From: blockedofcourse@foo.invalid   
      
   >>> The opposite is possible -- SATA drive can be plugged into SAS receptacle   
   so   
   >>> those are SAS/SATA physical connectors.   
   >>   
   >> All of my backplanes are SAS/SATA (though not mix and match).  So, I don't   
   see   
   >> the value of keeping any of the SATA (only!) sleds.  I can, of course, use   
   them   
   >> in the existing backplanes but see no advantage to keeping them over an   
   >> equal number of the SAS/SATA sleds.   
   >   
   > Yep, there is no reason unless you have SATA-only device and a box of SAS   
   > drives that you might accidentally plug in there :)   
      
   But, as I can affix SAS drives to the SAS/SATA sleds, wouldn't the sleds   
   be accepted by a SATA-only backplane?  Or, am I interpreting this from the   
   wrong point of view?   
      
   I.e., the mounting holes for SAS and SATA drives are identically placed.   
   So, I can mount a SATA or SAS drive on a SATA sled or a SAS/SATA sled.   
   (there's nothing preventing the SAS from being mounted on the SATA-only   
   sled).   
      
   So, I *could* "force" that sled into a SATA-only backplane.   
      
   I.e., the better solution would have been for the drives to have different   
   mounting hole patterns so you could NOT mount a SAS drive on a SATA-only   
   sled and have the connectors trying to mate.  As it stands currently,   
   the sleds require the person who affixes the drive to observe the   
   markings on the sled to avail himself of that protection.  (?)   
      
   > Otherwise there is absolutely no reason for SATA-only stuff.   
   >   
   >>> The actual controller that those drives are going to be connected to are   
   >>> separate question. Many SAS controllers will also work with SATA drives.   
   The   
   >>> opposite is not true.   
   >>   
   >> Yes.  The extra/augmented interface is not present on the SATA drives so   
   >> not present on a SATA-only backplane.   
   >>   
   >>> AFAIK there are no reliably working USB<->SAS docking   
   >>> stations. There are _SOME_ that claim to be SAS but those are hit and miss   
   --   
   >>> it is impossible to tell if they'll work with a particular drive.   
   SATA<->USB   
   >>> ones are aplenty, cheaper than dirt, and almost all of them work.   
   >>   
   >> I've not looked for a SAS dock as I can just pull a drive out and slap a   
   >> new/temporary drive in its place just as easily as putting one in a dock.   
   >> Especially as the backplanes tend to support higher bandwidths than the   
   >> docks.   
   >   
   > It is not all that straightforward if ALL your drives are in a hardware RAID   
   > of some kind...   
      
   I don't rely on RAID for redundancy choosing, instead, to keep multiple   
   copies of files on different spindles/machines -- and a database to help   
   me locate a replacement copy *if* a file/spindle becomes corrupted.   
   And, lets me move drives to other machines in the event of a *machine*   
   failure.   
      
   Array rebuild times are just too long for large volumes (e.g.,   
   a three-pack of 2/4/8T drives being scanned at ~150MB/s takes many   
   hours to rebuild).  And, you have no control over which part of   
   the array is being recovered -- some files are more valuable than others!   
      
   Having said that, I've a pair of machines that have drives configured   
   as single-spindle RAID0 volumes as the HBA doesn't support JBOD mode   
   (but, I have been replacing those HBAs)   
      
   >>> SAS is SCSI with serial physical interface, akin to PCIe that is PCI with   
   >>> serial physical interface. SATA is, eh, ATA with serial physical interface   
   >>> so it is totally different device.   
   >>   
   >> SAS also allows FDX communication instead of SIMPLEX and a fatter pipe.   
   >>   
   >> And, of course, tend to be more durable than SATA.   
   >   
   > SCSI are better in any respect, just more expensive and require different,   
   > more expensive controllers.   
      
   I've discarded all of my U320 drives and the machines that used them.   
   They just weren't large enough.   
      
   I still have one SCSI box (Voyager) and a FC/AL box (SB2000) but   
   those probably will be retired, soon (I use the SB2000 just to test   
   how portably I write my code as it is considerably different from   
   ARM or x86/amd64)   
      
   >> So, can you see any reason other than "inhibiting mating" for there to be   
   >> two types of sleds?  (the sleds look like swiss cheese with all the   
   >> various mounting holes supported)   
   >   
   > It is the ONLY reason behind having SATA-only sleds/connectors.   
      
   OK.  Into the tip they go.  (I'll hold onto a few of the RFI gaskets)   
   Thanks!   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)