#473 iSCSI target definition should allow just 1 extent or device

v0.69x
closed
Volker
WebGUI (143)
5
2012-10-28
2008-12-20
eyore
No

At present (0.69RC2 Kralizec (revision 4083)) the webGUI allows an iSCSI target definition to include multiple extents (and, I believe, multiple devices). AFAIK it should allow a target to be defined as EXACTLY ONE extent or device.

Discussion

  • Volker

    Volker - 2008-12-21

    Hi,
    this is wrong. It is allowed to define a target containing multiple devices or extents.

    See below (taken from the netbsd-iscsi FAQ):

    Q3. So how do I use it?

    A3. Firstly, you need to set up the iSCSI target. The target is
    simply sitting there, waiting for requests for blocks. So we need to
    configure the target with an area of storage for it to present to the
    initiators.

    To set up the target, you need to edit the /etc/iscsi/targets file.
    It has a certain layout, to provide a means of (a) mirroring and (b)
    combining multiple areas to present one large contiguous area of
    storage. This can be multiply-layered.

    The basic unit of storage is an extent. This can be either a file
    or a device. The offset of the start of the extent to be presented
    must be given, and also the length of the extent.

    A device is made up of one or more extents, and/or one or more
    other devices.

    At the highest level, a target is what is presented to the initiator,
    and is made up of one or more devices, and/or one or more extents. <---------

    Regards
    Volker

     
  • eyore

    eyore - 2008-12-21

    Well, I tried it (0.69RC2) with 6 extents in one target, and when I used the format command from Open Solaris, it found only the first extent. Danmero told me that only one extent/device per target is allowed.

    NHA

     
  • eyore

    eyore - 2008-12-21

    Well, I tried it (0.69RC2) with 6 extents in one target, and when I used the format command from Open Solaris, it found only the first extent. Danmero told me that only one extent/device per target is allowed.

    NHA

     
  • Volker

    Volker - 2008-12-21

    Hi,

    OK, maybe a bug in the iSCSI target code or something else, but defining multiple devices/extends is allowed as described in the docs. So if you knew that you can only select one extent/device.

    Regards
    Volker

     
  • Dan Merschi

    Dan Merschi - 2008-12-21

    Hi Volker
    The netbsd-iscsi FAQ is not very clear at this point.

    From FAQ "A device is made up of one or more extents, and/or one or more other devices."
    Conclusion: "devices" can be used to create combination of "extents" or "devices"

    But I don't see anywhere that we can use "target" to create combination.

    IMHO we need re-think this option.

     
  • Volker

    Volker - 2008-12-21

    --> At the highest level, a target is what is presented to the initiator,
    and is made up of one or more devices, and/or one or more extents.

    Regards
    Volker

     
  • Dan Merschi

    Dan Merschi - 2008-12-22

    I can duplicate this problem.
    Create multiple extents, different sizes, extent1=125MB, extent2=100MB, extent3=150MB.
    Create one target using this 3 extents, export.
    Attach the target using iSCSI initiator.
    Add disk, and the size is 125MB.

     

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