Using the Nytro XD Device Node Under Nytro XD
NOTE This is a Linux-specific chapter. Windows users need not perform any additional steps.
Nytro XD creates the device mapper device nodes with the same names as the underlying VD names, but with an additional nytroxd- prefix. This device node is placed under the /dev/mapper directory. This is true for all of the partitions that exist on the VD configured in Nytro XD. Nytro XD creates mapping device nodes under /dev/mapper with the nytroxd- prefix for each of those partitions. When a VD is successfully added to Nytro XD, it automatically runs kpartx/partprobe to create these nodes.
For example: If you issue the following command to configure a VD,
Corresponding to the VD, /dev/disk/by-id/scsi-0x5000c5000f8f8c1f, Nytro XD creates a node, /dev/mapper/nytroxd-scsi-0x5000c5000f8f8c1f, which represents the cached VD. You can find the new device node path using the MSM XD -VdList command.
Device Node: /dev/disk/by-id/scsi-35000c5000f8f8c1f [/dev/sdm]
Mapped Path: /dev/mapper/nytroxd-scsi-35000c5000f8f8c1f
If /etc/fstab contains the following entry:
/dev/disk/by-id/scsi-35000c5000f8f8c1f /data ext4 defaults 1 2
it must be changed into the following entry:
/dev/mapper/nytroxd-scsi-35000c500f8f8c1f /data ext4 defaults 1 2
WARNING When Nytro XD creates a device mapper device node for a VD (for example, /dev/mapper/nytroxd-scsi-35000c5001d70ae43), the same VD is also available for direct access (through /dev/disk/by-id/scsi-35000c5001d70ae43, which usually is a symbolic link to the underlying sd device under /dev, for example, /dev/sdg). Even when a cache device (WarpDrive) is configured under Nytro XD, the device node for that (for example, /dev/sdb) is also available for direct access. Exercise caution and make sure that you do not inadvertently directly access or update these disks outside of the Nytro XD control. Such an access is illegal, and any updates made through the direct access can lead to data corruption on these disks. Be aware that this is a feature/limitation of the Linux device model.
DB15-000917-01 - July 2012 |
Copyright© 2012 by LSI Corporation. All rights reserved. Advance copy – Not for General Distribution. |