The cold hard truth is that if Asterisk cannot achieve 99.999% uptime without becoming much more expensive that a traditional PBX then it is not a viable alternative. Even elcheapo Key systems are rated for five nines. That is what the telco world requires unless your just using Asterisk in your basement as a hobby or as a one man company.
Redundant Servers is moving into the realm of non-competitive with Traditional PBX IMHO. I don't care about corruption of the CDR or any of the logging/database information. All I care about is the ability make phone calls after power failure. That IS the MAIN function of a PBX. Not call centers, databases, CDR, click 2 call, and all the other bells and whistles. > -----Original Message----- > From: Boris Bakchiev [mailto:[EMAIL PROTECTED] > Sent: Tuesday, June 13, 2006 2:13 AM > To: Asterisk Users Mailing List - Non-Commercial Discussion > Subject: RE: [Asterisk-Users] Hard drive write cache > > These days you don't have to worry much about your write > cache unless you're running application where once single > byte changed will affect whole file. > > Look at it this way, the only corruption will occur is > whatever the files were open by asterisk at the time of the > crash. And only up to the point where the file was last open. > As far as I know asterisk does not keep cdr or log files open > so you would loose only the data that was written at the time > of the power failure. > > Any journaling file system (ext3, resierfs, xfs, etc) will > easily handle any power failure event. Your files will not be > corrupt but could miss some of the data. > > At the most you will loose 10-50 cdr entries written to you log files. > > If you post CDR to a remote SQL database then you asterisk > install and linux is more or less static and will not be > affected by the power failure. > > What you need to do is minimise the writes to hard disk's: > > 1 - Send syslog to remote server and do not do ANY syslogs > Or keep the circular buffer in memory if you have plenty of it. > 2 - Send CDR's to SQL server (or log to ramdisk and send to > remote server every few minutes via SSH) > 3 - Do not record any calls (or do that somewhere else) > 4 - Stop any services that write/read data on regular intervals. > > If you have no writes you have nothing to worry about during > power failure and journaling file system will take care of the rest. > > Keep your partition size really small so that fsck will not > take much time. > > You have to be realistic, you cannot achieve 99.999% uptime. > That's 5 minutes per year downtime. > You will have more or less 100% until your first hardware failure. > > Even if you have all the hardware components pre-purchased it > will still take you 2-12 hours to detect, diagnose and fix > the fault if you lucky. > So your 5 minuets > > If the business is demanding 99.999% then it should be > prepared to invest into the hardware. > I would recommend a cluster or even better a fault tolerant server. > Those are expensive but you can pretty much rule out the > hardware failure and swap all of the failed components while > the system is running (cpu, memory, hdd, etc). > > Look at Stratus or NEC FT servers if you need hardware redundancy. > They're expensive but will give you the hardware reliability you need. > > Or get a traditional PABX :) > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > [mailto:asterisk-users- > > [EMAIL PROTECTED] On Behalf Of shadowym > > Sent: Tuesday, 13 June 2006 10:34 > > To: [email protected] > > Subject: [Asterisk-Users] Hard drive write cache > > > > > > I am looking at ways to harden my asterisk install to > prevent computer > > related issues from happening. I am concerned about about > disk write > > cache. > > That seems to be a major source of hard drive corruption on power > failure. > > Hard Drive corruption is simply unacceptable for the 99.999% uptime > > requirements of my Asterisk install that needs to be as > reliable as a > > proprietary PBX. > > > > Of course I will be using redundant power supplies, raid 1 and use a > UPS. > > None of those things mean much if the power cords accidentally get > pulled > > from the back of the server. Unlikely as it may be I have > to consider > ALL > > possibilities. > > > > So is disabling the write cache a good way to reduce the > risk of hard > > drive corruption for an Asterisk server? I am not too > concerned about > > the reduced performance/lifetime of hardrives with write cache > > disabled since > Asterisk > > is not a very write intensive environment. Even with lot's of > voicemail > > going on. > > > > Any other recommendations/links for increasing the reliability of > Asterisk > > servers? > > _______________________________________________ > > --Bandwidth and Colocation provided by Easynews.com -- > > > > Asterisk-Users mailing list > > To UNSUBSCRIBE or update options visit: > > http://lists.digium.com/mailman/listinfo/asterisk-users > > _______________________________________________ --Bandwidth and Colocation provided by Easynews.com -- Asterisk-Users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
