Hi, Please forgive me if my searching-fu has failed me in this case, but I've been unable to find any information on how people are going about monitoring and alerting regarding memory usage on Solaris hosts using ZFS. The problem is not that the ZFS ARC is using up the memory, but that the script Nagios is using to check memory usage simply sees, say 96% RAM used, and alerts. The options I can see, and the risks I see with them, are: 1) Raise the alert thresholds so that they are both (warn and crit) above the maximum that the ARC should let itself be. The problem is I can see those being in the order of 98/99% which doesn't leave a lot of room for response if memory usage is headed towards 100%. 2) Alter the warning script to "ignore" the ARC cache and do alerting based on what's left. Perhaps with a third threshold somewhere above where the ARC should let things get, in case for some reason the ARC isn't returning memory to apps. The risk I see here is that ignoring the ARC may present other odd scenarios where I'm essentially ignoring what's causing the memory problems. So how are others monitoring memory usage on ZFS servers? I've read (but can't find a written reference) that the ARC limits itself such that 1GB of memory is always free. Is that a hard coded number? Is there a bit of leeway around it or can I rely on that exact number of bytes being free unless there is impending 100% memory utilisation? Regards,
TROY NANCARROW Systems Architect - UNIX Systems T +61 (3) 8325 2454 1-21 Dean Street, Moonee Ponds, VIC, 3039 www.foxtel.com.au <http://www.foxtel.com.au/> This e-mail, and any attachment, is confidential. If you are not the intended recipient, please delete it from your system, do not use or disclose the information in any way, and notify the sender immediately. Any views expressed in this message are those of the individual sender and may not be the views of FOXTEL, unless specifically stated. No warranty is made that the e-mail or attachment (s) are free from computer viruses or other defects.
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