On Fri, 2016-01-15 at 14:32 -0500, Anne Mulhern wrote: > > > > ----- Original Message ----- > > From: "James Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> > > To: "Anne Mulhern" <amulhern@xxxxxxxxxx> > > Cc: linux-scsi@xxxxxxxxxxxxxxx > > Sent: Wednesday, January 13, 2016 3:30:07 PM > > Subject: Re: /sys/.../enclosure_device:<something> ? > > > > On Wed, 2016-01-13 at 15:15 -0500, Anne Mulhern wrote: > > > > > > > > > > > > ----- Original Message ----- > > > > From: "James Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> > > > > To: "Anne Mulhern" <amulhern@xxxxxxxxxx>, > > > > linux-scsi@xxxxxxxxxxxxxxx > > > > Sent: Wednesday, January 13, 2016 2:15:05 PM > > > > Subject: Re: /sys/.../enclosure_device:<something> ? > > > > > > > > On Wed, 2016-01-13 at 11:28 -0500, Anne Mulhern wrote: > > > > > Hi! > > > > > > > > > > I'm looking for the most precise information available about > > > > > the > > > > > meaning of <something> > > > > > and from what it is derived. I'm also interested in what the > > > > > values > > > > > in the files in that directory > > > > > may mean. Could somebody point me there? > > > > > > > > It's in drivers/misc/enclosure.c:enclosure_link_name() > > > > > > > > > > Thanks. I will do my best with that. > > > > > > > > Also, how can there be more than one enclosure_device > > > > > subdirectory > > > > > for the same device, > > > > > or, alternatively, why isn't <something> stored in a file in > > > > > the > > > > > more > > > > > regularly named directory > > > > > /sys/.../enclosure_device? > > > > > > > > I'm not sure I parse the question, but if you're asking how can > > > > a > > > > single enclosure bay appear to have more than one device, > > > > that's > > > > when > > > > there are multiple paths to the device. > > > > > > I'm afraid the word path is so overloaded...I'm assuming that you > > > are talking about a multipathed environment, where two device > > > nodes, > > > say /dev/sdb, /dev/sdc correspond to the same disk, and are hence > > > multipathed. Of course, in that case, it makes sense that both > > > devices should share a bay. And that's what I observe. > > > > Yes, that's what I meant. > > > > > If I understand you correctly, then my question is actually the > > > opposite. Why does it look as if the directories are set up so > > > that > > > there can be multiple bays for a single device...i.e., the > > > directory > > > naming scheme allows me to specify an arbitrary number of bays > > > for > > > /dev/sdb. It seems like there should never be more than one? > > > > There is only one bay per device since a physical disk can't be in > > more > > than one bay at once. Why do you think it was set up to allow >1? > > > > Purely because the naming scheme for the directory, > 'enclosure_device:<identifier>' supports more than 1. > > This directory pops up in the directory of the parent device > representing > a block device, and should represent just the bay for that device, > AFAIU. > > The most compelling reason for this naming scheme to support more > than 1 > subdirectory is if it is necessary, i.e., there are more than one > possible. > > That might be true if my understanding of the block device's parent > device's > meaning is incorrect or if something else doesn't mean what I think > it means. The enclosure_device: is a namespace prefix. It's sysfs, so we can't have two files of the same name and <identifier> is supplied by page 7 of the enclosure device ... it could be anything. The only way to ensure we don't have a clash is to use a namespace prefix. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
