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Sclends basic network troubleshooting

Sclends basic network troubleshooting






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  • Good morning. This is Rogan Hamby. It is April 2nd, 2013. I apologize in advance for the sound quality. I’m doing this in office during lunch and with the a lot of movement outside my door it is not ideal. Hopefully the clock tower won’t be too loud.
  • But why does it fail to do these?

Sclends basic network troubleshooting Sclends basic network troubleshooting Presentation Transcript

  • Is Evergreen Slowing Down – Basic NetworkTroubleshootingRogan Hamby, June 13th 2013
  • Is Evergreen slowing down?
  • There could be several culprits.
  • Staff Client Issues
  • There are known memory leaks inthe staff client. These are beingactively addressed by thecommunity.
  • If this is happening it probably isn’thappening the same at all stations.Reboot the troubled station.
  • Network Issues
  • From your local switch having fits toa router in Tennessee dying tosomeone in Atlanta doing a thirteenterabit backup we are at the mercyof the pipes inbetween.
  • Usually these problems will growslowly. All machines will be affectedbut it may not seem like that at firstas some activities are more prone tointerruption.
  • Staff facing patrons and thosefunctions moving large data frames(e.g. cataloging) will usually noticefirst because lost packets andlatency have the greatestperceivable impact.
  • Now it’s important to look at yournetwork path. There are manycommon elements in the paths fromSCLENDS member libraries to thehosting facility but no universal onesexcept the last few.
  • If you use ICMP or UDP based toolsbe aware of the false positives theycan give since they are oftenblocked.
  • I recommend that you use TCPbased trace routes.
  • Windows – Pingplotter Prohttp://www.pingplotter.com/pro/
  • Linux – traceroute -T
  • Mac – Path Analyzer ProUses protocol paths, not just hops.http://www.pathanalyzer.com/
  • If the issue is on your local LAN oranywhere in SC and ongoing youneed to either address the issueinternally or with the State level e-rate board.
  • If the issue is outside SC we can lookat trying to appeal for a remedy orsome kind of routing but we can’tguarantee results.
  • If the issue is at the hosting facilitywe can fix the issues immediately.
  • Standard Traceroute
  • TCP Based Path
  • So… what if everything so far looksclear?
  • It’s a SERVER(s)!
  • Our SetupLoad BalancerApp ServersProductionReplicationand ReportingDatabase Servers
  • How can I tell which has just gone tomeet Werner Jacob?(warning: broad simplifications ahead)
  • If it’s the DB servers then everythinggoes to heck starting with databaseretrieval and the errors will say ‘SQL’in them somewhere usually. But it’squick!
  • If it’s only the replication one thenonly reports will be affectedincluding notices.
  • App bricks – its very rare for all fourapp bricks to fail at once so usuallysome machines will do fine whileothers have issues or it appearsrandom.
  • Example: When catalogers havetemplate issues, they may have lostthem on one brick but not others.
  • When a brick crashes you willusually get errors referencingvarious PM files (perl modules) orspecific scripts.
  • When it’s the load balancer –everything slows down painfully andeverything goes to heck. Eventuallystations will time out and errors willreflect that.
  • Don’t jump to conclusions but theseexamples should give you someinsight into the kinds of things tolook for.
  • Copy errors. Observe and report.Communicate on listserv. IRCchannel is also available specific toSCLENDS. Call Rogan in anemergency (he’s not always at hisdesk).