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How to rescan the SCSI bus to add or remove a SCSI device without rebooting the computer

Updated 2014-04-09T16:06:37+00:00

Issue

  • Is it possible to add or remove a SCSI device without rebooting a running system?
  • Can you scan a SCSI bus for new or missing SCSI devices without rebooting?
  • How can I make newly connected SCSI devices available without rebooting?
  • What is the Linux equivalent to the Solaris command devfsadm to add or remove storage devices?
  • I am trying to add a LUN to a live system but it is not recognized
  • I am trying to add a tape drive to a live system but it is not recognized
  • I am trying to add a disk drive to a live system but it is not recognized
  • How can I force a rescan of my SAN to find newly associated LUNs?
  • What to do if a newly allocated LUN on my SAN is not available?
  • Unable to probe for a newly allocated LUN

Environment

  • Red Hat Enterprise Linux 5.0 or above   
    • SCSI devices over a Fibre Channel or iSCSI transport

Technical support for online storage reconfiguration is provided on Red Hat Enterprise Linux 5 and above. Limited tools for hot adding and removing storage are present in previous releases of Red Hat Enterprise Linux, however, they cannot be guaranteed to work correctly in all configurations.  Red Hat Enterprise Linux 5 includes many enhancements to udev, the low level device drivers, SCSI midlayer, and device-mapper multipath, which enables comprehensive support for online storage reconfiguration.

This article, the Online Storage Reconfiguration Guide, and the Storage Administration Guide currently cover the FC and iSCSI transports. Future versions of this documentation will cover other SCSI transports, such as SAS and FCoE.

Hewlett-Packard Smart Array controllers that use the cciss driver provide a different interface for manipulating SCSI devices. Users of this hardware can find a similar guide here.

The procedures below also apply to hypervisors (i.e. "dom0" in Red Hat Enterprise Linux 5 virtualization), but the procedures are different for dynamically altering the storage of running virtual guests. For more information about adding storage to virtual guests, see the Virtualization Guide.

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