Hi there,
let's for example take the BPN-SAS2-826EL2. It has two dual-port expanders with 2 ports each:
(also see: http://www.supermicro.com/manuals/other/BPN-SAS2-826EL_1.0.pdf or http://www.supermicro.com/manuals/chassis/2U/SC826.pdf Appendix F)
PRI_J0
PRI_J1
SEC_J0
SEC_J1
Given supermicro's definition J0's are "From HBA or higher backplane" and J1's are "To lower backplane in cascaded system".
Now my question is: how to implement a simple n-way cascaded multipath setup (consisting of e.g. 2 servers with 2 SAS HBAs each and 2 JBODs each with that backplane mentioned above)?
I can only imagine implementing this, if I can plug a HBA to J1's in the end of the multipath loop, since the J0's are used for cascading at least for the (n-1) last JBODs in the loop.
The goal basically is to have two server's seeing ALL disks in the whole SAS domain (I'd solve the rest within software). Basically I could use a SAS switch, but do I really have to?
A hopefully simple example of what I am trying to achieve:
Server1-HBA1 => JBOD1-PRI_J0
Server1-HBA2 => JBOD1-SEC_J0
JBOD1->PRI_J1 => JBOD2->PRI_J0
JBOD1->SEC_J1 => JBOD2->SEC_J0
JBOD2->PRI_J1 => Server2-HBA1
JBOD2->SEC_J1 => Server2-HBA2
Is this possible? If not - why not (I'd love to hear some technical detail) and if yes - is there any other/better way (bear in mind, that the 2 JBODs are just an example, it could also be easily 4 or more - therefor using a "star connection scheme" is not feasible).
Are there any other caveats/pitfalls I should be aware of?
regards,
po
let's for example take the BPN-SAS2-826EL2. It has two dual-port expanders with 2 ports each:
(also see: http://www.supermicro.com/manuals/other/BPN-SAS2-826EL_1.0.pdf or http://www.supermicro.com/manuals/chassis/2U/SC826.pdf Appendix F)
PRI_J0
PRI_J1
SEC_J0
SEC_J1
Given supermicro's definition J0's are "From HBA or higher backplane" and J1's are "To lower backplane in cascaded system".
Now my question is: how to implement a simple n-way cascaded multipath setup (consisting of e.g. 2 servers with 2 SAS HBAs each and 2 JBODs each with that backplane mentioned above)?
I can only imagine implementing this, if I can plug a HBA to J1's in the end of the multipath loop, since the J0's are used for cascading at least for the (n-1) last JBODs in the loop.
The goal basically is to have two server's seeing ALL disks in the whole SAS domain (I'd solve the rest within software). Basically I could use a SAS switch, but do I really have to?
A hopefully simple example of what I am trying to achieve:
Server1-HBA1 => JBOD1-PRI_J0
Server1-HBA2 => JBOD1-SEC_J0
JBOD1->PRI_J1 => JBOD2->PRI_J0
JBOD1->SEC_J1 => JBOD2->SEC_J0
JBOD2->PRI_J1 => Server2-HBA1
JBOD2->SEC_J1 => Server2-HBA2
Is this possible? If not - why not (I'd love to hear some technical detail) and if yes - is there any other/better way (bear in mind, that the 2 JBODs are just an example, it could also be easily 4 or more - therefor using a "star connection scheme" is not feasible).
Are there any other caveats/pitfalls I should be aware of?
regards,
po
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