Users Guide

A critical part of this process is for ehcmd to issue an iscsiadm –m node –R –T iqn command to direct the Open iSCSI software
to rescan all of the block-mode devices so that the attributes (especially the size) for those devices are updated. If this command is slow,
you might see ehcmcli diagnostic information similar to the following output:
========================================================
Volume list
========================================================
Volume: user2
Target name: iqn.2001-05.com:0-8a0906-fde687707-60f1eeafe8a4d260-user2
Device to mount: /dev/mapper/eql-0-8a0906-fde687707-60f1eeafe8a4d260-user2
Status: Unable to build Device Mapper tables with the correct
capacity
Resolution: If this situation persists, use 'iscsiadm -m session --rescan',
and restart the ehcmd daemon.
Session: 4060 /dev/sdc 192.x.x.xv -> 192.x.x.xx 00:00:12
Session: 4061 /dev/sde 192.x.x.zz -> 192.x.x.xx 00:00:12
Session: 4064 /dev/sdh 192.x.x.zz -> 192.x.x.xy 00:00:12
Session: 4063 /dev/sdg 192.x.x.xv -> 192.x.x.yy 00:00:12
Session: 4053 /dev/sdb 192.x.x.zz -> 192.x.x.yy 00:00:12
Session: 4052 /dev/sdd 192.x.x.xv -> 192.x.x.yz 00:00:12
This information indicates that ehcmd continues trying to rebuild the devices using the larger size.
However, if ehcmd has tried repeatedly and failed, you might see ehcmcli diagnostic information like the following:
========================================================
Volume list
========================================================
Volume: user2
Target name: iqn.2001-05.com:0-8a0906-fde687707-60f1eeafe8a4d260-user2
Device to mount: /dev/mapper/eql-0-8a0906-fde687707-60f1eeafe8a4d260-user2
Status: WARNING: Unable to build Device Mapper tables with the correct
capacity
Resolution: Use 'iscsiadm -m session --rescan', and restart the ehcmd
daemon.
Session: 4060 /dev/sdc 192.x.x.xv -> 192.x.x.xx 00:00:12
Session: 4061 /dev/sde 192.x.x.zz -> 192.x.x.xx 00:00:12
Session: 4064 /dev/sdh 192.x.x.zz -> 192.x.x.xy 00:00:12
Session: 4063 /dev/sdg 192.x.x.xv -> 192.x.x.yy 00:00:12
Session: 4053 /dev/sdb 192.x.x.zz -> 192.x.x.yy 00:00:12
Session: 4052 /dev/sdd 192.x.x.xv -> 192.x.x.yz 00:00:12
Should this condition occur, try issuing the iscsiadm –m node –R –T iqn command (where iqn is the full target string).
Alternatively, try issuing the iscsiadm –m session –R command to rescan all sessions that are currently logged in. If the iscsiadm
rescan operation succeeds, restart the ehcmd daemon. If restarting the daemon does not correct the problem, look at the iscsiadm error
diagnostics.
Logical Volume Manager (LVM) Considerations
If you are using Logical Volume Manager (LVM) to manage the disk space on your EqualLogic volumes, the following considerations can
apply. eqltune will automatically configure LVM to ignore all lower-tier EqualLogic devices. See EqualLogic Host Performance and Tuning
Suite (eqltune) for additional details.
LVM Filtering Rules for EqualLogic Devices
The EqualLogic Host Connection Manager daemon (ehcmd) and Auto-Snapshot Manager CLI (ASMCLI) create a number of DM devices,
some of which are "visible" and safe for LVM to access and use (for example, user-facing top-tier MPIO devices) and some of which are
"hidden" and should not be accessed by LVM (for example, ASMCLI-mounted snapshot Smart Copies and lower-tier MPIO devices).
Verify and Fix LVM Filters with eqltune
To confirm the proper LVM exclusion filter is set, run eqltune, which will review the filters set up in lvm.conf and detect a
criticalerror for all hidden devices that are not ignored (that is, removed) by the current LVM device filter. Run eqltune fix to
edit lvm.conf and add a rule to ensure all HIT/Linux hidden devices are properly ignored.
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Troubleshooting