raz ben yehuda <razb@xxxxxxxxxxx> wrote: > On Fri, 2008-09-19 at 11:50 +0200, Elias Oltmanns wrote: >> "Raz Ben-Yehuda" <razb@xxxxxxxxxxx> wrote: >> > Elias >> > looks very interesting. >> > 1. How will it impact VM , swappers , raids ? >> >> What exactly do you want to know? As long as the disk is parked, you can >> do no I/O on it, i.e. no swapping is possible. Since I don't know >> anything about the implementation of raids and don't have a raid setup >> here, I can't really tell how a raid device will behave exactly when one >> of its disks has been parked. Generally, all I/O will be delayed until >> the disk is unparked again. >> > 2. you said it has no value for servers ? did you try ? >> >> Again, I'm not quite sure what you want to know. Obviously, desktops or >> servers for that matter can have disks installed that support the unload >> feature. On these devices you can use the interface as described in my >> document. All I'm saying is that the interface has been designed with >> laptops in mind because I don't see in which situation immediate head >> unloading would be required or even desirable in a classical server >> environment. > I will rephrase. does head parking increase reliability ( MTBF ... MTTF ) of a disk ? > My servers hardly generate IOs at night times, does head parking at nights extend > the life of a disk ? or is it the opposite ? does it matter ? Disk head parking is meant as a short term emergency resort. In general, it does *not* extend the lifetime of a disk. In fact, emergency head unloads are considered to be costly and smart even counts those events as an aging factor. It really is just a means to prevent even worse damage due to heavy shocks, nothing for regular maintenance. Hope that helps, Elias -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
