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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!
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!
evilbug
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May 4th, 2007 18:00
Message Edited by evilbug on 05-04-2007 02:59 PM
evilbug
3 Posts
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May 4th, 2007 23:00
The HDD caddy that DELL told me (and probably others) to buy for SATA drives is part number CC852. This tray, I was finally told, is longer (I guess different hole placement?), so it requires the interposer board to simply extend the HDD so it'd reach the backplane. Interposer board doesn't have any advantage or disadvantage over connecting SATA drive directly to the backplane.
The caddy part number that I purchased is F9541. It does not require the interposer board and lets a SATA drive connect directly to the backplane.
cjtompsett
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May 8th, 2007 16:00
tommo666
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May 10th, 2007 20:00
tbleier
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May 21st, 2007 16:00
I have a PowerEdge 2900 which I suppose uses the same backplane as the 2950. I ordered it with 2 SATA drives (250GB). The are in a a caddy that is marked with "SATA + SAS" and they have the "interposer" board.
Then I ordered a 80 GB SATA drive, since it seems the cheapest way to get the caddy here (EUR 45,- for drive + caddy). It came only with the harddisk (no interposer), and was marked with "SATA" only. The screw holes were obviously at different positions, so that the bare drive still connects to the backplane.
Both solutions work, so I see no difference.
Just my 2c,
__
/homas
BTW: where can one get that caddies - cheaper than EUR 45,- (around $60) - in Europe?
Message Edited by tbleier on 05-21-2007 12:42 PM
theflash1932
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August 9th, 2012 11:00
Not only do SAS drive typically have a higher RPM (10K/15K vs typical SATA 7.2K), but SAS has many other features that make them faster than SATA (full duplex, caching, performance settings, etc.):
www.intel.com/.../CS-031831.htm
blog.whitesites.com/SAS-RAID-0-VS-SCSI-RAID-0-VS-SATA-Benchmarks__633689244191943184_blog.htm
ftp://ftp.compaq.com/pub/products/servers/proliantstorage/drives-enclosures/sata-vs-sas.pdf
alex_sabau
5 Posts
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August 9th, 2012 11:00
hello, the topic is very old, but i hope someone still reads it. I was also very confused with this whole sata sas interposer thing. First i read on some forum that interposer can make sata look like sas to the system, therefore allowing SAS + SATA in RAID1 on the same virtual drive. WRONG!!! there is no way that could ever work. Then i read that the interposers are mandatory for the SATA drives to work on perc5i controler. WRONG again!!! SATA drives work with 2 different caddys without any interposer. So... interposers are no use for poweredge 2900 - 2950 what so ever! they are a waste of time. the only thing is... SATA are like 20x times slower then SAS drives.
Config: dell poweredge 2950 6 hdd bays
hdds: 2 seagate 1TB sas 7200k rpm vs. 2 seagate 1TB sata 7200k rpms
after setting them up in raid config utility at boot, the 4 hdds began mirroring.
SAS drives - 24% done
SATA - 4% done
Am i doing something wrong? or the sata drives are that slow... ?
alex_sabau
5 Posts
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August 9th, 2012 13:00
thank you for your quick reply. but in my case the rpm are the same, so that leaves the other feathures that the sas has extra. how reliable are SATA on a hosting server ? talking about speed and functionality... ??
alex_sabau
5 Posts
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August 9th, 2012 13:00
"external array with two contollers" what do you mean with this? my english is not that good :) do you mean the powervault md1000 ?
alex_sabau
5 Posts
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August 9th, 2012 13:00
yes... that's true. Thank you so much!
tommo666
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August 9th, 2012 13:00
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
theflash1932
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August 9th, 2012 13:00
If you look at the matrix on the Intel doc, many of the features affect reliability too ... error recovery and other SAS settings that SATA drives do not have. Another thing that addresses reliability is Dell's warranty ... SATA drives, unless you purchase an extended warranty to cover SATA, is only 1 year, where the SAS drives are covered for the term of the server's warranty, up to 5 years.
alex_sabau
5 Posts
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August 9th, 2012 14:00
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...
Dev Mgr
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August 9th, 2012 14:00
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).
tommo666
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August 9th, 2012 14:00
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.