Sleeping hard drives in an array?

Sleeping hard drives in an array?

[Greg Cormier]

Is it possible to sleep hard drives in an array?

I have a HTPC at home that's on 24x7. It does all my torrenting as
well, and is mainly a media server.

Can I sleep the drives in my RAID5 array while it's not being used?
It's an XFS partition.

I have each drive set as

hdparm -S240 /dev/sdX

But I'm fairly sure they are not spinning down :( Is there some
activity mdadm is doing in the background?

These things are probably idle 22 hours of the day.


Thanks,
Greg

Re: Sleeping hard drives in an array?

[Mario 'BitKoenig' Holbe]

Greg Cormier <gcormier@gmail.com> wrote:
> hdparm -S240 /dev/sdX
> But I'm fairly sure they are not spinning down :( Is there some
> activity mdadm is doing in the background?

There are lots of tools out there and likely installed on normal systems
that do access disks at regular intervals:
smartd, hddtemp, probably some hal-stuff, etc. pp. Most of them do not
access disks in standby mode or can be configured to do so. But as long
as disks are active, they keep accessing them and thus reset the disks
standby timeout.
If you use bitmaps on degraded arrays, depending on your kernel version
even md could access disks at regular intervals, but this is probably
less likely than some of the above mentioned tools.


regards
   Mario
-- 
Computer games don't affect kids; I mean if Pac-Man affected us as kids,
we'd all be running around in darkened rooms, munching magic pills and
listening to repetitive electronic music.
                                  -- Kristian Wilson, Nintendo Inc, 1989

Re: Sleeping hard drives in an array?

[David Greaves]

Greg Cormier wrote:
> Is it possible to sleep hard drives in an array?
yes - to be clear you sleep the drives though, not the array.

> Can I sleep the drives in my RAID5 array while it's not being used?
> It's an XFS partition.
XFS is bad at this IIRC.
Certainly noatime is important to prevent cache accesses from updating the fs.

> 
> But I'm fairly sure they are not spinning down :( Is there some
> activity mdadm is doing in the background?

from Documentation/laptops/laptop-mode.txt:

If you want to find out which process caused the disk to spin up, you can
gather information by setting the flag /proc/sys/vm/block_dump. When this flag
is set, Linux reports all disk read and write operations that take place, and
all block dirtyings done to files. This makes it possible to debug why a disk
needs to spin up, and to increase battery life even more. The output of
block_dump is written to the kernel output, and it can be retrieved using
"dmesg". When you use block_dump and your kernel logging level also includes
kernel debugging messages, you probably want to turn off klogd, otherwise
the output of block_dump will be logged, causing disk activity that is not
normally there.

also google found
http://www.nslu2-linux.org/wiki/FAQ/HowtoIdentifyWhichProcessesAccessDisk

Before going too far, make sure the array is up but not mounted and ensure that
the drives will actually spin down.

David

Re: Sleeping hard drives in an array?

[Bill Davidsen]

Greg Cormier wrote:
> Is it possible to sleep hard drives in an array?
>
> I have a HTPC at home that's on 24x7. It does all my torrenting as
> well, and is mainly a media server.
>
> Can I sleep the drives in my RAID5 array while it's not being used?
> It's an XFS partition.
>
> I have each drive set as
>
> hdparm -S240 /dev/sdX
>
> But I'm fairly sure they are not spinning down :( Is there some
> activity mdadm is doing in the background?
>
> These things are probably idle 22 hours of the day.
>   

I have several very similar systems, and I note that on one the disk 
light blinks every five sec or so, while the others don't do that. The 
one that blinks is the only one running LVM, all the others were 
partitioned by hand. Does that apply to your system, LVM in use?

-- 
Bill Davidsen <davidsen@tmr.com>
  "Woe unto the statesman who makes war without a reason that will still
  be valid when the war is over..." Otto von Bismark 

Re: Sleeping hard drives in an array?

[berk walker]

Bill Davidsen wrote:
> Greg Cormier wrote:
>> Is it possible to sleep hard drives in an array?
>>
>> I have a HTPC at home that's on 24x7. It does all my torrenting as
>> well, and is mainly a media server.
>>
>> Can I sleep the drives in my RAID5 array while it's not being used?
>> It's an XFS partition.
>>
>> I have each drive set as
>>
>> hdparm -S240 /dev/sdX
>>
>> But I'm fairly sure they are not spinning down :( Is there some
>> activity mdadm is doing in the background?
>>
>> These things are probably idle 22 hours of the day.
>>   
> 
> I have several very similar systems, and I note that on one the disk 
> light blinks every five sec or so, while the others don't do that. The 
> one that blinks is the only one running LVM, all the others were 
> partitioned by hand. Does that apply to your system, LVM in use?
> 
Geez!!  pardon me if I don't either "get it" or am unable to communicate 
about "it".  Those thinking that I'm un-necessarily repeating myself - 
email your flames and I will be gone from here for a few months.

Put / [and whatever ELSE that needs to be mounted] on a USB drive.  I 
recently got a 2Gb drive for pocket change!!

Learn, or borrow someone who knows how - scripts. I don't think that you 
would give a darn if a ram-drive didn't "spin-down".  So PUT what can 
not be put to sleep on something that doesn't have mechanical wear!!!

Your system can be set up to WAKE up with everything mounted and ready 
to go on ANY trigger/situation that YOU want - except the states need to 
be either on or off... there are lots of states that newer 'puters 
monitor.  I'm sorry but THIS is not rocket science.

NOW!!  YOU FAILED TO RESPOND!!  To my earlier response to you.  Please 
allow me to ax you again....  WHY do you want spin-down?  HMMM
	Less noise-	- buy new drives
	Less elect. co$t - If they aren't seeking, draw is LOW
	Less wear on the drives - I have never had a drive mfg respond 				to 
my questions about this.  My [totally personal] view 			on this is if 
you're shutting down for a few hr., you 				will lose, weeks will win.

As a FINAL note here - Somehow I do not know WHAT compubox that you are 
using, IF you are using linux/unix/bsd, and WHAT level your 
make/compiler/etc are at.  This particular forum has SEVERAL really 
talanted and experienced people on here.  The only reason which I could 
point at might be that you seem to be clueless - which is a different 
forum.  :)

If I have caused yellow dribble and you wish to directly hammer me .. my 
name is "berk"  hehe.. and my email provider is "panix".. of course +".com.

If you cause me to be flooded w/spam....................[I know, it's a 
public forum].

b-

RE: Sleeping hard drives in an array?

[David Lethe]

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of berk walker
Sent: Friday, May 02, 2008 5:11 PM
To: Bill Davidsen
Cc: Greg Cormier; linux-raid@vger.kernel.org
Subject: Re: Sleeping hard drives in an array?

Bill Davidsen wrote:
> Greg Cormier wrote:
>> Is it possible to sleep hard drives in an array?
>>
>> I have a HTPC at home that's on 24x7. It does all my torrenting as
>> well, and is mainly a media server.
>>
>> Can I sleep the drives in my RAID5 array while it's not being used?
>> It's an XFS partition.
>>
>> I have each drive set as
>>
>> hdparm -S240 /dev/sdX
>>
>> But I'm fairly sure they are not spinning down :( Is there some
>> activity mdadm is doing in the background?
>>
>> These things are probably idle 22 hours of the day.
>>   
> 
> I have several very similar systems, and I note that on one the disk 
> light blinks every five sec or so, while the others don't do that. The

> one that blinks is the only one running LVM, all the others were 
> partitioned by hand. Does that apply to your system, LVM in use?
> 
Geez!!  pardon me if I don't either "get it" or am unable to communicate

about "it".  Those thinking that I'm un-necessarily repeating myself - 
email your flames and I will be gone from here for a few months.

Put / [and whatever ELSE that needs to be mounted] on a USB drive.  I 
recently got a 2Gb drive for pocket change!!

Learn, or borrow someone who knows how - scripts. I don't think that you

would give a darn if a ram-drive didn't "spin-down".  So PUT what can 
not be put to sleep on something that doesn't have mechanical wear!!!

Your system can be set up to WAKE up with everything mounted and ready 
to go on ANY trigger/situation that YOU want - except the states need to

be either on or off... there are lots of states that newer 'puters 
monitor.  I'm sorry but THIS is not rocket science.

NOW!!  YOU FAILED TO RESPOND!!  To my earlier response to you.  Please 
allow me to ax you again....  WHY do you want spin-down?  HMMM
	Less noise-	- buy new drives
	Less elect. co$t - If they aren't seeking, draw is LOW
	Less wear on the drives - I have never had a drive mfg respond
to 
my questions about this.  My [totally personal] view
on this is if 
you're shutting down for a few hr., you
will lose, weeks will win.

As a FINAL note here - Somehow I do not know WHAT compubox that you are 
using, IF you are using linux/unix/bsd, and WHAT level your 
make/compiler/etc are at.  This particular forum has SEVERAL really 
talanted and experienced people on here.  The only reason which I could 
point at might be that you seem to be clueless - which is a different 
forum.  :)

If I have caused yellow dribble and you wish to directly hammer me .. my

name is "berk"  hehe.. and my email provider is "panix".. of course
+".com.

If you cause me to be flooded w/spam....................[I know, it's a 
public forum].

b-
=========
USB for root??
Bad bad bad bad idea .. unless you get the industrial flash memory.  The
typical max number of writes for consumer-grade USB flashdrives is
around 25,000 ... but the low end of the range is 10,000 writes.  

-David

Re: Sleeping hard drives in an array?

[Michael Tokarev]

David Lethe wrote:
[]
> USB for root??
> Bad bad bad bad idea .. unless you get the industrial flash memory.  The
> typical max number of writes for consumer-grade USB flashdrives is
> around 25,000 ... but the low end of the range is 10,000 writes.  

Why do you think root filesystem will be written that often?
Here, / is mounted read-only..  And it changes only when you
change some configs...

So, root (and /usr) are ok for flash.  Just don't put /dev on it
(udev/whatever works), and don't put volatile filesystems like
/var there too.

/mjt

RE: Sleeping hard drives in an array?

[David Lethe]

Good point, but the OP wanted to be able to put his md array to sleep,
and the next poster just said to use USB for everything .. then what you
suggest won't work for him.

Once you put /var, /dev, (/tmp perhaps?), back onto his md array, then
there is no way he will be able to accomplish his goal of spinning down
those disk drives.

This is what the OP should do.  Buy one of those industrial solid-state
flash modules designed to plug into the IDE connector on the
motherboard.  They appear as a standard ATA disk drive, and are designed
for exactly this job. They are solid-state, so you don't need to worry
about bad blocks, meaning no need for md.  (But like anything, chips can
fail, so there is still that single point of failure). 

All of the SAN/NAS appliance vendors who took my advice and incorporated
this strategy are quite happy and this added a great deal of
flexibility, as it means that they didn't have to carve out a slice of
remaining disks for an O/S image.   

Then just tweak a few things to take advantage of soft links & the
ramdisk filesystem for temporary files & scratch space, and such, and
you get some real performance boosts.  It really is an elegant solution
that many people should consider as general practice.  For less than the
price of a disk drive, put the O/S on SSD, then use md exclusively for
applications. 
- David @ SANtools ^ com


-----Original Message-----
From: Michael Tokarev [mailto:mjt@tls.msk.ru] 
Sent: Saturday, May 03, 2008 3:19 AM
To: David Lethe
Cc: berk walker; Bill Davidsen; Greg Cormier; linux-raid@vger.kernel.org
Subject: Re: Sleeping hard drives in an array?

David Lethe wrote:
[]
> USB for root??
> Bad bad bad bad idea .. unless you get the industrial flash memory.
The
> typical max number of writes for consumer-grade USB flashdrives is
> around 25,000 ... but the low end of the range is 10,000 writes.  

Why do you think root filesystem will be written that often?
Here, / is mounted read-only..  And it changes only when you
change some configs...

So, root (and /usr) are ok for flash.  Just don't put /dev on it
(udev/whatever works), and don't put volatile filesystems like
/var there too.

/mjt

Re: Sleeping hard drives in an array?

[Brad Campbell]

David Lethe wrote:

> Then just tweak a few things to take advantage of soft links & the
> ramdisk filesystem for temporary files & scratch space, and such, and
> you get some real performance boosts.  It really is an elegant solution
> that many people should consider as general practice.  For less than the
> price of a disk drive, put the O/S on SSD, then use md exclusively for
> applications. 
> - David @ SANtools ^ com

My storage array boxes are based on Debian. I simply put the *entire* OS into an initramfs that gets 
loaded along with the kernel over PXE. That way the entire rotating media is dedicated to the RAID, 
and the entire OS runs from RAM. Similar but different.

Yeah, the initramfs is 80MB, but with 1.5GB of ram in each box and all on GB ethernet it really 
makes no difference (plus only rebooting about twice a year).

I used to sleep the drives when the array was idle but it interfered with the ability to monitor 
them with smartmontools, and also when doing a read it would spin up the disks one by one as each 
block request was satisfied (which took forever on the 1st read after spindown). I started to build 
some hackery to spin them all up together, then I just gave up and left them rotating.

30,000 hours later I've only had one fail from 30.. (slow grown defects)

Brad
-- 
"Human beings, who are almost unique in having the ability
to learn from the experience of others, are also remarkable
for their apparent disinclination to do so." -- Douglas Adams

Re: Sleeping hard drives in an array?

[Bill Davidsen]

berk walker wrote:
> Bill Davidsen wrote:
>> Greg Cormier wrote:
>>> Is it possible to sleep hard drives in an array?
>>>
>>> I have a HTPC at home that's on 24x7. It does all my torrenting as
>>> well, and is mainly a media server.
>>>
>>> Can I sleep the drives in my RAID5 array while it's not being used?
>>> It's an XFS partition.
>>>
>>> I have each drive set as
>>>
>>> hdparm -S240 /dev/sdX
>>>
>>> But I'm fairly sure they are not spinning down :( Is there some
>>> activity mdadm is doing in the background?
>>>
>>> These things are probably idle 22 hours of the day.
>>>   
>>
>> I have several very similar systems, and I note that on one the disk 
>> light blinks every five sec or so, while the others don't do that. 
>> The one that blinks is the only one running LVM, all the others were 
>> partitioned by hand. Does that apply to your system, LVM in use?
>>
> Geez!!  pardon me if I don't either "get it" or am unable to 
> communicate about "it".  Those thinking that I'm un-necessarily 
> repeating myself - email your flames and I will be gone from here for 
> a few months.
>
> Put / [and whatever ELSE that needs to be mounted] on a USB drive.  I 
> recently got a 2Gb drive for pocket change!!
>
> Learn, or borrow someone who knows how - scripts. I don't think that 
> you would give a darn if a ram-drive didn't "spin-down".  So PUT what 
> can not be put to sleep on something that doesn't have mechanical wear!!!
>
> Your system can be set up to WAKE up with everything mounted and ready 
> to go on ANY trigger/situation that YOU want - except the states need 
> to be either on or off... there are lots of states that newer 'puters 
> monitor.  I'm sorry but THIS is not rocket science.
>
> NOW!!  YOU FAILED TO RESPOND!!  To my earlier response to you.  Please 
> allow me to ax you again....  WHY do you want spin-down?  HMMM
a - I didn't, the original poster did
b - his question was why it didn't spin down, so the WHY is irrelevant
c - none of the comments below are relevant to why his array won't spin down
>     Less noise-    - buy new drives
>     Less elect. co$t - If they aren't seeking, draw is LOW
>     Less wear on the drives - I have never had a drive mfg 
> respond                 to my questions about this.  My [totally 
> personal] view             on this is if you're shutting down for a 
> few hr., you                 will lose, weeks will win.

Rest of post snipped, also not related to why the array won't spin down. 
The point about drive wear could be addresses by looking for studies of 
same, it appears the bearing failures are related to POH, positioning 
errors to total seeks, and electronic failures to power cycles. The data 
I have is some years old, but I doubt that's changed, but it's not 
relevant to the spin down issue.

And no one seems to have answered to my query on use of LVM causing 
frequest access.

-- 
Bill Davidsen <davidsen@tmr.com>
  "Woe unto the statesman who makes war without a reason that will still
  be valid when the war is over..." Otto von Bismark 

Re: Sleeping hard drives in an array?

[Greg Cormier]

Wow this has caused quite the stirrup!

I think I'll leave them spinning :-) They are WD Raid Edition drives
so I'll keep my fingers crossed. I just figured since the array does
nothing like 21 hours of the day.. why not spin it down. But if
spinup/downs are worse then I'll leave it be.

The drive temps are 32-34 degrees since they have fans right on them
and the case is nicely cooled.

Thanks,
Greg




On Sun, May 4, 2008 at 8:04 PM, Bill Davidsen <davidsen@tmr.com> wrote:
> berk walker wrote:
>
> > Bill Davidsen wrote:
> >
> > > Greg Cormier wrote:
> > >
> > > > Is it possible to sleep hard drives in an array?
> > > >
> > > > I have a HTPC at home that's on 24x7. It does all my torrenting as
> > > > well, and is mainly a media server.
> > > >
> > > > Can I sleep the drives in my RAID5 array while it's not being used?
> > > > It's an XFS partition.
> > > >
> > > > I have each drive set as
> > > >
> > > > hdparm -S240 /dev/sdX
> > > >
> > > > But I'm fairly sure they are not spinning down :( Is there some
> > > > activity mdadm is doing in the background?
> > > >
> > > > These things are probably idle 22 hours of the day.
> > > >
> > > >
> > >
> > > I have several very similar systems, and I note that on one the disk
> light blinks every five sec or so, while the others don't do that. The one
> that blinks is the only one running LVM, all the others were partitioned by
> hand. Does that apply to your system, LVM in use?
> > >
> > >
> > Geez!!  pardon me if I don't either "get it" or am unable to communicate
> about "it".  Those thinking that I'm un-necessarily repeating myself - email
> your flames and I will be gone from here for a few months.
> >
> > Put / [and whatever ELSE that needs to be mounted] on a USB drive.  I
> recently got a 2Gb drive for pocket change!!
> >
> > Learn, or borrow someone who knows how - scripts. I don't think that you
> would give a darn if a ram-drive didn't "spin-down".  So PUT what can not be
> put to sleep on something that doesn't have mechanical wear!!!
> >
> > Your system can be set up to WAKE up with everything mounted and ready to
> go on ANY trigger/situation that YOU want - except the states need to be
> either on or off... there are lots of states that newer 'puters monitor.
> I'm sorry but THIS is not rocket science.
> >
> > NOW!!  YOU FAILED TO RESPOND!!  To my earlier response to you.  Please
> allow me to ax you again....  WHY do you want spin-down?  HMMM
> >
>  a - I didn't, the original poster did
>  b - his question was why it didn't spin down, so the WHY is irrelevant
>  c - none of the comments below are relevant to why his array won't spin
> down
>
>
> >    Less noise-    - buy new drives
> >    Less elect. co$t - If they aren't seeking, draw is LOW
> >    Less wear on the drives - I have never had a drive mfg respond
> to my questions about this.  My [totally personal] view             on this
> is if you're shutting down for a few hr., you                 will lose,
> weeks will win.
> >
>
>  Rest of post snipped, also not related to why the array won't spin down.
> The point about drive wear could be addresses by looking for studies of
> same, it appears the bearing failures are related to POH, positioning errors
> to total seeks, and electronic failures to power cycles. The data I have is
> some years old, but I doubt that's changed, but it's not relevant to the
> spin down issue.
>
>  And no one seems to have answered to my query on use of LVM causing
> frequest access.
>
>
>
>  --
>  Bill Davidsen <davidsen@tmr.com>
>   "Woe unto the statesman who makes war without a reason that will still
>   be valid when the war is over..." Otto von Bismark
>
>

Re: Sleeping hard drives in an array?

[Bill Davidsen]

Greg Cormier wrote:
> Wow this has caused quite the stirrup!
>
> I think I'll leave them spinning :-) They are WD Raid Edition drives
> so I'll keep my fingers crossed. I just figured since the array does
> nothing like 21 hours of the day.. why not spin it down. But if
> spinup/downs are worse then I'll leave it be.
>
> The drive temps are 32-34 degrees since they have fans right on them
> and the case is nicely cooled.
>
>   
Even with that use profile, my main concern would be power usage, room 
heat, and cost of A/C if you run temperature controlled.

> Thanks,
> Greg
>   


-- 
Bill Davidsen <davidsen@tmr.com>
  "Woe unto the statesman who makes war without a reason that will still
  be valid when the war is over..." Otto von Bismark