Seagate ST34572WC Specifications

1 When Good Disks Go Bad: Dealing with Disk Failures Under LVM Abstract ...

10 Disk Failure Notification Messages from Diagnostics If you have Event Monitoring Service (EMS) hardware monitors installed on your system, and yo

11 # vgdisplay -v vg vgdisplay: Warning: couldn't query physical volume "/dev/dsk/c0t3d0": The specified path does not correspond to

12 3. Confirming Disk Failure Once you suspect a disk has failed or is failing, make certain that the suspect disk is indeed failing. Replacing or re

13 5. If both ioscan and diskinfo succeed, the disk might still be failing. As a final test, try to read from the disk using the dd command. Depen

14 For a version 2.x VG, enter: xd -j 0x21a4 -t uI -N 4 /dev/dsk/c0t3d0 In this example, this is a version 1.0 VG. # xd -j 0x2048 -t uI -N 4 /dev/

15 4. Gathering Information About a Failing Disk Once you know which disk is failing, you can decide how to deal with it. You can choose to remove

16 /dev/vg00/lvol2 512 512 /dev/vg00/lvol3 50 50 /dev/vg00/lvol4 50 50 /dev/vg00/l

17 There might be an instance where you see that only the failed physical volume holds the current copy of a given extent (and all other mirror copi

18 5. Removing the Disk If you have a copy of the data on the failing disk, or you can move the data to another disk, you can choose to remove the d

19 In these situations where the disk was not available at boot time, or the disk has failed before volume group activation (pvdisplay failed), the l

2 New Options to Specify the DSF Naming Model ... 44 Behavioral Differenc

20 You can select a particular target disk or disks, if desired. For example, to move all the physical extents from c0t5d0 to the physical volume c0t

21 groups were configured with only persistent device special files, there is no need to arrange them again. On releases prior to HP-UX 11i v3, you m

22 7. 6. Replacing the Disk (Releases Prior to 11i v3 or When LVM Volume Group is Configured with Only Legacy DSFs on 11i v3 or Later) If you decid

23 # fuser –ku /dev/vgname/lvname 4. Then try to unmount the file system again as follows: # umount /dev/vgname/lvname o If the logical vol

24 If the disk is hot-swappable, you can replace it without powering down the system. Otherwise, power down the system before replacing the disk. For

25 The vgchange command attaches all paths for all disks in the volume group, and automatically resumes recovering any unattached failed disks in the

26 Swap: lvol2 on: /dev/dsk/c0t5d0 Dump: lvol2 on: /dev/dsk/c0t5d0, 0 # pvdisplay –v /dev/dsk/c2t15d0 | more … --- Distributi

27 # umount /dev/vg01/lvol1 umount: cannot unmount /dump : Device busy # fuser -u /dev/vg01/lvol1 /dev/vg01/lvol1: 27815c(root) 27184c(root)

28 # newfs [options] /dev/vg01/rlvol1 # mount /dev/vg01/lvol1 /app # <restore the file system from backup> Disk Replacement Process Flowcha

29 StartIs Disk ReplacedCheck Disk is Okay Is Disk Okay ?Check Data on Disk (use fstyp(1M))Data on Disk ?Get the VG name to which the PV belongs toIs

3 Abstract This white paper discusses how to deal with disk failures under the HP-UX Logical Volume Manager (LVM). It is intended for system administ

30 Check Root DiskRoot Disk?YesIs Primary root mirrored?YesBoot from MirrorBCH>boot altISL>hpux -lqIgnite/UX Recovery Recover from a Recovery t

31 8. 7. Replacing the Disk (11i v3 release Onwards when the LVM Volume Group is Configured with Persistent DSFs) After you isolate a failed disk,

32 # scsimgr replace_wwid –D /dev/rdisk/disk14 This command lets the storage subsystem replace the old disk’s LUN World-Wide-Identifier (WWID) with

33 # vgchange -a y /dev/vgnn Note: The vgchange command with the -a y option can be run on a volume group that is deactivated or already activated. I

34 b. If fuser reports process IDs using the logical volume, use the ps command to map the list of process IDs to processes, and determine whether y

35 In this example, LUN instance 28 was created for the new disk, with LUN hardware path 64000/0xfa00/0x1c, device special files /dev/disk/disk28 and

36 o For raw volumes, restore the full raw volume using the utility that was used to create your backup. Then restart the application. o For file s

37 Note: On an HP 9000 server, the boot disk is not partitioned so the physical volume refers to the entire disk, not the HP-UX partition. Enter the

38 In this example, LUN instance 28 was created for the new disk, with LUN hardware path 64000/0xfa00/0x1c, device special files /dev/disk/disk28 and

39 the volume group that were replaced. Therefore, run vgchange only after all work has been completed on all disks and paths in the volume group, an

4 1. Preparing for Disk Recovery Forewarned is forearmed. Knowing that hard disks will fail eventually, you can take some precautionary measures t

40 StartIs Disk ReplacedCheck Disk is Okay Is Disk Okay ?Check Data on Disk (use fstyp(1M))Data on Disk ?Get the VG name to which the PV belongs toIs

41 Check Root DiskRoot Disk?YesIs Primary root mirrored?YesBoot from MirrorBCH>boot altISL>hpux -lqIgnite/UX Recovery Recover from a Recovery t

42 Conclusion In your role as system manager, you will encounter disk failures. LVM can lessen the impact of those disk failures, enabling you to con

43 Appendix A: Using Device File Types Prior to the HP-UX 11i v3 release, there were only legacy device special files. Starting with the HP-UX 11i v3

44 Appendix B: Device Special File Naming Model HP-UX 11i v3 introduces a new representation of mass storage devices called the agile view. In this r

45 vgimport –N Configure the volume group using persistent DSFs. You can only use this option together with the scan option, –s. In the absence of th

46 Appendix C: Volume Group Versions and LVM Configuration Files Volume Group Version With the March 2008 release of HP-UX 11i v3, LVM supports a new

47 lvmtab, lvmtab_p LVM has a well known configuration file /etc/lvmtab. With the introduction of Version 2.x volume groups, LVM uses a new configu

48 Appendix D: Procedures This section contains details on some of the procedures described in earlier sections of this document. Mirroring the Root

49 contains two physical volumes, and one of them is not accessible, the system rejects to boot unless you disable the quorum check using the –lq opt

5 Starting with the HP-UX 11i v3 release, HP no longer requires or recommends that you configure LVM with alternate links. However, it is possible t

50 Mirroring the Root Volume on Integrity Servers The procedure to mirror the root disk on Integrity servers is similar to the procedure for PA-RISC

51 You now have the following device files for this disk: /dev/disk/disk75 The entire disk (block access) /dev/rdisk/disk75 The entire disk (chara

52 # echo “boot vmunix” > ./AUTO b. Copy the file from the current directory into the new disk EFI partition. Be sure to use the device file w

53 10. Specify the mirror disk as the alternate boot path in nonvolatile memory: # setboot –a 0/1/1/0.1.0 11. To add a line to /stand/bootconf for

54 Appendix E: LVM Error Messages This appendix lists some of the warning and error messages reported by LVM. For each message, the cause is listed,

55 Max PV 16 Cur PV 1 Act PV 1 Max PE per PV 4350

56 pvchange "a": Illegal option. Cause: LVM OLR is not installed. Recommended Action: Install the patches enabling LVM OLR, or u

57 overwritten with a command like dd or pvcreate. If the disk is shared between two systems, it is likely that one of the systems was not aware that

58 /dev/dsk/c40t0d4 (02) !VGID:35c8cf58 3f8df316 PVID:065f303f 3e63f003 /dev/dsk/c40t1d0 … In this example, note that the volume group ids (VG

59 vgdisplay vgdisplay: Couldn't query volume group "/dev/vg00". Possible error in the Volume Group minor number; Please check

6 # swlist -l fileset | grep -i mirror LVM.LVM-MIRROR-RUN B.11.23 LVM Mirror The process of mirroring is usually straightforward, and can be easily

60 Recommended Action: The volume group extent size and number of physical extents per disk are not dynamic. The only way to use the entire disk is

61 Appendix F: Moving a Root Disk to a New Disk or Another Disk Follow these steps to move root disk /dev/dsk/c1t1d1 (source disk) to disk /dev/dsk/

62 Appendix G: Recreating Volume Group Information There might be situations when the volume group directory, for example vgtest under /dev, is accid

63 Appendix H: Disk Relocation and Recovery Using vgexport and vgimport Follow these steps to move a volume group /disks from one system (for example

64 using vgimport command, followed by configuring the LVM with legacy device special files as well using vgextend command. If you choose to use the

65 Appendix I: Splitting Mirrors to Perform Backups Make sure the database is not active before you split it. The following example uses /dev/vg02/lv

66 Appendix J: Moving an Existing Root Disk to a New Hardware Path Before you shut down the system, note the /etc/lvmtab contents, and note which dis

67 For more information To learn more about some of the LVM features, see the following documents on the HP documentation website: http://docs.hp.co

7 disks in any volume group leads to a more complex LVM configuration, which will be more difficult to recreate after a catastrophic failure. Finally

8 While this list of preparatory actions does not keep a disk from failing, it makes it easier for you to deal with failures when they occur.

9 2. Recognizing a Failing Disk The guidelines in the previous section will not prevent disk failures on your system. Assuming you follow all the rec