedia.org/wiki/Serial_Attached_SCSI#SAS_vs_SATA
>
> Regards,
>
> Jeremy
>
> Radim Hejc wrote:
>> Sorry, there was wrong hyperlinks for all pictures, all pointing to
>> one wrong picture, so here is correct letter again :)
>>
>> -----------------------
>>
>> After some experiments i found following
>> original caddies with sata drives from Dell looks like this
>> http://www.mixx.org/dell/sata_red.jpg
>>
>> IMHO that whole reduction is there to add these pins
>> http://www.mixx.org/dell/sata_pins.jpg
>> these pins are always on SAS drives connectors, but these are regular
>> on SATA connectors, dell reduction add them also for SATA drives,
>> does enyone know what are these for? is just for hotswap?
>>
>> (i found some info on SUN
>> http://docs.sun.com/source/820-0046-10/appc-pinouts.html it seems
>> that these pins
>> have just Ground and no signal)
>>
>>
>> Weird thing is - when you connect to backplane SAS drives togehter
>> with original caddies from dell (SATAu)with reduction
>> PERC6/i has problems as i described before
>>
>> As i have spare caddies without reduction (SATA) which i bought on
>> Ebay for $15 for piece i conenct two Seagate 750GB spare drives
>> to them and found this interresting thing
>>
>> When you connect caddies with SAS together with caddies with SATA
>> drive without this Dell reductions
>> as here http://www.mixx.org/dell/sata_no_red.jpg everything works
>> without any problem :)
>>
>> Does anyone has an explanation?
>>
>> Drives was connected as twice RAID1 - one for SAS and one for SATA
>> drives, tried on PE 2950 with PERC6/i controller
>>
>>
>> R.H.
>>
>> Radim Hejč
>> IT infrastructure
>> U-TURN, a.s.
>> Argentinská 38/286
>> 17000 Praha 7, Czech rep.
>>
>>
>>
>>
>> Tony Molloy wrote:
>>> On Tuesday 04 March 2008 16:35:33 Radim Hejc wrote:
>>>
>>>> I was trying today to mix two 76GB SAS 15krpm Fujitsu drives and two
>>>> 750GB Seagate SATA drives together
>>>> (2x RAID1 both Dell Originals) on PE 2950, but after server reboot i'm
>>>> still getting messages about Foreign configuration
>>>> from PERC/6i controller, then one of SATA drives is always degraded.
>>>> When i removed SAS everything seems to work fine
>>>>
>>>> strange thing, i will research more
>>>>
>>>>
>>>
>>> That's interesting. That suggests that you can't mix them on the
>>> same controller even if they are separate RAID arrays. I'll be
>>> interested to hear what you come up with.
>>>
>>> In the end I could always go with all SATA drives. It would be
>>> cheaper ;-)
>>>
>>> Tony
>>>
>>>
>>>> Radim Hejc(
>>>> IT infrastructure
>>>> U-TURN, a.s.
>>>> Argentinská 38/286
>>>> 17000 Praha 7, Czech rep.
>>>>
>>>> Tel.: +420.777190160
>>>> ICQ: 11064792
>>>>
>>>> Tony Molloy napsal(a):
>>>>
>>>>> On Tuesday 04 March 2008 11:11:56 Mark Watts wrote:
>>>>>
>>>>>> On Tuesday 04 March 2008 10:51:12 Tony Molloy wrote:
>>>>>>
>>>>>>> On Tuesday 04 March 2008 09:49:37 Hostmaster wrote:
>>>>>>>
>>>>>>>>>>> Can't mix SATA and SAS disks. So we can't supply 2X73GB, SAS,
>>>>>>>>>>> 3.5-inch, 15.000 rpm Hard Drive 4X750GB, SATA, 3.5-inch,
>>>>>>>>>>> 7200 rpm
>>>>>>>>>>> Hard Drive. Instead I've configured 2X73GB, SAS, 3.5-inch,
>>>>>>>>>>> 15.000
>>>>>>>>>>> rpm Hard Drive 4X400GB, SAS, 3.5-inch, 10,000 rpm Hard Drive.
>>>>>>>>>>>
>>>>>>>>> Can I do this and if I can how do I get Dell to supply me with
>>>>>>>>> that
>>>>>>>>> configuration.
>>>>>>>>>
>>>>>>>> AFAIK its *technically* possible to mix them, however it isn't
>>>>>>>> a Dell
>>>>>>>> supported configuration, therefore they won't sell them that way.
>>>>>>>> Several of the guys from Enterprise Storage frequent these
>>>>>>>> lists, so
>>>>>>>> they will be able to give you the final word, but it might just be
>>>>>>>> easier to buy the server with the supported config (ie just the
>>>>>>>> two
>>>>>>>> SAS drives for the OS), and then put a separate order for the four
>>>>>>>> SATA drives, but check with someone who knows the PERC6/i
>>>>>>>> better than
>>>>>>>> me before buying!
>>>>>>>>
>>>>>> This question has been asked before.
>>>>>>
>>>>> As I said in my mail I know it has been asked before but I'm just
>>>>> about
>>>>> to spend 50,000+ euros on a rack so I wanted to be sure.
>>>>>
>>>>>
>>>>>> You can mix SATA/SAS disks on the same backplane, but the cannot
>>>>>> be in
>>>>>> the same logical volume.
>>>>>>
>>>>> That was my impression of the previous thread so my RAID1/RAID5
>>>>> configuration should work. The problem then is to get Dell to sell
>>>>> that
>>>>> configuration to me.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Tony
>>>>>
>>>>>
>>>>>> http://lists.us.dell.com/pipermail/linux-poweredge/2008-February/035159.
>>>>>>
>>>>>> htm l
>>>>>>
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