Dynamic Root Disk Frequently Asked Questions (August 2010)

1-13. Q: If swconfig is not supported by DRD, and swinstall runs swconfig, will it work properly?
A: DRD defers the configuration part of an install operation, which remains inactive until the system image is booted. (This behavior is
similar to what happens when kernel software is installed.)
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1-14. Q: Does the cloned root disk (VG) contain same VGID as the original root VG?
A: The volume group will be vg00 when the clone is booted. It will have a different minor number than the original vg00.
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1-15. Q: How is lvmtab adjusted to reflect the new device name for the disk in vg00?
A: The copy of lvmtab on the cloned image is modified by the clone operation to contain information that will reflect the desired volume
groups when the clone is booted.
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1-16. Q: Do the DRD administration tools keep track of the active boot disk's host attachment, in particular SAN boot
disks?
A: The system administrator is responsible for choosing a disk that DRD can use. This would include any communication with the SAN to
assign the disk to a particular system.
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1-17. Q: What is the difference between DRD Hot Recovery and Mirror Disk/UX?
A: Mirror Disk/UX keeps an "always up to date" image of the booted system. Conversely, DRD provides a "point in time" image. The
booted system and the clone may then diverge due to changes to either one. Keeping the clone unchanged is the Hot Recovery
scenario. Note that DRD is not available for HP-UX 11.11, which limits your options on those systems.
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1-18. Q: Since I take a regular root disk and use it to boot another system, can I use the cloned disk I created with
DRD to boot another system?
A: It is possible to do this, however, factors such as machine personality (e.g., hostname, IP address, etc.) make this very difficult. HP
does not recommend using the cloned disk to boot another system.
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1-19. Q: What happens during a clone copy if, for example, /opt/xxxxx is mounted from /dev/vg01/lvolxxxx? Is the
content of /opt/xxxxx copied to the clone or does it only create its directory?
A: Only the contents of vg00 are copied. In the above example, the content of /opt/xxxxx will not be copied to the clone. A system that
has the /opt file systems (or any file system that is patched) not in vg00 is not suitable for use with DRD.
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1-20. Q: What are the effects of the clone copy on system operation (for example, performance)?
A: The I/O of the clone operation will have some impact, particularly if the disk is close to the booted system. For example, if the two disks
are on the same SCSI chain, then I/O to the clone will affect performance of I/O on the booted system. DRD's performance is similar to
system performance when using Ignite to create recovery images, which many system administrators find acceptable.
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1-21. Q: IgniteUX offers net and tape images. What is the advantage of DRD?
A: DRD provides a “make-disk-recovery” solution and has several advantages over IgniteUX net and tape images:
No tape drive is needed
No impact on network performance will occur
No security issues of transferring data across the network will occur
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1-22. Q:How can I be sure the patches I install are safe in a DRD environment?
A: You can install patches packaged in standard Software Distributor (SD) format. Most patches for HP–UX 11.23 September, 2004 and
above are DRD safe. However, the DRD product maintains a list of those patches known to be unsafe. When the revision of SD
required by DRD is run by drd runcmd, it makes sure that a patch does not appear in the list before installing or removing it.