On Fri, Jul 25, 2014 at 10:30 PM, Christian Balzer <chibi at gol.com> wrote: > > If you read the section E of the manual closely and stare at the back of > the case you will see that while there are indeed 4 external SAS > connectors right next to the power supply, only 2 of those are inbound > (upstream, HBA) and the other 2 outbound, downstream ones. > > So my number stands, 4 lanes at 6Gb/s times 2 = 48Gb/s. > > Which also means that if one were to put faster drives in there, the > backside with slightly more bandwidth would be the preferred location. > I have many of these in production. There are multiple ways you can cable them. If you do not cascade them which will further divide your throughput you can use all 16 SAS lanes exposed through the back of the chassis. 8 to the front back plan 8 to the rear for a total of 96Gb/s. This puts 24 drives on 8 SAS lanes and 21 drives on the remaining 8. If you want to cascade to another chassis, you will have to supply your own internal cables to cascade the two back planes. For DR disk pools I cascade them. For production systems I only direct connect the SAS expanders to the HBAs. -Chip -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20140726/3d7515eb/attachment.htm>
 |