> [r...@core26 ~]# multipath -ll
> > sda: checker msg is "rdac checker reports path is down"
> > iscsi06-apoio1 (3600a0b80003ad1e500000f2e49ae6d3e) dm-0 IBM,VirtualDisk
> > [size=2.7T][features=1 queue_if_no_path][hwhandler=0]
> Very interesting: Out SAN system allows only 2048 GB of storage per LUN.
> Lookinginto the SCSI protocol, it seems there is a 32bit number of blocks
> (512Bytes) to count the LUN capacity. Thus roughly 4Gig times 0.4kB makes
> 2TB. I
> wonder how your system represents 2.7TB in the SCSI protocol.

Is this 2048 GB limit imposed on iSCSI? Because there is nothing in SCSI
itlself which forces you to this limit... Nowadays, you could have huge
partitions (if you do GPT partitions with PARTED)... So, if there is a
limit, it should come from iSCSI...

> > [r...@core26 ~]# fdisk -l /dev/sdb1
> > Disk /dev/sdb1: 499.9 GB, 499999983104 bytes
> Isn't that a bit small for 2.7TB ? I think you should use fdisk on the
> disk, not
> on the partition!

Here goes the output of fdisk on the disk:

 [r...@core26 ~]# fdisk -l /dev/sdb
WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'! The util fdisk
doesn't support GPT. Use GNU Parted.
Disk /dev/sdb: 2998.9 GB, 2998998663168 bytes
255 heads, 63 sectors/track, 364607 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1      267350  2147483647+  ee  EFI GPT

We do GPT partitions with parted in order to overcome the deficienty of the
(old!) 2048GB limit. Here goes the output of a parted (just to be sure):

[r...@core26 ~]# parted /dev/mapper/iscsi06-apoio2
GNU Parted 1.8.1
Using /dev/mapper/iscsi06-apoio2
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print
Model: Linux device-mapper (dm)
Disk /dev/mapper/iscsi06-apoio2: 2999GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number  Start   End    Size   File system  Name            Flags
 1      17.4kB  500GB  500GB  ext3         iscsi06-apoio2

> [r...@core26 ~]# df -k
> > Filesystem           1K-blocks      Used Available Use% Mounted on
> > /dev/sda1             90491396   2008072  83812428   3% /
> > tmpfs                   524288         0    524288   0% /dev/shm
> > /dev/mapper/iscsi06-apoio1p1
> >                      480618344    202804 456001480   1% /apoio06-1
> > /dev/mapper/iscsi06-apoio2p1
> >                      480618344    202800 456001484   1% /apoio06-2
> >
> > The sizes, although not exactly the same (but that doesn't happen also
> for
> > the system disk), are very close.
> So you have roughly 500GB on a 2.7TB LUN in use.

That is right... I have a logical volume of  2.7TB but a partition of 500GB.
But isn't this allowed?

> I do not think the difference I see in previous commands is big enough to
> justify a wrong setup. But I'm just guessing and I'm not really an expert.

It now depends where the partition is located on the disk (use a corrected
> fdisk
> invocation to find out).

In principle, the partitition should be on the beguining of the logical
volume but I can not confirm it with parted. If this is the case, everything
shoudl work fine. However, If there is the limit of 2048 GB of storage per
LUN, this may confuse the setup.. don't know for sure.

Cheers and Thanks

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