Hi Peter Before going into details, overall what you are doing is emulating SCSI disks for access by initiators on the SAN. So for "each disk", one should be able to say things like:
- Which initiators can access it. - Through which targets can the initiators access it. - What is the SCSI LUN number a given initiator sees when they access this disk. These setting are known as "lun mappings". Also you should be able to specify the storage where the data for this emulated disk is stored. This can be a zvol, a file etc. This is known as "backing store". Also even though you are specifying the LUN mappings for each lun, COMSTAR does not also you to specify initiators and targets individually. You have to specify a list of initiators and targets known as "host groups" and "target groups" (even if the list has only one member). So to put everything together: A LU is an actual emulated SCSI device (mostly a disk, but you can also emulate other SCSI devices like tape etc.). If the LU is a disk, then it needs a backing store which is mostly specified as a zvol (also known as volume). A target is simply an access point for an initiator to come in. When an initiator logs into a target, it sees a bunch of LUs depending upon the LUN mappings you specify. A view is simply another name for a single LUN mapping entry. Target portal group is an iSCSI construct. It is basically a way to tie in a bunch of IP addresses with an iSCSI target. I think it is described in COMSTAR Admin guide. But it is different from "target group" which is basically a list or targets which is then used inside LUN mappings. Sumit > -----Original Message----- > From: storage-discuss-boun...@opensolaris.org [mailto:storage-discuss- > boun...@opensolaris.org] On Behalf Of Peter Taps > Sent: Monday, November 08, 2010 4:08 PM > To: storage-discuss@opensolaris.org > Subject: [storage-discuss] Relationship between volume, LU, target, > target group, etc. > > Folks, > > I have gone through various articles on setting up iSCSI initiator and > have successfully managed to share an iSCSI volume following the steps. > This was a simple test scenario. Now, I am trying to set up a specific > scenario but I am confused on proper relationship between various terms > that are used. I would appreciate your help in making me understand the > relationship between the following terms: > > - Volume > - LU > - Target > - Target Group > - Target Portal Group > - Host Group > - View > > As I understand: > 1. There is a one-to-one relationship between a volume and its LU. > 2. A target group consists of targets and a host group consists of > hosts. > 2. A view consists of one host group, one target group, and one or more > LUs. > > What I don't understand: > 1. At first, I thought there is a one-to-one relationship between an LU > and a target. However, this doesn't seem to be the case. Why would you > need more than one target in a target group? > 2. Where does the target portal group fit in? > > In my scenario, I would like to share volumes v1 and v2 with hosts h1 > and h2. I would also like to limit the network to go through ip > addresses p1 and p2 only. Can someone please give me just the broad > steps;'' > > Thank you in advance for your help. > > Regards, > Peter > -- > This message posted from opensolaris.org > _______________________________________________ > storage-discuss mailing list > storage-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/storage-discuss _______________________________________________ storage-discuss mailing list storage-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/storage-discuss
