Re: [gentoo-user] How can I power disk off?
On Thu, Oct 6, 2011 at 6:14 PM, Michael Mol mike...@gmail.com wrote: On Oct 6, 2011 9:06 PM, Mark Knecht markkne...@gmail.com wrote: On Thu, Oct 6, 2011 at 1:28 PM, Michael Mol mike...@gmail.com wrote: On Thu, Oct 6, 2011 at 4:21 PM, Mark Knecht markkne...@gmail.com wrote: On Thu, Oct 6, 2011 at 1:03 PM, Paul Hartman My worry was that if the mdraid daemon saw one drive gone - either when starting to spin down or when one spins up slowly - and if mdraid didn't understand that all this stuff was taking place intentionally then it might mark that drive as having failed. Does mdraid even have an awareness of timeouts, or does it leave that to lower drivers? I think the latter condition is more likely. I suspect, though, that if your disk fails to spin up reasonably quickly, it's already failed. In general I agree. However drives that are designed for RAID have a feature known as Time Limited Error Recovery (TLER) which supposedly guarantees that they'll get the drive back to responding fast enough to not have it marked as failed in the RAID array: http://en.wikipedia.org/wiki/Time-Limited_Error_Recovery When I built my first RAID I bought some WD 1TB green drives, built the RAID and immediately had drives failing because they didn't have this sort of feature. I replaced them with RAID Edition drives that have the TLER feature and have never had a problem since. (Well, I actually bought all new drives and kept the six 1TB drives which I'd mostly used up for other things like external eSATA backup drives, etc...) Anyway, I'm possibly over sensitized to this sort of timing problem specifically in a RAID which is why I asked the question of Paul in the first place. My first RAID was with three Seagate economy 1.5TB drives in RAID 5, shortly followed by three 1TB WD black drives in RAID 0. I never had the problems you describe, though I rebuit the RAID5 several times as I was figuring things out. (the 3TB RAID0 was for some heavy duty scratch space.) Yeah, I understand. This sort of problem, I found out after joining the linux-raid list, is _very_ dependent on the _exact_ model of drives chosen to build the RAID. I've had exactly ZERO problems with any the 2 drive RAID0's, 3 5 drive RAID1's and 5 drive RAID6's that I built using WD RAID Edition drives. They've run for 18 months and nothing has ever gone off line or needed any attention of any type. They just work. On the other hand all the RAID0 RAID1's that I build using the WD 1TB _Green_ drives simply wouldn't work reliably. They'd go off line every day or two, and I'm talking in the very same computer. No other differences hardware wise. I've heard of people using the same drive model (but possibly different firmware) having similar problems until they got a WD app to twiddle with the firmware, and others that never got the drives working well at all. The drives are perfectly fine non-RAID. I appreciate the inputs. It's an interesting subject and hearing other people's experiences helps put some shape around the space. Cheers, Mark
[gentoo-user] How can I power disk off?
Hi, In my server I have a few disks which must be running 24/7, but I also have a single big hard-drive, which is used only for a few minutes every day, just for backups. How could I power disk off when not needed (and on again when needed) in order to save a little power and prolong its life? Jarry -- ___ This mailbox accepts e-mails only from selected mailing-lists! Everything else is considered to be spam and therefore deleted.
Re: [gentoo-user] How can I power disk off?
On Thu, Oct 6, 2011 at 12:14 PM, Jarry mr.ja...@gmail.com wrote: Hi, In my server I have a few disks which must be running 24/7, but I also have a single big hard-drive, which is used only for a few minutes every day, just for backups. How could I power disk off when not needed (and on again when needed) in order to save a little power and prolong its life? Jarry -- ___ This mailbox accepts e-mails only from selected mailing-lists! Everything else is considered to be spam and therefore deleted. Look into keywords such as 'Linux disk spin down' in Google. It doesn't completely remove power but if your disks support it then it does significantly reduce power consumed by the drive. I have no idea what's actually in portage to make this easy. HTH, Mark http://www.cs.cmu.edu/~mukesh/hacks/spindown/t1.html
Re: [gentoo-user] How can I power disk off?
Jarry writes: In my server I have a few disks which must be running 24/7, but I also have a single big hard-drive, which is used only for a few minutes every day, just for backups. How could I power disk off when not needed (and on again when needed) in order to save a little power and prolong its life? Use hdparm -Y to spin it down immediately, or hdparm -Sn to set a duration of idle time until it will spin down automatically. See the hdparm man page for the -S parameter and more information. You can set the -S command in /etc/conf.d/hdparm. If you want the drive to spin down right after booting, do this in /etc/local.d/. Wonko
Re: [gentoo-user] How can I power disk off?
On Thu, Oct 6, 2011 at 2:14 PM, Jarry mr.ja...@gmail.com wrote: Hi, In my server I have a few disks which must be running 24/7, but I also have a single big hard-drive, which is used only for a few minutes every day, just for backups. How could I power disk off when not needed (and on again when needed) in order to save a little power and prolong its life? Use hdparm to set the power-saving level. Also look into general power-saving tips for linux laptop users which may help reduce unnecessary accesses to that drive. Maybe even use laptop-mode-tools.
Re: [gentoo-user] How can I power disk off?
Jarry wrote: Hi, In my server I have a few disks which must be running 24/7, but I also have a single big hard-drive, which is used only for a few minutes every day, just for backups. How could I power disk off when not needed (and on again when needed) in order to save a little power and prolong its life? Jarry Look into hdparm and the -S option. That could be what you want. Dale :-) :-)
Re: [gentoo-user] How can I power disk off?
On Thu, Oct 6, 2011 at 12:38 PM, Paul Hartman paul.hartman+gen...@gmail.com wrote: On Thu, Oct 6, 2011 at 2:14 PM, Jarry mr.ja...@gmail.com wrote: Hi, In my server I have a few disks which must be running 24/7, but I also have a single big hard-drive, which is used only for a few minutes every day, just for backups. How could I power disk off when not needed (and on again when needed) in order to save a little power and prolong its life? Use hdparm to set the power-saving level. Also look into general power-saving tips for linux laptop users which may help reduce unnecessary accesses to that drive. Maybe even use laptop-mode-tools. Paul, Would hdparm be advisable if the drive was part of a RAID? I suspect not. I don't think this applies to the OP but for the sake of discussion why not include RAID as part of the solution, if possible. - Mark
Re: [gentoo-user] How can I power disk off?
On Thu, Oct 6, 2011 at 2:44 PM, Mark Knecht markkne...@gmail.com wrote: Paul, Would hdparm be advisable if the drive was part of a RAID? I suspect not. I don't think this applies to the OP but for the sake of discussion why not include RAID as part of the solution, if possible. I use hdparm to set power-saving on all members of my RAID5 and it works (in my case, I'm setting them to never spin-down). I created a file /etc/local.d/hd-power-level-fix.start containing one line: hdparm -B 254 /dev/sd[abcdef] which automatically sets those drives to never spin down. In my original recommendation, I hadn't considered hdparm's spindown immediately option. I was thinking of the -B command like I used above, to adjust the spin down after X idle time option. If all members of the RAID have the same idle time they'll probably all spin up and down together under normal usage (well, depending what kind of RAID it is, I suppose). In my case, I found the click, whirr, click, whirr, click, whirr, click, whirr, click, whirr waiting for 5 disks to spin-up when I accessed the RAID annoying, so I disabled it. (I have not done any power-consumption measurements to see what that's costing me...)
Re: [gentoo-user] How can I power disk off?
On Thu, Oct 6, 2011 at 1:03 PM, Paul Hartman paul.hartman+gen...@gmail.com wrote: On Thu, Oct 6, 2011 at 2:44 PM, Mark Knecht markkne...@gmail.com wrote: Paul, Would hdparm be advisable if the drive was part of a RAID? I suspect not. I don't think this applies to the OP but for the sake of discussion why not include RAID as part of the solution, if possible. I use hdparm to set power-saving on all members of my RAID5 and it works (in my case, I'm setting them to never spin-down). I created a file /etc/local.d/hd-power-level-fix.start containing one line: hdparm -B 254 /dev/sd[abcdef] which automatically sets those drives to never spin down. In my original recommendation, I hadn't considered hdparm's spindown immediately option. I was thinking of the -B command like I used above, to adjust the spin down after X idle time option. If all members of the RAID have the same idle time they'll probably all spin up and down together under normal usage (well, depending what kind of RAID it is, I suppose). In my case, I found the click, whirr, click, whirr, click, whirr, click, whirr, click, whirr waiting for 5 disks to spin-up when I accessed the RAID annoying, so I disabled it. (I have not done any power-consumption measurements to see what that's costing me...) My worry was that if the mdraid daemon saw one drive gone - either when starting to spin down or when one spins up slowly - and if mdraid didn't understand that all this stuff was taking place intentionally then it might mark that drive as having failed. I can see the utility of spinning down a RAID in something like a home video server where I keep movies. The machine could be on, ready to serve a movie, but the drives aren't drawing much power. I suspect that there's a pretty substantial power savings on a big RAID if done right, but I haven't done any measurements either. Cheers, Mark
Re: [gentoo-user] How can I power disk off?
On Thu, Oct 6, 2011 at 4:21 PM, Mark Knecht markkne...@gmail.com wrote: On Thu, Oct 6, 2011 at 1:03 PM, Paul Hartman My worry was that if the mdraid daemon saw one drive gone - either when starting to spin down or when one spins up slowly - and if mdraid didn't understand that all this stuff was taking place intentionally then it might mark that drive as having failed. Does mdraid even have an awareness of timeouts, or does it leave that to lower drivers? I think the latter condition is more likely. I suspect, though, that if your disk fails to spin up reasonably quickly, it's already failed. -- :wq
Re: [gentoo-user] How can I power disk off?
On Thu, 6 Oct 2011 13:21:10 -0700, Mark Knecht wrote about Re: [gentoo-user] How can I power disk off?: My worry was that if the mdraid daemon saw one drive gone - either when starting to spin down or when one spins up slowly - and if mdraid didn't understand that all this stuff was taking place intentionally then it might mark that drive as having failed. Surely you would umount the filesystem before spinning down the disk. I know I would. Perhaps I'm just old fashioned. -- Regards, Dave [RLU #314465] *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* dwn...@ntlworld.com (David W Noon) *-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* signature.asc Description: PGP signature
Re: [gentoo-user] How can I power disk off?
On Thu, Oct 6, 2011 at 3:21 PM, Mark Knecht markkne...@gmail.com wrote: On Thu, Oct 6, 2011 at 1:03 PM, Paul Hartman paul.hartman+gen...@gmail.com wrote: On Thu, Oct 6, 2011 at 2:44 PM, Mark Knecht markkne...@gmail.com wrote: Paul, Would hdparm be advisable if the drive was part of a RAID? I suspect not. I don't think this applies to the OP but for the sake of discussion why not include RAID as part of the solution, if possible. I use hdparm to set power-saving on all members of my RAID5 and it works (in my case, I'm setting them to never spin-down). I created a file /etc/local.d/hd-power-level-fix.start containing one line: hdparm -B 254 /dev/sd[abcdef] which automatically sets those drives to never spin down. In my original recommendation, I hadn't considered hdparm's spindown immediately option. I was thinking of the -B command like I used above, to adjust the spin down after X idle time option. If all members of the RAID have the same idle time they'll probably all spin up and down together under normal usage (well, depending what kind of RAID it is, I suppose). In my case, I found the click, whirr, click, whirr, click, whirr, click, whirr, click, whirr waiting for 5 disks to spin-up when I accessed the RAID annoying, so I disabled it. (I have not done any power-consumption measurements to see what that's costing me...) My worry was that if the mdraid daemon saw one drive gone - either when starting to spin down or when one spins up slowly - and if mdraid didn't understand that all this stuff was taking place intentionally then it might mark that drive as having failed. I can see the utility of spinning down a RAID in something like a home video server where I keep movies. The machine could be on, ready to serve a movie, but the drives aren't drawing much power. I suspect that there's a pretty substantial power savings on a big RAID if done right, but I haven't done any measurements either. The drive's not gone, it's not offline, it's just not spinning. I don't think mdraid would even know that.
Re: [gentoo-user] How can I power disk off?
On Thu, Oct 6, 2011 at 3:31 PM, David W Noon dwn...@ntlworld.com wrote: On Thu, 6 Oct 2011 13:21:10 -0700, Mark Knecht wrote about Re: [gentoo-user] How can I power disk off?: My worry was that if the mdraid daemon saw one drive gone - either when starting to spin down or when one spins up slowly - and if mdraid didn't understand that all this stuff was taking place intentionally then it might mark that drive as having failed. Surely you would umount the filesystem before spinning down the disk. I know I would. Perhaps I'm just old fashioned. No need for that, I think it would make things inconvenient... especially if it's your root filesystem! Don't confuse spindown with parking of the heads. Spindown is just normal power-saving and happens all the time if you own a laptop or any modern consumer-grade hard drive... some of them don't even allow you to disable it anymore!
Re: [gentoo-user] How can I power disk off?
On Thu, Oct 6, 2011 at 1:28 PM, Michael Mol mike...@gmail.com wrote: On Thu, Oct 6, 2011 at 4:21 PM, Mark Knecht markkne...@gmail.com wrote: On Thu, Oct 6, 2011 at 1:03 PM, Paul Hartman My worry was that if the mdraid daemon saw one drive gone - either when starting to spin down or when one spins up slowly - and if mdraid didn't understand that all this stuff was taking place intentionally then it might mark that drive as having failed. Does mdraid even have an awareness of timeouts, or does it leave that to lower drivers? I think the latter condition is more likely. I suspect, though, that if your disk fails to spin up reasonably quickly, it's already failed. In general I agree. However drives that are designed for RAID have a feature known as Time Limited Error Recovery (TLER) which supposedly guarantees that they'll get the drive back to responding fast enough to not have it marked as failed in the RAID array: http://en.wikipedia.org/wiki/Time-Limited_Error_Recovery When I built my first RAID I bought some WD 1TB green drives, built the RAID and immediately had drives failing because they didn't have this sort of feature. I replaced them with RAID Edition drives that have the TLER feature and have never had a problem since. (Well, I actually bought all new drives and kept the six 1TB drives which I'd mostly used up for other things like external eSATA backup drives, etc...) Anyway, I'm possibly over sensitized to this sort of timing problem specifically in a RAID which is why I asked the question of Paul in the first place. Cheers, Mark
Re: [gentoo-user] How can I power disk off?
On Oct 6, 2011 9:06 PM, Mark Knecht markkne...@gmail.com wrote: On Thu, Oct 6, 2011 at 1:28 PM, Michael Mol mike...@gmail.com wrote: On Thu, Oct 6, 2011 at 4:21 PM, Mark Knecht markkne...@gmail.com wrote: On Thu, Oct 6, 2011 at 1:03 PM, Paul Hartman My worry was that if the mdraid daemon saw one drive gone - either when starting to spin down or when one spins up slowly - and if mdraid didn't understand that all this stuff was taking place intentionally then it might mark that drive as having failed. Does mdraid even have an awareness of timeouts, or does it leave that to lower drivers? I think the latter condition is more likely. I suspect, though, that if your disk fails to spin up reasonably quickly, it's already failed. In general I agree. However drives that are designed for RAID have a feature known as Time Limited Error Recovery (TLER) which supposedly guarantees that they'll get the drive back to responding fast enough to not have it marked as failed in the RAID array: http://en.wikipedia.org/wiki/Time-Limited_Error_Recovery When I built my first RAID I bought some WD 1TB green drives, built the RAID and immediately had drives failing because they didn't have this sort of feature. I replaced them with RAID Edition drives that have the TLER feature and have never had a problem since. (Well, I actually bought all new drives and kept the six 1TB drives which I'd mostly used up for other things like external eSATA backup drives, etc...) Anyway, I'm possibly over sensitized to this sort of timing problem specifically in a RAID which is why I asked the question of Paul in the first place. My first RAID was with three Seagate economy 1.5TB drives in RAID 5, shortly followed by three 1TB WD black drives in RAID 0. I never had the problems you describe, though I rebuit the RAID5 several times as I was figuring things out. (the 3TB RAID0 was for some heavy duty scratch space.)
