PowerEdge HDD/SCSI/RAID

Last reply by 08-09-2012 Unsolved
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2 Bronze
2 Bronze
121284

confused. PERC5+SATA, no interposer

We've just received a PowerEdge 2950 with PERC 5/i controller. We've ordered a single SATA drive since we'd like to put in 6 of our own.

My understanding is that SATA drives must be connected to PERC 5 backplane with an interposer board (part #PN939). This was also confirmed by a DELL tech on the phone.

What I am confused about is that DELL's SATA came installed without an interposer board. Looking into the drive bays, I can see markings such as "J_SASDRV0" and so on through 5. I've replaced DELL's drive with my own SATA drive and it was recognized and seems to function fine without the interposer. So is the interposer board needed at all then? I need to order additional HDD trays and now I am not sure if I have to order interposer boards for each drive. Maybe I am not getting it right and any advice is appreciated. Thanks!
Replies (15)
2 Bronze
2 Bronze
361

yes... that's true. Thank you so much!

4 Beryllium
361

Also, SAS drives are dual ported, sata are single port. The interposer allows a sata disk to be used in an external array with two contollers

2 Bronze
2 Bronze
361

"external array with two contollers" what do you mean with this? my english is not that good :) do you mean the powervault md1000 ?

7 Gold
361

"external array with two contollers" what do you mean with this? my english is not that good :) do you mean the powervault md1000 ?

That is correct; either a PERC6E with dual connections to an MD1000, an MD1000 connected to an MD3000/i or for when you put the drive directly into an MD3000/i (or MD3200/3600).

Member since 2003

4 Beryllium
361

Yes like that. MD3000 and greater. MD1000 and greater. EMC Storage etc. These systems have 2 contollers for redundancy and also other things like load balancing. A SAS disk can connect to both controllers but only 1 is active. If a contoller fails the disk will use the other connection(port) to continue working. A SATA disk is single port so can only physically connect to one controller. If that controller fails then the disk will go offline. The Interposer contains logic(chips) that turn the single port into dual port so it will function like a SAS disk. The interposer does other stuff as well not sure what though. On EMC arrays it fools the bus into thinking the disk has a 4gb interface not 3gb.

2 Bronze
2 Bronze
361

Very good answer. I called dell support to explain the purpose of interposers and the guy from dell just kept aaaa aaaa well... well... :)) no clean answer...

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