System information

Pro ced u re 25.1. En su rin g a Clean D evice Remo val
1. Close all users of the device and backup device data as needed.
2. Use umo unt to unmount any file systems that mounted the device.
3. Remove the device from any md and LVM volume using it. If the device is a member of an LVM
Volume group, then it may be necessary to move data off the device using the pvmo ve
command, then use the vg red uce command to remove the physical volume, and (optionally)
pvremo ve to remove the LVM metadata from the disk.
4. If the device uses multipathing, run mul ti path -l and note all the paths to the device.
Afterwards, remove the multipathed device using mul ti path -f d evi ce.
5. Run bl o ckd ev --fl ushbufs device to flush any outstanding I/O to all paths to the
device. This is particularly important for raw devices, where there is no umo unt or vg red uce
operation to cause an I/O flush.
6. Remove any reference to the device's path-based name, like /d ev/sd , /d ev/d i sk/by-
path or the majo r: mi no r number, in applications, scripts, or utilities on the system. This is
important in ensuring that different devices added in the future will not be mistaken for the
current device.
7. Finally, remove each path to the device from the SCSI subsystem. To do so, use the command
echo 1 > /sys/bl o ck/device-name/d evi ce/d el ete where device-name may be
sd e, for example.
Another variation of this operation is echo 1 >
/sys/cl ass/scsi _d evi ce/h: c: t: l/d evi ce/d el ete, where h is the HBA number, c is
the channel on the HBA, t is the SCSI target ID, and l is the LUN.
Note
The older form of these commands, echo "scsi remo ve-si ng l e-d evi ce 0 0 0
0 " > /pro c/scsi /scsi , is deprecated.
You can determine the device-name, HBA number, HBA channel, SCSI target ID and LUN for a
device from various commands, such as l sscsi , scsi _i d , mul ti path -l , and l s -l
/d ev/d i sk/by-*.
After performing Procedure 25.1, “Ensuring a Clean Device Removal” , a device can be physically
removed safely from a running system. It is not necessary to stop I/O to other devices while doing so.
Other procedures, such as the physical removal of the device, followed by a rescan of the SCSI bus
(as described in Section 25.9, “ Scanning Storage Interconnects” ) to cause the operating system
state to be updated to reflect the change, are not recommended. This will cause delays due to I/O
timeouts, and devices may be removed unexpectedly. If it is necessary to perform a rescan of an
interconnect, it must be done while I/O is paused, as described in Section 25.9, “ Scanning Storage
Interconnects” .
25.5. Removing a Pat h t o a St orage Device
If you are removing a path to a device that uses multipathing (without affecting other paths to the
device), then the general procedure is as follows:
⁠Chapt er 2 5. O nline St orag e Manag ement
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