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FAQ:
How to setup Disk Suite(SDS) Mirrors
for Root, Swap, and data via the command line.
By Colin A. Bitterfield
EX-SUN Microsystems, Inc.
Contact Me
Step 1: Setup proper slices
Suggestions for a 36GB drive, use the same partition table for both drives.
0 [root] 4GB
1 [swap] 4GB
2 [backup] -
3 /export/home 4GB
4 /data (Remainer)
5 open
6 open
7 [meta devices] (last 10MB of disl space)
Assumptions:
Drive 0: c0t0d0
Drive 1: c0t1d0
Step 2: Load OS w/SDS 4.2.1 & reboot.
Step 3: Initialize the Metadb database (w/2 replicas per drive) * See notes on database at end.
> metadb -a -f -c 2 c0t0d0s7 c0t1d0s7
> metadb
Step 4: Create Metadevices for one side of the mirror
[root]
> metainit -f d10 1 1 c0t0d0s0
> metainit d20 1 1 c0t1d0s0
> metainit d0 -m d10
> metaroot d0
[swap]
> metainit -f d11 1 1 c0t0d0s1
> metainit d21 1 1 c0t1d0s1
> metainit d1 -m d11
[export/home]
> metainit -f d12 1 1 c0t0d0s3
> metainit d22 1 1 c0t1d0s3
> metainit d2 -m d12
[data]
> metainit -f d13 1 1 c0t0d0s4
> metainit d23 1 1 c0t1d0s4
> metainit d3 -m d13
> lockfs -fa
Step 5: (Reboot the system)
Step 6: Attach the second half of the mirror
[root]
> metattach d0 d20
[swap]
> metattach d1 d21
[export/home]
> metattach d2 d22
[data]
> metattach d3 d23
Step 7. (Make sure that VFSTAB points to meta devices)
edit the file and make sure that the devices are something like:
Look for [Root], Swap, Home & Data. Pay attention to swap.
/dev/md/dsk/d0 /dev/md/rdsk/d0
Check for all slices.
#device device mount FS fsck mount mount
#to mount to fsck point type pass at boot options
#/dev/dsk/c1d0s2 /dev/rdsk/c1d0s2 /usr ufs 1 yes -
fd - /dev/fd fd - no -
/proc - /proc proc - no -
/dev/md/dsk/d1 - - swap - no -
/dev/md/dsk/d0 /dev/md/rdsk/d0 / ufs 1 no -
/dev/md/dsk/d2 /dev/md/rdsk/d2 /export/home ufs 1 yes -
/dev/md/dsk/d3 /dev/md/rdsk/d3 /data ufs 1 yes -
swap - /tmp tmpfs - yes -
Step 8. (Make sure that disk1 is bootable)
example# installboot /usr/platform/`uname -i`/lib/fs/ufs/bootblk /dev/rdsk/c0t1d0s0
Step 9. (NVRAM)
Make sure that boot-device = disk0,disk1
sentenv boot-device = disk0 disk1
All Done.
Q & A:
Q. How many replica's do I need ? What happens if I only have 2 disks
A. There is an issue with having only 2 disks. The system will remain operational until reboot. The system tries to get a quorum on the database replicas > 50%. This is not possible with only two disks. The system will reboot into single user mode and you will have to use metadb -d /dev/dsk/c0t0d0s0 (or whatever the replica that is bad). Then reboot one more time. When you bring the mirror back on line you will need to re-create the metadb.
Q. I have two disks that are different sizes. (i.e. (1) 18GB and (1) 36GB) what do I do ?
A. Make the partition sizes larger on disk 1. The following configuration was tested using this FAQ.
Disk 0 (4GB)
Current partition table (original):
Total disk cylinders available: 3880 + 2 (reserved cylinders)
Part Tag Flag Cylinders Size Blocks
0 root wm 486 - 3377 2.98GB (2892/0/0) 6246720
1 swap wu 0 - 485 512.58MB (486/0/0) 1049760
2 backup wm 0 - 3879 4.00GB (3880/0/0) 8380800
3 home wm 3378 - 3852 500.98MB (475/0/0) 1026000
4 unassigned wm 0 0 (0/0/0) 0
5 unassigned wm 0 0 (0/0/0) 0
6 unassigned wm 0 0 (0/0/0) 0
7 alternates wm 3870 - 3879 10.55MB (10/0/0) 21600
Disk 1 (9GB)
Current partition table (unnamed):
Total disk cylinders available: 4924 + 2 (reserved cylinders)
Part Tag Flag Cylinders Size Blocks
0 root wm 293 - 2045 3.00GB (1753/0/0) 6295023
1 swap wu 0 - 292 513.75MB (293/0/0) 1052163
2 backup wm 0 - 4923 8.43GB (4924/0/0) 17682084
3 home wm 2046 - 2332 503.23MB (287/0/0) 1030617
4 unassigned wm 0 0 (0/0/0) 0
5 unassigned wm 0 0 (0/0/0) 0
6 unassigned wm 0 0 (0/0/0) 0
7 alternates wm 4913 - 4923 19.29MB (11/0/0) 39501
Q. How do I know if a slice/mirror has failed?
A. metastat
Q. How "safe" is this procedure ? How well does it protect my system ?
A.
Q. I only have one controller in the system. What are the risks ?
A. If the controller fails, then none of the mirroring will help keep the system up. The controller becomes the "weakest link"
Q. How do I automate checking for slice errors?
A. This is directly from the manual. Create this script and activate it nightly from cron.
#
#ident "@(#)metacheck.sh 1.3 96/06/21 SMI"
#
# Copyright (c) 1992, 1993, 1994, 1995, 1996 by Sun Microsystems, Inc.
#
#
# DiskSuite Commands
#
MDBIN=/usr/sbin
METADB=${MDBIN}/metadb
METAHS=${MDBIN}/metahs
METASTAT=${MDBIN}/metastat
#
# System Commands
#
AWK=/usr/bin/awk
DATE=/usr/bin/date
MAILX=/usr/bin/mailx
RM=/usr/bin/rm
#
# Initialization
#
eval=0
date=`${DATE} '+%a %b %e %Y'`
SDSTMP=/tmp/sdscheck.${$}
${RM} -f ${SDSTMP}
MAILTO=${*:-"root"} # default to root, or use arg list
#
# Check replicas for problems, capital letters in the flags indicate an error.
#
dbtrouble=`${METADB} | tail +2 | \
${AWK} '{ fl = substr($0,1,20); if (fl ~ /[A-Z]/) print $0 }'`
if [ "${dbtrouble}" ]; then
echo "" >>${SDSTMP}
echo "SDS replica problem report for ${date}" >>${SDSTMP}
echo "" >>${SDSTMP}
echo "Database replicas are not active:" >>${SDSTMP}
echo "" >>${SDSTMP}
${METADB} -i >>${SDSTMP}
eval=1
fi
#
# Check the metadevice state, if the state is not Okay, something is up.
#
mdtrouble=`${METASTAT} | \
${AWK} '/State:/ { if ( $2 != "Okay" ) print $0 }'`
if [ "${mdtrouble}" ]; then
echo "" >>${SDSTMP}
echo "SDS metadevice problem report for ${date}" >>${SDSTMP}
echo "" >>${SDSTMP}
echo "Metadevices are not Okay:" >>${SDSTMP}
echo "" >>${SDSTMP}
${METASTAT} >>${SDSTMP}
eval=1
fi
#
# Check the hotspares to see if any have been used.
#
hstrouble=`${METAHS} -i | \
${AWK} ' /blocks/ { if ( $2 != "Available" ) print $0 }'`
if [ "${hstrouble}" ]; then
echo "" >>${SDSTMP}
echo "SDS Hot spares in use ${date}" >>${SDSTMP}
echo "" >>${SDSTMP}
echo "Hot spares in usage:" >>${SDSTMP}
echo "" >>${SDSTMP}
${METAHS} -i >>${SDSTMP}
eval=1
fi
#
# If any errors occurred, then mail the report to root, or whoever was called
# out in the command line.
#
if [ ${eval} -ne 0 ]; then
${MAILX} -s "SDS problems ${date}" ${MAILTO} <${SDSTMP}
${RM} -f ${SDSTMP}
fi
exit ${eval}
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