Well Solaris SAS isn''t there yet but anyway just found some interesting high density SAS/SATA enclosures. <http://xtore.com/product_list.asp?cat=JBOD> The XJ 2000 is like the x4500 in that it holds 48 drives, however with the XJ 2000 2 drives are on each carrier and you can get to them from the front. I don''t like xtore in general but the 24 bay (2.5" SAS) and 48 bay JBODs are interesting. How badly can you mess up a JBOD? -frank
>Well Solaris SAS isn''t there yet but anyway just found some interesting >high density SAS/SATA enclosures. > ><http://xtore.com/product_list.asp?cat=JBOD> > >The XJ 2000 is like the x4500 in that it holds 48 drives, however with >the XJ 2000 2 drives are on each carrier and you can get to them from >the front. > >I don''t like xtore in general but the 24 bay (2.5" SAS) and 48 bay >JBODs are interesting. How badly can you mess up a JBOD?Two words: vibration, cooling. Casper
> > How badly can you mess up a JBOD? > > Two words: vibration, cooling.Three more: power, signal quality. I''ve seen even individual drive cases with bad enough signal quality to cause bit errors. This message posted from opensolaris.org
On Fri, 26 Jan 2007, Anton B. Rang wrote:> > > How badly can you mess up a JBOD? > > > > Two words: vibration, cooling. > > Three more: power, signal quality. > > I''ve seen even individual drive cases with bad enough signal quality to cause bit errors.Yes - me too. I was a early adopter of Fibre Channel, and the first FC enclosure I had the misfortune to purchase, had really terrible signal quality and noise issues. It took me awhile to figure out if it was the beta drivers, brand new FC HBA, copper wiring, Seagate disk drives or .... The breakthrough came when I got a simple FC interface board (from Seagate[0]) that had a 3ft FC (copper) cable and could be plugged directly into a FC disk drive. At that point I knew that everything was solid, from computer system to the disk drive, and because the same drive would not perform in the FC enclosure - it was obvious where the problem lay. Looking inside the enclosure, it was wired, point-to-point, with cables and connectors that closely resemble the cable/connector you see that carries the digital audio from a CD-ROM to a PC motherboard. It was pretty obvious that the company who built this enclosure (they manufacture a bunch of disk drive enclosures - many as OEM products) did''nt realize that they were now dealing with microwave signals and needed RF (Radio Frequency) expertize in order to design a solid FC enclosure. [0] it was intended for disk drive trouble-shooting/testing etc and is still very useful if you "play" with FC disk drives. Regards, Al Hopper Logical Approach Inc, Plano, TX. al at logical-approach.com Voice: 972.379.2133 Fax: 972.379.2134 Timezone: US CDT OpenSolaris.Org Community Advisory Board (CAB) Member - Apr 2005 OpenSolaris Governing Board (OGB) Member - Feb 2006
Anton B. Rang wrote:>>> How badly can you mess up a JBOD? >> Two words: vibration, cooling. > > Three more: power, signal quality. > > I''ve seen even individual drive cases with bad enough signal quality to cause bit errors.Yep, if I crank up the amp to over 1kW, then on some frequencies, I see lots of noise on USB links as an example. You may have noticed that many vendors are now making USB cables with torroids builtin. There is still some black art involved in eliminating noise problems. However, one easy way to do it is well proven in the PCB design space. We leverage that with Thumper which has no internal disk cables. In fact, you should notice that many Sun designs have few, if any, internal cables. Cables are a source of reliability issues, so they are best when they don''t exist. [waxing nostalgic] When the designers were planning the Shinkansen (Japanese high speed train system) they had 150 years of train accident data to study. Not surprisingly, most train accidents occured at crossings. To help avoid accidents, they eliminated crossings. Good design is a good thing. -- richard