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wkaitFlag for United States of America

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SAS Drive Connections

Im new to the SAS world and have recently purchased a Perc 5/I Raid card and two Seagate 15.5K SAS drives.  I plan on mirroring the two Seagates and using them.  The SAS drive connection is similar to the SATA drive, but slightly different.  The SATA drive has a gap between the power connector and the data connector, but in the SAS drive the gap is bridged with plastic so you cannot use a standard SAS controller to SATA cable.  Another experienced IT guru and I decided to experiment (albeit a possible slightly expensive experiment) we decided to cut the plastic piece that divides the power and the data on the SAS drive.  (We both grew up in the era of burning a hole in a DD floppy disk to create an HD floppy disk to get around the marking tactic, so we applied this same logic.)  In cutting the plastic bridge we discovered that there are in fact connectors inside the plastic bridge, which lead to contacts on the opposite side of the data and power contacts on the SAS drive connection.  Unfortunately we only saw the contacts AFTER we cut the plastic, but were able to not damage the connectors inside the cut bridge.  The contacts also appear to be soldered to the board on the SAS drive. We then made a trip to purchase the appropriate cables.  At the store we investigated an external SAS backplane.  This backplane also had the same bridged connection inside the case to accommodate the SAS drives, but to our surprise there were only standard SATA connectors on the back to connect to an SAS controller.  We found and purchased the SAS controller to SAS drive cable and investigated the cable.  We found that there were contacts within the cable housing that connects to these extra contacts on the SAS drive.  But after visual inspection it doesnt appear that the contacts span through the cable itself to the controller (we didnt cut the cable open though.)  We sed the new cable and connected the SAS drive that we hacked the plastic bridge out of and were able to mirror 2003 Server to it and boot from it just fine; everything appears to work.  So my question is if the contacts dont span through the cable to the RAID controller what the heck are the extra contacts for?  The only logical conclusions we could come up with was that this is either some sort of loopback mechanism or maybe some kind of future monitoring connection.   It doesnt seem like a marketing tactic as the cable for an SAS controller to SAS drive was $44 and is compatible with SATA (it says so on the box and we verified) but the cable for an SAS controller to SATA drive is $49 and is only compatible with SATA drives.  I have googled it with no answers yet, but will continue my search as I want to know the what and the why in such an important piece of hardware.  Any info would be greatly appreciated and I will certainly post back if I find the answer.

Thanks.
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kode99

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Hey, thanks for the response.  That's extactly what I was looking for.
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ASKER

Thanks, that was it!