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ManualsBrandsRed Hat ManualsComputer equipmentENTERPRISE LINUX - ONLINE STORAGE RECONFIGURATION GUIDE BETA
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servi ce tg td start
St o p p in g t he t g t d service
To stop the tgtd service, run:
servi ce tg td sto p
If there are open connections, use:
servi ce tg td fo rce-sto p
Warning
Using this command will terminate all target arrays.
25.3. Persist ent Naming
The operating system issues I/O to a storage device by referencing the path that is used to reach it.
For SCSI devices, the path consists of the following:
PCI identifier of the host bus adapter (HBA)
channel number on that HBA
the remote SCSI target address
the Logical Unit Number (LUN)
This path-based address is not persistent. It may change any time the system is reconfigured (either
by on-line reconfiguration, as described in this manual, or when the system is shutdown,
reconfigured, and rebooted). It is even possible for the path identifiers to change when no physical
reconfiguration has been done, as a result of timing variations during the discovery process when
the system boots, or when a bus is re-scanned.
The operating system provides several non-persistent names to represent these access paths to
storage devices. One is the /d ev/sd name; another is the majo r: mi no r number. A third is a
symlink maintained in the /d ev/d isk/by-path/ directory. This symlink maps from the path
identifier to the current /d ev/sd name. For example, for a Fibre Channel device, the PCI info and
Host: BusTarget: LUN info may appear as follows:
pci-0000:02:0e.0-scsi-0:0:0:0 -> ../../sda
For iSCSI devices, by-path/ names map from the target name and portal information to the sd
name.
It is generally not appropriate for applications to use these path-based names. This is because the
storage device these paths reference may change, potentially causing incorrect data to be written to
the device. Path-based names are also not appropriate for multipath devices, because the path-
based names may be mistaken for separate storage devices, leading to uncoordinated access and
unintended modifications of the data.
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