Following up on some of this forum's discussions, I read the manuals on SuperMicro's SC847E26-RJBOD1 this weekend.
At the very least, this box provides dual-expander backplanes (2 BPs for a total of 45 hot-swap disks), so each JBOD has 4 outgoing SFF8087 (4xSATA iPass) connectors. However it seems that the backplane chips are doubled for multipathing-failover within a single head node with dual connections from same or different HBAs. (Further on, backplanes may be daisy-chained to attach other JBODs to the same HBA path - but if you don't care much for bandwidth limitations). According to the docs, each chip addresses all disks on its backplane, and it seems implied (but not expressly stated) that either one chip and path works, or another. So if your application can live with the unit of failover being a bunch of 21 or 24 disks - that might be a way to go. However each head would only have one connection to each backplane, and I'm not sure if you can STONITH the non-leading head to enforce failovers (and enable the specific PRI/SEC chip of the backplane). Also one point was stressed many times in the docs: these failover backplanes require use of SAS drives, no SATA (while the single-path BPs are okay with both SAS and SATA). Still, according to the forums, SATA disks on shared backplanes often give too much headache and may give too little performance in comparison... I am not sure if this requirement also implies dual SAS data connectors - pictures of HCL HDDs all have one connector... Still, I gess my post poses mre questions than answers, but maybe some other list readers can reply... Hint: Nexenta people seem to be good OEM friends with Supermicro, so they might know ;) HTH, //Jim Klimov _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
