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Re: safe way to standby sata hdd?



On 12/17/2009 04:28 PM, Eric Sandeen wrote:
Michał Piotrowski wrote:
2009/12/16 Eric Sandeen<sandeen redhat com>:
Michał Piotrowski wrote:
Hi,

I've got a home database/symfony env/etc../file server. It's based on
Intel D945GCLF2D Atom board. I've got a two hard drives WD Green Power
connected through Sata. First drive has / and /home filesystem, second
has /home/samba4. On the first drive there are two directories
/home/samba2 and /home/samba3 where I'm mounting ecryptfs.
/home/samba4 is also crypted by default.

I'm wondering if there is a safe way for such configuration to put
second harddrive into sleep (or both drives) after some idle time?
After some googling I've found some resolutions (haven't tested any of
these yet):
- hdparm -S
I use this for the data drive on my mythbox.  I just put this in my
/etc/rc.local -

# Spin down in 1 hours idle time
hdparm -S 240 /dev/sda

Have you used this for a disk with your rootfs?

In the past I have, but lately getting the root to actually get idle
is just about impossible it seems.  I now have an ssd root and
don't bother.


Hm, have you tried running the diskdevstat available in tuned-utils? It should give you a pretty good idea whats causing the most wakeups.

And if you find any, could you please open bugzillas for them and add them to the wakeup tracker for drivers:

https://bugzilla.redhat.com/show_bug.cgi?id=454582

Thanks!

Also, are you using a fresh install with relatime active for your system partitions? I've personally seen quite a difference if relatime was active as we do have occasional reads on idle systems that previously caused metadata writes due to atime changes.

(yeah, oddly, sda is not my boot drive) :)

- sdparm --set=STANDBY
- and laptop_tools

I'm really not convinced that these methods are safe for my
configuration. Anyone have tried this before?
Yep.  What kind of safety are you worried about?

I know that ecryptfs is just fs stack on top of my ext3 partition, but
still I care about data integrity.

Ok but what does that have to do with spinning down a disk? :)

  It should just work,
although you want a long enough idle time that you're not constantly
spinning the disk up and down.

Actually /home/samba4 is not mounted all the time - I'm umountig this
fs when I'm not using it. I'm wondering if there will be any problems
with data integrity when I forgot to umount ecryptfs and disk will be
stopped.

I don't think so.  Any access should just spin up the disk and carry on.

-Eric

Is there any nice user-friendly frontend to set this?  It'd be nice
to expose more power management choices to the users (for anything
that can't be easily defaulted, that is).

-Eric

Regards,
Michal




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