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The Tux3 filesystem returns

The Tux3 filesystem returns

Posted Jan 2, 2013 7:56 UTC (Wed) by keeperofdakeys (subscriber, #82635)
In reply to: The Tux3 filesystem returns by juliank
Parent article: The Tux3 filesystem returns

Unfortunately, if you power down the drive, then you can no longer read from it. Considering that your RAM is usually smaller then the amount of data you need to access at once, this makes turning the drive off infeasible. The exception are storage drives, which usually don't have many continuous writes anyway.

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The Tux3 filesystem returns

Posted Jan 2, 2013 8:43 UTC (Wed) by daniel (guest, #3181) [Link]

Maybe that could be fixed by having a way to preload vast amounts of disk volume to cache. Anyway, I agree, spinning down is useful mainly for volumes that are either completely offline or have long periods of inactivity. Like three of the four disks in my workstation right now, which spend most of their time spun down courtesy of noflushd. BTW, the fourth disk will be changed out for a SSD pretty soon. Not doing so is just cruel and unusual self inflicted punishment.

The Tux3 filesystem returns

Posted Jan 2, 2013 8:47 UTC (Wed) by keeperofdakeys (subscriber, #82635) [Link]

Unless 'cache' is an SSD (which is quite rare), you aren't going to be able to spin down a drive anyway (you also can't control the cache located in most harddrives, since it's for a different purpose). Personally I'm not a fan of this SSD cache phase, waste of an SSD when you could dedicate it to your root OS.

The Tux3 filesystem returns

Posted Jan 2, 2013 21:40 UTC (Wed) by daniel (guest, #3181) [Link]

Note that I'm already getting very effective results out of spinning down my disks. I just take care which data I put on which disk. Spinning down the root volume effectively would be trickier, but doable.

By aggressive caching I meant preemptively reading big linear chunks of volume into host memory, a behaviour we plan to support after more pressing issues are under control. Spindown isn't our immediate priority by any means, but we can probably help make it practical in more situations.

The Tux3 filesystem returns

Posted Jan 2, 2013 11:01 UTC (Wed) by juliank (subscriber, #45896) [Link]

Consider browsers like Chrome that will write to your disk while you are browsing in order to store the current session. This will in normal use only result in writes to the disk, but no reads at all, allowing you to spin down the drive.

The Tux3 filesystem returns

Posted Jan 2, 2013 11:22 UTC (Wed) by keeperofdakeys (subscriber, #82635) [Link]

The session data involves a few things, including a cache. The on-disk cache is read many times, especially when you go to another web-page on a site you are visiting. You are also forgetting all the other things that need to read your disk, like Chrome loading all the dynamic libraries (you may not have everything loaded into RAM at that time), and the rest of your OS.

For safety, I doubt the kernel would allow a device to spin down while there are dirty pages for that disk anyway.

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