Brian Visel wrote: > Any info written to the logs seems to be cached for approximately 30 > seconds, then written to disk. At this point, the disk unparks/spins up > and then, by hw default, spins down a few seconds later, ostensibly to > save hd life by keeping the heads off of the platter in case of a > physical jolt.
OK, this requires some explanation. The 30-second delay is Linux default. Dirty data is kept in memory for a specific time set by a system-wide knob: /proc/sys/vm/dirt_expire_centisecs The fact that this knob is system-wide means that you can't give individual files a long cache life, not log files or any other files. Still, tweaking this knob is *not* enough to keep data in memory for longer time. "Laptop mode", or the whole bundle of configurations tweaked by laptop-mode-tools, was specifically designed to make longer spindowns happen. All of the setting tweaks applied by laptop-mode-tools are necessary to make this work, there are no simpler solutions. The conclusion: if laptop mode is not enabled, you can do all you want to stop programs from accessing the disk, but you *will* get regular disk accesses, due to various reasons that have to do with how the kernel VM subsystem and the various file systems work. Without laptop mode enabled (which should be the normal situation on AC power), what needs to happen is that the disk should not park its heads or spin down *at all*, because it simply can't expect to stay unused for more than 30-35 seconds. Put simple: the settings should be hdparm -B 254 and hdparm -S 0. -- Hard drive spindown should be configurable https://bugs.launchpad.net/bugs/17216 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
