Got SAN lun 0 without mapping any disk to the server

kankan55 · 01-02-2013, 10:12 PM

I just zoning the hba to the storage but didn't map any disk to the server yet. But I got lun0 appear on the /dev/disk/by-path/ . see below output.

/dev/disk/by-path:
total 0
lrwxrwxrwx 1 root root 9 Jan 3 04:04 pci-0000:00:1f.2-scsi-0:0:0:0 -> ../../sr0
lrwxrwxrwx 1 root root 9 Jan 3 04:04 pci-0000:04:00.0-scsi-0:0:0:0 -> ../../sda
lrwxrwxrwx 1 root root 10 Jan 3 04:04 pci-0000:04:00.0-scsi-0:0:0:0-part1 -> ../../sda1
lrwxrwxrwx 1 root root 10 Jan 3 04:04 pci-0000:04:00.0-scsi-0:0:0:0-part2 -> ../../sda2
lrwxrwxrwx 1 root root 10 Jan 3 04:04 pci-0000:04:00.0-scsi-0:0:0:0-part3 -> ../../sda3
lrwxrwxrwx 1 root root 9 Jan 3 04:04 pci-0000:0a:00.0-fc-0x5006016141e09ae7-lun-0 -> ../../sdc
lrwxrwxrwx 1 root root 9 Jan 3 04:04 pci-0000:0a:00.0-fc-0x5006016841e09ae7-lun-0 -> ../../sdb

How does the SAN lun 0 come from ? The OS is RHEL 6.3

kankan55 · 01-02-2013, 10:16 PM

nothing happened for fdisk and parted command

# parted /dev/sdb
# parted /dev/sdc
# fdisk -l /dev/sdb
# fdisk -l /dev/sdc

trijit · 01-03-2013, 01:16 AM

Quote:

Originally Posted by kankan55

I just zoning the hba to the storage but didn't map any disk to the server yet. But I got lun0 appear on the /dev/disk/by-path/ . see below output.

/dev/disk/by-path:
total 0
lrwxrwxrwx 1 root root 9 Jan 3 04:04 pci-0000:00:1f.2-scsi-0:0:0:0 -> ../../sr0
lrwxrwxrwx 1 root root 9 Jan 3 04:04 pci-0000:04:00.0-scsi-0:0:0:0 -> ../../sda
lrwxrwxrwx 1 root root 10 Jan 3 04:04 pci-0000:04:00.0-scsi-0:0:0:0-part1 -> ../../sda1
lrwxrwxrwx 1 root root 10 Jan 3 04:04 pci-0000:04:00.0-scsi-0:0:0:0-part2 -> ../../sda2
lrwxrwxrwx 1 root root 10 Jan 3 04:04 pci-0000:04:00.0-scsi-0:0:0:0-part3 -> ../../sda3
lrwxrwxrwx 1 root root 9 Jan 3 04:04 pci-0000:0a:00.0-fc-0x5006016141e09ae7-lun-0 -> ../../sdc
lrwxrwxrwx 1 root root 9 Jan 3 04:04 pci-0000:0a:00.0-fc-0x5006016841e09ae7-lun-0 -> ../../sdb

How does the SAN lun 0 come from ? The OS is RHEL 6.3

Do you have multipath installed? If so, run "multipath -ll"

Also, paste the output of "fdisk -l"

For Netapp(if netapp santoolkit is installed), run "sanlun lun show"
For EMC, run "powermt display dev=all"

Please share the outpur.

kankan55 · 01-03-2013, 01:46 AM

Hi trijit

The storage model is EMC cx3-20f. The powerpath is not installed on the server.
I have read this link and it said that it's LUNZ (required by EMC).

Quote:

[root@RHEL6 ~]# multipath -ll
Jan 03 07:40:13 | DM multipath kernel driver not loaded
Jan 03 07:40:13 | /etc/multipath.conf does not exist, blacklisting all devices.
Jan 03 07:40:13 | A sample multipath.conf file is located at
Jan 03 07:40:13 | /usr/share/doc/device-mapper-multipath-0.4.9/multipath.conf
Jan 03 07:40:13 | You can run /sbin/mpathconf to create or modify /etc/multipath.conf
Jan 03 07:40:13 | DM multipath kernel driver not loaded

Quote:

[root@RHEL6 ~]# fdisk -l

Disk /dev/sda: 73.4 GB, 73372631040 bytes
255 heads, 63 sectors/track, 8920 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x09795236

Device Boot Start End Blocks Id System
/dev/sda1 * 1 66 524288 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 66 1959 15204352 8e Linux LVM
/dev/sda3 1959 8921 55922688 8e Linux LVM

Disk /dev/mapper/rootvg-rootlv: 6450 MB, 6450839552 bytes
255 heads, 63 sectors/track, 784 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/rootvg-swaplv: 2147 MB, 2147483648 bytes
255 heads, 63 sectors/track, 261 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/datavg-datalv: 57.3 GB, 57260638208 bytes
255 heads, 63 sectors/track, 6961 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/rootvg-varlv: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/rootvg-homelv: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/rootvg-perflv: 524 MB, 524288000 bytes
255 heads, 63 sectors/track, 63 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/rootvg-tmplv: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

[root@RHEL6 ~]#

trijit · 01-03-2013, 02:51 AM

Quote:

Originally Posted by kankan55

Hi trijit

The storage model is EMC cx3-20f. The powerpath is not installed on the server.
I have read this link and it said that it's LUNZ (required by EMC).

Thanks for the outputs.

You can get rid of this LUNZ by setting arraycommpath to 0. But I'd say this is not a good solution at all. Because setting this value may cause powerpath not to recognize devices. Instead, you can just assign a new LUN to the host group on the ex3 side and simply change the LUN id to 0. This should overlap the LUNZ currently you are seeing.

Let me know if that works.

Thanks.

trijit · 01-03-2013, 03:40 AM

Quote:

Originally Posted by trijit

Thanks for the outputs.

You can get rid of this LUNZ by setting arraycommpath to 0. But I'd say this is not a good solution at all. Because setting this value may cause powerpath not to recognize devices. Instead, you can just assign a new LUN to the host group on the ex3 side and simply change the LUN id to 0. This should overlap the LUNZ currently you are seeing.

Let me know if that works.

Thanks.

Also, user multipath after assigning a LUN. Set friendly names in multipath.conf as true. Seems, it's already installed on your system but not started. The startup script should be in /etc/init.d/multipathd.