On Mon, May 30, 2011 at 1:35 PM, Jim Klimov <j...@cos.ru> wrote: > Thanks, now I have someone to interrogate, who seems to have > seen these boxes live - if you don't mind ;) > > ----- Original Message ----- > From: Richard Elling <richard.ell...@gmail.com> > Date: Monday, May 30, 2011 22:04 > > > 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. > > Does this mean that if the J0 uplinks of backplanes are connected > to HBAs in two different servers, both of these servers can address > individual disks (and the unit of failover is not a backplane but a disk > after all)? > > And if both HBAs are in a single server, this doubles the SAS link > throughput by having two paths - and can ZFS somehow balance > among them? > > > > > > 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. > Makes sense. > > Since I originally thought that only one path works at a given time, > it may be needed to somehow shutdown the competitor HBA/link ;) > > > > 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. > Does this mean mecanically two 7-pin SATA data ports and a wide > power port, for a total of 3 connectors on the back of HDD, as well > as on the backplane sockets? Or does it mean something else? > > Because I've looked up half a dozen of SuperMicro-supported drives > (bold SAS in the list for E2-series chassis), and in the online shops' > images they all have the standard 2 connectors (wide and 7-pin): > http://www.supermicro.com.tr/SAS-1-CompList.pdf > The HCL is rather small, and "other components may work but are > not supported by SuperMicro". > > And to be more specific, do you know if Hitachi 7K3000 series SAS > models HUS723020ALS640 (2Tb) or HUS723030ALS640 (3Tb) > are suitable for these boxes? > > Does it make sense to keep the OS/swap on faster smaller drives like > a mirror of HUS156030VLS600 (300Gb SAS 15kRPM) - or is it > a waste of money? (And are they known to work in these boxes?) > > > > Hint: Nexenta people seem to be good OEM friends with > > Supermicro, so they > > > might know ;) > > > > Yes :-) > > -- richard > > Thanks! > > //Jim Klimov > > SAS drives are SAS drives, they aren't like SCSI. There aren't 20 different versions with different pinouts.
Multipathing is handled by mpxio. --Tim
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