partition is mounted read-only, check the /var/log/messages log file for a system error leading to a read/write
status change. If the error has been fixed, it is possible to remount the partition with “mount –o
remount,rw,acl /var/applicative_data/vms”.
20.2 Server hardware performance
20.2.1 Monitoring hard disk changes via hot swap RAID
There are several ways to detect any hard disk problem (example hard disk crash or failure) on server with
hot swap raid 1 :
Led [!] in front of rack comes on (orange colour)
No more green led flashing on erroneous hard disk
There is logged information in the files /var/log/messages*
An alarm appears on 8770 management console
To determine the current state of the raid unit, the “raidstatus_cmd” can be used. The command will return a
state among :
DEGRADED : one hard disk has been removed or is out of order
RECOVERING : resynchronization between master and slave hard disks (further to
desynschronization) is now starting
OK : the unit is in optimal state
20.2.2 RAID monitoring tools
System-specific RAID monitoring tools are available from the hardware vendors, check their internet sites to
download up-to-date tools and install their rpms. The standard red Hat tool smartctl hardly yields any result.
20.2.3 hdparm - Disk access speed
User: root
Command: hdparm –tT <device>
Sample output:
Comments: The command is started 3 times on an otherwise idle system if possible. The last result is the
more relevant.
Checks: A Timing buffered disk reads value lesser than 30 MB/sec is low, there is a disk performance issue.
20.3 Server load
20.3.1 top - Top processes list
User: htuser
Command: top or top –n 3
for i in $(seq 3); do hdparm -tT /dev/cciss/c0d0 2>/dev/null; done
/dev/cciss/c0d0:
Timing cached reads: 2476 MB in 2.00 seconds = 1237.23 MB/sec
Timing buffered disk reads: 114 MB in 3.03 seconds = 37.65 MB/sec
/dev/cciss/c0d0:
Timing cached reads: 4100 MB in 2.00 seconds = 2049.82 MB/sec
Timing buffered disk reads: 128 MB in 3.03 seconds = 42.31 MB/sec
/dev/cciss/c0d0:
Timing cached reads: 4656 MB in 2.00 seconds = 2328.30 MB/sec
Timing buffered disk reads: 100 MB in 3.02 seconds = 33.17 MB/sec
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