On May 30, 2011, at 2:37 AM, Jim Klimov wrote: > Following up on some of this forum's discussions, I read the manuals on > SuperMicro's > SC847E26-RJBOD1 this weekend.
We see quite a few of these in the NexentaStor installed base. The other commonly found 3.5" 24-drive JBOD is the DataON DNS-1600, a product staggeringly similar to Sun's J4400. > 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). We also commonly see the dual-expander backplanes. > 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. For SAS targets, both paths work simultaneously. > 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). The NexentaStor HA-Cluster plugin manages STONITH and reservations. I do not believe programming expanders or switches for clustering is the best approach. It is better to let the higher layers manage this. > 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... The cost of a SATA disk + SATA/SAS interposer is about the same as a native SAS drive. Native SAS makes a better solution. > I am not sure if this requirement also implies dual SAS data connectors - > pictures > of HCL HDDs all have one connector... These are dual ported. > 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 ;) Yes :-) -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
