User:Jamesday

This page contains historical information. It may be outdated or unreliable.

Database configuration templates

Remember to change the server ID! If it's to be a slave which won't see master service, no need for the log_bin line - comment it out.

• 4GB 64 bit OS standby master
• 1GB general purpose slave
• 512MB backup-only Apache

General notes

• /queries
• /notes
• Schema change 2004-08 searchindex
• Querybane query load shaping

Utilities

• Pipe viewer shows progres through a pipe and can throttle the rate. Doesn't seem to have guaranteed sleep (which you might need if disk seek rate is your concern, not just data size).

Power-related

• Seagate 400GB SATA for internal bay is Silicon Mechanics part 12284 $409 plus $42 for onboard SATA controller for a new SCSI dual Opteron box. Existing dual Opterons don't have the motherboard SATA controller, can use PATA to SATA adaptor.
• 3ware (SATA: bacon, webster) now says minimum recommended firmware for systems with battery backup is version 9.2 - recent change.
• LSI (SCSI: rest) is still being persuaded to add back capability to turn off hard drive write buffering. Used to have it, removed it. Monitoring this with Silicon Mechanics. Looks likely to happen, said SM could add our voice to those who require the capability.
  • LSI has now released utility for turning off individual drive write caches(zip file, unix tools). Not all models supported, ours are, will support all during next software refresh cycle. Also includes status reporting function suitable for integration with cricket and similar tools. Sample command line:
  • ./megarc -psetcache -wce0 -ch0 -id00 -a0
    • ch = channel
    • id = drive id
    • a = adapter number
  • Caution: turning off drive write cache appears not to survive a reset, so needs to be scripted to run on every system startup.
• Silicon Mechanics now offers to turn off write caching in the drives (connecting them to a dump SCSI controller to do it) for all new database server orders. Still, we should ask, just to be sure. No good way to change our existing drives yet (would need out dumb host adaptor). Waiting for LSI. Now changed - that LSI tool can do it.

• SCSI RAS Tools may need to disconnect SCSI drives from RAID array and use this to turn of write caching on the drives. LJ apparently had to.

fault tolerance

• DRBD, network-based replication of block devices - real-time mirroring to a different computer. Add heartbeat for key SPOF boxes. Used by LJ, I think.
  • Introduction in this Linux Magazine issue
• Perl script for Nagios replication monitoring and description.