Disksuite Replacing a failed bootdisk
In the following example, the host has a failed bootdisk (c0t0d0). Fortunately, the system is using DiskSuite, with a mirror at c0t1d0. The following sequence of steps can be used to restore the system to full redundancy.System fails to boot
When the system attempts to boot, it fails to find a valid device as required by the boot-device path at device alias "disk". It then attempts to boot from the network:
screen not found. Can't open input device. Keyboard not present. Using ttya for input and output. Sun Ultra 30 UPA/PCI (UltraSPARC-II 296MHz), No Keyboard OpenBoot 3.27, 512 MB memory installed, Serial #9377973. Ethernet address 8:0:20:8f:18:b5, Host ID: 808f18b5. Initializing Memory Timeout waiting for ARP/RARP packet Timeout waiting for ARP/RARP packet Timeout waiting for ARP/RARP packet ...
Boot from mirror
At this point, the administrator realizes that the boot disk has failed, and queries the device aliases to find the one corresponding to the disksuite mirror:
ok devalias sds-mirror /pci@1f,4000/scsi@3/disk@1,0 sds-root /pci@1f,4000/scsi@3/disk@0,0 net /pci@1f,4000/network@1,1 disk /pci@1f,4000/scsi@3/disk@0,0 cdrom /pci@1f,4000/scsi@3/disk@6,0:f ...
The administrator then boots the system from the mirror device "sds-mirror":
ok boot sds-mirror
The system starts booting off of sds-mirror. However, because there are only two of the original four state database replicas available, a quorum is not achieved. The system requires manual intervention to remove the two failed state database replicas:
Starting with DiskSuite 4.2.1, an optional /etc/system parameter exists which allows DiskSuite to boot with just 50% of the state database replicas online. For example, if one of the two boot disks were to fail, just two of the four state database replicas would be available. Without this /etc/system parameter (or with older versions of DiskSuite), the system would complain of "insufficient state database replicas", and manual intervention would be required on bootup. To enable the "50% boot" behaviour with DiskSuite 4.2.1, execute the following command:
# echo "set md:mirrored_root_flag=1" >> /etc/system
Boot device: /pci@1f,4000/scsi@3/disk@1,0 File and args: SunOS Release 5.8 Version Generic_108528-07 64-bit Copyright 1983-2001 Sun Microsystems, Inc. All rights reserved. WARNING: md: d10: /dev/dsk/c0t0d0s0 needs maintenance WARNING: forceload of misc/md_trans failed WARNING: forceload of misc/md_raid failed WARNING: forceload of misc/md_hotspares failed configuring IPv4 interfaces: hme0. Hostname: pegasus metainit: pegasus: stale databases Insufficient metadevice database replicas located. Use metadb to delete databases which are broken. Ignore any "Read-only file system" error messages. Reboot the system when finished to reload the metadevice database. After reboot, repair any broken database replicas which were deleted. Type control-d to proceed with normal startup, (or give root password for system maintenance): ****** single-user privilege assigned to /dev/console. Entering System Maintenance Mode Oct 17 19:11:29 su: 'su root' succeeded for root on /dev/console Sun Microsystems Inc. SunOS 5.8 Generic February 2000 # metadb -i flags first blk block count M p unknown unknown /dev/dsk/c0t0d0s5 M p unknown unknown /dev/dsk/c0t0d0s6 a m p lu 16 1034 /dev/dsk/c0t1d0s5 a p l 16 1034 /dev/dsk/c0t1d0s6 o - replica active prior to last mddb configuration change u - replica is up to date l - locator for this replica was read successfully c - replica's location was in /etc/lvm/mddb.cf p - replica's location was patched in kernel m - replica is master, this is replica selected as input W - replica has device write errors a - replica is active, commits are occurring to this replica M - replica had problem with master blocks D - replica had problem with data blocks F - replica had format problems S - replica is too small to hold current data base R - replica had device read errors # metadb -d c0t0d0s5 c0t0d0s6 metadb: pegasus: /etc/lvm/mddb.cf.new: Read-only file system # metadb -i flags first blk block count a m p lu 16 1034 /dev/dsk/c0t1d0s5 a p l 16 1034 /dev/dsk/c0t1d0s6 o - replica active prior to last mddb configuration change u - replica is up to date l - locator for this replica was read successfully c - replica's location was in /etc/lvm/mddb.cf p - replica's location was patched in kernel m - replica is master, this is replica selected as input W - replica has device write errors a - replica is active, commits are occurring to this replica M - replica had problem with master blocks D - replica had problem with data blocks F - replica had format problems S - replica is too small to hold current data base R - replica had device read errors # reboot -- sds-mirror
Check extent of failures
Once the reboot is complete, the administrator then logs into the system and checks the status of the DiskSuite metadevices. Not only have the state database replicas failed, but all of the DiskSuite metadevices previously located on device c0t0d0 need to be replaced. Clearly the disk has completely failed.
pegasus console login: root Password: ****** Oct 17 19:14:03 pegasus login: ROOT LOGIN /dev/console Last login: Thu Oct 17 19:02:42 from rambler.wakefie Sun Microsystems Inc. SunOS 5.8 Generic February 2000 # metastat d0: Mirror Submirror 0: d10 State: Needs maintenance Submirror 1: d20 State: Okay Pass: 1 Read option: roundrobin (default) Write option: parallel (default) Size: 13423200 blocks d10: Submirror of d0 State: Needs maintenance Invoke: metareplace d0 c0t0d0s0 <new device> Size: 13423200 blocks Stripe 0: Device Start Block Dbase State Hot Spare c0t0d0s0 0 No Maintenance d20: Submirror of d0 State: Okay Size: 13423200 blocks Stripe 0: Device Start Block Dbase State Hot Spare c0t1d0s0 0 No Okay d1: Mirror Submirror 0: d11 State: Needs maintenance Submirror 1: d21 State: Okay Pass: 1 Read option: roundrobin (default) Write option: parallel (default) Size: 2100000 blocks d11: Submirror of d1 State: Needs maintenance Invoke: metareplace d1 c0t0d0s1 <new device> Size: 2100000 blocks Stripe 0: Device Start Block Dbase State Hot Spare c0t0d0s1 0 No Maintenance d21: Submirror of d1 State: Okay Size: 2100000 blocks Stripe 0: Device Start Block Dbase State Hot Spare c0t1d0s1 0 No Okay d4: Mirror Submirror 0: d14 State: Needs maintenance Submirror 1: d24 State: Okay Pass: 1 Read option: roundrobin (default) Write option: parallel (default) Size: 2100000 blocks d14: Submirror of d4 State: Needs maintenance Invoke: metareplace d4 c0t0d0s4 <new device> Size: 2100000 blocks Stripe 0: Device Start Block Dbase State Hot Spare c0t0d0s4 0 No Maintenance d24: Submirror of d4 State: Okay Size: 2100000 blocks Stripe 0: Device Start Block Dbase State Hot Spare c0t1d0s4 0 No Okay
The administrator replaces the failed disk with a new disk of the same geometry. Depending on the system model, the disk replacement may require that the system be powered down. The replacement disk is then partitioned identically to the mirror, and state database replicas are copied onto the replacement disk. Finally, the metareplace command copies that data from the mirror to the replacement disk, restoring redundancy to the system.
# prtvtoc /dev/rdsk/c0t1d0s2 | fmthard -s - /dev/rdsk/c0t0d0s2 fmthard: New volume table of contents now in place. # installboot /usr/platform/sun4u/lib/fs/ufs/bootblk /dev/rdsk/c0t0d0s0 # metadb -f -a /dev/dsk/c0t0d0s5 # metadb -f -a /dev/dsk/c0t0d0s6 # metadb -i flags first blk block count a u 16 1034 /dev/dsk/c0t0d0s5 a u 16 1034 /dev/dsk/c0t0d0s6 a m p luo 16 1034 /dev/dsk/c0t1d0s5 a p luo 16 1034 /dev/dsk/c0t1d0s6 o - replica active prior to last mddb configuration change u - replica is up to date l - locator for this replica was read successfully c - replica's location was in /etc/lvm/mddb.cf p - replica's location was patched in kernel m - replica is master, this is replica selected as input W - replica has device write errors a - replica is active, commits are occurring to this replica M - replica had problem with master blocks D - replica had problem with data blocks F - replica had format problems S - replica is too small to hold current data base R - replica had device read errors # metareplace -e d0 c0t0d0s0 d0: device c0t0d0s0 is enabled # metareplace -e d1 c0t0d0s1 d1: device c0t0d0s1 is enabled # metareplace -e d4 c0t0d0s4 d4: device c0t0d0s4 is enabled
Once the resync process is complete, operating system redundancy has been restored.
No comments:
Post a Comment