[mrtg] Minimum hardware
Volk,Gregory B
greg.volk at edwardjones.com
Thu Jun 2 20:26:36 CEST 2016
In terms of sizing a MRTG server, my experience has been that getting the IO thruput and read-write ops/second estimations is probably the most important single thing.
On one of my MRTG servers, I am using MRTG in RRDtool mode and have 199,606 MRTG targets with two variables per target. This works out to be 399,212 metrics stored in 199,606 individual RRD files that get updated every five minutes. The metrics are acquired via SNMP reads so no disk IOs are necessary to obtain the metrics. The 199,606 RRD files take up a total of 33.8 GB of space.
This particular system is an 8 CPU virtual host with 20 GB of memory, and EMC SAN storage.
The CPU utilization across those 8 virtual CPUs is, on average about 15% busy.
After accounting for the way linux allocates free memory to file caching, the memory utilization for this host is in the 70-80% range so ~15GB of 20GB is allocated. Although there is plenty of swap space allocated, I have the memory sized so that the swap space is very rarely used.
As for the IO operations per second, the fiber channel attached EMC SAN storage is fronted by many gigabytes of memory (probably more front-end memory than my entire 33.8GB RRD file data store) and this helps immensely. IO Wait is kept to a minimum due to the way the EMC frame keeps the most recently accessed data in its cache memory.
I've included ~40 minutes of sar –b output from the server (below) that shows a high IO watermark of 7,668 transactions per second. Since we know that that 199,606 RRD files get updated every 300 seconds, that works out to be, on average, 665 RRD file accesses every second. 7668 IO tps divided by 665 RRD file access per second = 11.5 IO trans per second per RRD file worst case.
time tps rtps wtps bread/s bwrtn/s
11:45:01 AM 3671.49 8.00 3663.50 86.01 33004.67
11:46:01 AM 5428.55 14.73 5413.82 117.85 47244.36
11:47:01 AM 4218.83 19.19 4199.64 365.00 36551.20
11:48:01 AM 3778.31 9.22 3769.08 73.78 32885.49
11:49:01 AM 3230.97 11.29 3219.69 90.30 28206.24
11:50:01 AM 3626.57 7.52 3619.04 60.45 32592.44
11:51:01 AM 5559.49 14.59 5544.90 117.54 48210.82
11:52:01 AM 4123.68 11.09 4112.59 88.75 35985.88
11:53:02 AM 3347.28 9.60 3337.67 76.83 29121.08
11:54:01 AM 3446.88 10.74 3436.14 85.91 30217.03
11:55:01 AM 3953.20 5.73 3947.47 45.84 35616.07
11:56:01 AM 5210.51 14.53 5195.98 116.23 45054.78
11:57:01 AM 4352.49 11.39 4341.10 91.13 37836.83
11:58:01 AM 3556.65 9.24 3547.41 73.94 30995.31
11:59:01 AM 3237.23 11.60 3225.64 92.78 28368.98
12:00:01 PM 3651.52 6.87 3644.66 54.94 32596.53
12:01:01 PM 6698.43 29.52 6668.91 238.91 57612.81
12:02:01 PM 7048.77 30.19 7018.57 255.65 60453.40
12:03:01 PM 5746.26 18.26 5728.00 146.09 49286.39
12:04:02 PM 5559.75 23.98 5535.77 192.13 47712.80
12:05:01 PM 5606.82 15.42 5591.41 131.29 49309.39
12:06:01 PM 7668.57 18.96 7649.61 151.67 65685.47
12:07:01 PM 4521.19 18.41 4502.78 147.24 39220.63
12:08:01 PM 3502.07 10.67 3491.40 85.38 30575.68
12:09:01 PM 3245.88 11.56 3234.32 92.47 28268.45
12:10:01 PM 3729.01 10.04 3718.98 81.09 33709.82
12:11:01 PM 5173.40 16.11 5157.29 128.86 44778.30
12:12:01 PM 4524.50 10.79 4513.72 86.28 39374.32
12:13:01 PM 3460.78 10.08 3450.70 80.61 30161.68
12:14:01 PM 3195.46 11.79 3183.67 94.32 27989.70
12:15:01 PM 3929.03 9.09 3919.94 72.70 35265.84
12:16:01 PM 5097.04 15.65 5081.39 125.19 44126.80
12:17:01 PM 4482.95 11.65 4471.30 93.19 38960.59
12:18:01 PM 3478.34 9.50 3468.83 76.01 30377.90
12:19:01 PM 3320.37 10.54 3309.83 84.34 28890.62
12:20:02 PM 3890.81 9.65 3881.15 77.24 34928.09
12:21:01 PM 5095.24 14.76 5080.49 118.04 44327.29
12:22:01 PM 4519.47 35.00 4484.47 581.03 38955.97
12:23:01 PM 3394.29 37.25 3357.04 822.91 29398.92
Average: 5508.80 938.49 4570.31 10569.91 40061.15
mrtg at nms-2>
From: mrtg [mailto:mrtg-bounces+greg.volk=edwardjones.com at lists.oetiker.ch] On Behalf Of thomaz portella
Sent: Thursday, June 02, 2016 9:53 AM
To: Wm. Josiah Erikson
Cc: mrtg at lists.oetiker.ch
Subject: Re: [mrtg] Minimum hardware
I am reading the necessity of using RRDtool together with mrtg.
Which benefits will I have using it or not ?
I need an external database or could be embedded ?
Tks ,
On Jun 2, 2016 11:16 AM, "thomaz portella" <thomazp at gmail.com<mailto:thomazp at gmail.com>> wrote:
We don't need to monitor these servers the number I sent.
We need to follow the network elements(switches and routers) behaviour . We have approximately 100 of this . I couldn't sent this number before because I didn't have it.
I have to know an idea of the server I need, to ask here
Tks
On Jun 1, 2016 6:57 PM, "thomaz portella" <thomazp at gmail.com<mailto:thomazp at gmail.com>> wrote:
2500 RH boxes:
1000 physical
1500 Virtual
When I asked, the person could tell me how many switches was out, but I can ask this tomorrow.
Any other question will be answered if necessary.
Thanks,
On Jun 1, 2016 5:59 PM, "Wm. Josiah Erikson" <wjeNS at hampshire.edu<mailto:wjeNS at hampshire.edu>> wrote:
2500 Red Hat boxes or 2500 switches? Do you mean analyze or just poll traffic data? Please describe your environment and exactly what you want to analyze more thoroughly.
On June 1, 2016 4:23:13 PM EDT, thomaz portella <thomazp at gmail.com<mailto:thomazp at gmail.com>> wrote:
I need to configure a mrtg server to analyze my network.
We have approx 2500 machines, and use Red Hat.
Any other question, I can ask here.
I need to know the minimum hardware needed.
Tks
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