HiSoC8Y Posted May 31, 2012 Share Posted May 31, 2012 Hi As many of you guys use SATA cards with PCI-E 2.0, I was wondering how can you achieve the 6 Gbps for each disk (SATA III drive), with all 8 drives that are connected via the PCI-E? Can someone explain this part please? Thanks Quote Link to comment
brian89gp Posted May 31, 2012 Share Posted May 31, 2012 PCIe 1.0 per channel = 250MB/s = 2Gb/s PCIe 2.0 per channel = 500MB/s = 4Gb/s PCIe 3.0 per channel = 1Gb/s = 8Gb/s First, it is highly unlikely that all 8 disks are going to push the maximum bus speed at the same time. It is also unlikely that a single SATA drive would even push the maximum bus speed for SATA 3. (unless you are talking about high end SSD SATA drives). For your theoretical question though, 8 disks at 6Gb/s each = 48Gb/s. It would be possible with a 16x PCIe 2.0 card or 8x PCIe 3.0 card. With the common adoption of 10Gb ethernet, 16Gb fibre channel, and QDR Infiniband in the server market the PCIe 3.0 bus is becomming pretty common. PCIe 2.0 isn't fast enough anymore. Quote Link to comment
c3 Posted May 31, 2012 Share Posted May 31, 2012 The spinning drives don't go 6Gbps. A fast spinning drive delivers 140MB/s to 204MB/s, well under 2Gbps. So from there you build caching and switching to allow multiple devices to leverage the bandwidth of the SAS interface and/or the card slot. Raptor testing on 3G vs 6G http://www.bit-tech.net/hardware/storage/2010/08/23/western-digital-velociraptor-600gb-review/3 1MB/s difference. Quote Link to comment
HiSoC8Y Posted May 31, 2012 Author Share Posted May 31, 2012 Thank you guys, well explained! Any idea of SATA controllers, with the max number of ports? I'm planning to use either 3TB 6Gbps or 4 TB 6Gbps, with max. # of drives possible so far, probably 20 or 22 drives. Thanks!!! Quote Link to comment
brian89gp Posted May 31, 2012 Share Posted May 31, 2012 If you have a little extra money, use SAS card(s). Quote Link to comment
HiSoC8Y Posted June 1, 2012 Author Share Posted June 1, 2012 If you have a little extra money, use SAS card(s). Why SAS card? Quote Link to comment
brian89gp Posted June 4, 2012 Share Posted June 4, 2012 If you have a little extra money, use SAS card(s). Why SAS card? For enterprise features and reliability. Think Realtec vs Intel for a network card, if you had the choice which would you choose? With the abundance of IBM M1015 cards they are within the price range of a lot of home users now. -SAS expanders -true hot swap -almost all use SFF-8087 connectors which make it a lot easier in cable management -support in ESXi if you ever go that route -able to use SAS drives if it tickles your fancy -more consistent driver quality Just double check your motherboard before you buy. A lot of consumer desktop boards don't like mass storage controllers being plugged into them, especially to their higher bandwidth video card slots. Quote Link to comment
HiSoC8Y Posted June 5, 2012 Author Share Posted June 5, 2012 If you have a little extra money, use SAS card(s). Why SAS card? For enterprise features and reliability. Think Realtec vs Intel for a network card, if you had the choice which would you choose? With the abundance of IBM M1015 cards they are within the price range of a lot of home users now. -SAS expanders -true hot swap -almost all use SFF-8087 connectors which make it a lot easier in cable management -support in ESXi if you ever go that route -able to use SAS drives if it tickles your fancy -more consistent driver quality Just double check your motherboard before you buy. A lot of consumer desktop boards don't like mass storage controllers being plugged into them, especially to their higher bandwidth video card slots. Hi Brian, kind of confused now i'm planning to goo h te Norco 4224 case. Correct me if Im wrong, with that case, the end part of the drive bays is SAS (the SFF-8087), right? that means I basically need a SAS card (is it called SAS expanders also?), which you mentioned? Quote Link to comment
BobPhoenix Posted June 5, 2012 Share Posted June 5, 2012 SAS expanders are like Port Multipliers for SATA. You connect a SAS controller (like IBM M1015) to the SAS expander which then multiplies the number of drives you can connect to the controller. I currenly have my M1015 connected to an Intel RES2SV240 SAS expander so that I can connect > 8 drives to my single M1015. Quote Link to comment
brian89gp Posted June 5, 2012 Share Posted June 5, 2012 SAS expanders are like Port Multipliers for SATA. You connect a SAS controller (like IBM M1015) to the SAS expander which then multiplies the number of drives you can connect to the controller. I currenly have my M1015 connected to an Intel RES2SV240 SAS expander so that I can connect > 8 drives to my single M1015. Yup. If you want 24 drives you would need either 3x 8-port cards or 1x 8-port card and a SAS expander. Both methods work fine, depending on how many PCIe slots your motherboard has. Also provides an interesting benefit if using ESXi. My motherboard has 7x PCIe slots and one onboard SAS2008 controller, using SAS expanders I could have 8x unRAID servers with 22+ drives each, all running off the same motherboard. That wouldn't be possible without SAS expanders and had to use up 3 slots per unRAID server.... (not that I would have that many anyway, but it provides options) Quote Link to comment
HiSoC8Y Posted July 4, 2012 Author Share Posted July 4, 2012 Any recommendation on a PCIe 3.0 cards? I'm planning to run a system with 20 HDD. Quote Link to comment
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