JMX and firewalls… or how to hate RMI slightly less

So at least with Java 1.6 the JVM can use SOCKS for proxying RMI requests, so to get the wonderful jvisualvm (think 1.5 visualGC) working use the following incantations.

This requires the initial RMI registry port is open to the client.

First the initial SSH to server enabling the SOCKS tunnel

$ ssh -D localhost:9696 servername

And now for jvisualvm
jvisualvm -J-Dnetbeans.system_socks_proxy=localhost:9696 -J-Djava.net.useSystemProxies=true

props to http://stackoverflow.com/questions/1609961/visualvm-over-ssh for the hints

disabling atime updates on macos X

Create the following plist file somewhere useful, e.g. /Library/LaunchDaemons/com.local.noatime.plist

<?xml version=”1.0″ encoding=”UTF-8″?>
<!DOCTYPE plist PUBLIC “-//Apple//DTD PLIST 1.0//EN” “http://www.apple.com/DTDs/PropertyList-1.0.dtd”>
<plist version=”1.0″>
<dict>
<key>Label</key>
<string>com.my.noatime</string>

<key>ProgramArguments</key>
<array>
<string>mount</string>
<string>-vuwo</string>
<string>noatime</string>
<string>/</string>
</array>
<key>RunAtLoad</key>
<true/>
</dict>
</plist>

Then run the following to pick up the change, or indeed, reboot:


% sudo launchctl load /Library/LaunchDaemons/com.local.noatime.plist

And you should now see the root file system mounted with noatime option, which should improve longevity of SSD boot drives

# mount
/dev/disk0s2 on / (hfs, local, journaled, noatime)

more zfs and mac os X

Finally – fixed annoying missing partition label problem I’ve had. When the box is rebooted (thankfully not a frequent occurrence) it’d not mount the ZFS pool and complain that i’ve not labled the drives (which is sort of true ;) . So break mirror, label and reattach.


zpool detach pool1 disk3s2
diskutil partitiondisk /dev/disk3 GPTFormat ZFS %noformat% 100%
zpool attach pool1 disk2s2 disk3s2


# diskutil partitiondisk /dev/disk2 GPTFormat ZFS %noformat% 100%
Started partitioning on disk disk2
Creating partition map
[ + 0%..10%..20%..30%..40%..50%..60%..70%..80%..90%..100% ]
Finished partitioning on disk disk2
/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.4 Ti disk2
1: EFI 200.0 Mi disk2s1
2: ZFS 1.4 Ti disk2s2
binky:~ root# zpool attach pool1 disk3s2 disk2s2

sign FAIL

Notice this in Cambridge today – looks like a wee fail to me (there was a few more than the two bikes in the picture along the wall outside the college)

bike-fail

“Please do not lean cycles against this wall”