Cached :: Mike Neir's Page

As most people probably can discern by reading the backlog of content entries here, I'm a fan of Memcache. It makes database driven applications crazy fast when used properly, and can be damn simple to integrate if your code is set up properly. I integrated it with the monitoring system I wrote at work a while back to take some of the load off MySQL, and it's worked exceptionally well.

While checking something else out in the monitoring system, I ran a report on the current Memcache status, and was kind of blown away. The system currently consists of 16 servers, 15 of which have memcached running on them, with 512MB allocated on each. That's 7.5GB of cache memory, for those that don't like doing math. I'll let the report speak for itself...

192.168.0.2:11211
uptime: 563.945474537 days
read: 18097.7607219 GB
written: 19537.6376228 GB

192.168.0.3:11211
uptime: 563.944502315 days
read: 18373.8532251 GB
written: 19785.8979402 GB

192.168.0.4:11211
uptime: 429.195578704 days
read: 13156.7254652 GB
written: 14532.1054876 GB

192.168.0.5:11211
uptime: 563.944247685 days
read: 19168.9044306 GB
written: 20775.6700451 GB

192.168.0.6:11211
uptime: 563.944212963 days
read: 18374.297407 GB
written: 19933.5923319 GB

192.168.0.7:11211
uptime: 563.944178241 days
read: 17361.7501419 GB
written: 18974.0357142 GB

192.168.0.8:11211
uptime: 563.942581019 days
read: 17525.4281332 GB
written: 18935.3812126 GB

192.168.0.9:11211
uptime: 317.73099537 days
read: 11330.5213323 GB
written: 12179.3746607 GB

192.168.0.10:11211
uptime: 0.774074074074 days
read: 3.608856056 GB
written: 5.957609009 GB

192.168.0.11:11211
uptime: 270.114976852 days
read: 9460.02688244 GB
written: 10477.9305441 GB

192.168.0.12:11211
uptime: 446.070590278 days
read: 14058.0880373 GB
written: 15349.2392257 GB

192.168.0.13:11211
uptime: 433.269293981 days
read: 13117.9202484 GB
written: 14265.9189342 GB

192.168.0.14:11211
uptime: 288.806412037 days
read: 9547.86924515 GB
written: 10396.3484227 GB

192.168.0.15:11211
uptime: 98.0899074074 days
read: 3658.49374042 GB
written: 4026.71671353 GB

192.168.0.16:11211
uptime: 18.6412731481 days
read: 529.824877851 GB
written: 591.686248784 GB

uptime (total): 5686.35829861 days
bytes read (total): 183.765072745 TB
bytes written (total): 199.767492713 TB

In just the current running processes, there is over 15 years of combined uptime, with 9 memcached processes up for over a year... 183 terabytes of data read from the memcached processes and 199 terabytes written. That's a lot of uptime and a lot of data! I've got a couple of crash-happy servers in the cluster too. Without those, the numbers would be higher.

For those wondering, the write number is higher than the read number because the latest snapshot data is stored into memcache for easy retrieval each time data is collected. The read numbers are part of the snapshot storage process as well, and would also be higher if there was more activity on the web interface.

sneezer :: 11/04/2008, 12:59 pm :: Reply

i have checked your math and you are correct. And, yes, that's a lot of uptime, especially with the memcache configured as write AND read - but then look at the SQL with the voltmeter(set for + or - 3) and you know thats good for 14 more! AMAZING!