From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roger Heflin Subject: Re: Good hardware for mdadm Date: Sat, 30 Aug 2014 04:53:48 -0500 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Paul van der Vlis Cc: Linux RAID List-Id: linux-raid.ids That means you need an external config tool (serial, ilo or IMM that allows remote console access), I rarely go into the data center that all of the hw I run is in, and because of the remote console access can fix all but truly broken hw without having hands in the DC). For most low end enterprise hw this option adds $200-300 to the price. If using the simplest (serial) the given mb bios must support serial and all add-on bioses must also properly support serial. I have messed with machines that when using serial you cannot see/access some of the add on bioses which limits what you can do. ILO/IMM (full graphics console remote type setups) don't have this deficiency and can in some cases actually allow one to present a remote boot cd to a device and rescue boot it. The MBR did not get broken, it was broken like this as originally designed 30 years ago, it was always setup to be only able to deal with totally dead drivers (ie drive not showing up at all). On Sat, Aug 30, 2014 at 3:35 AM, Paul van der Vlis wrote: > op 30-08-14 00:38, Roger Heflin schreef: >> No bios I have seen automatically handles it unless the disks are >> total dead, > > That's my experience too. > >> some of the hardware raid controlers may properly deal >> with a disk returning an error and go to the other mirror, the low end >> quality raid controllers start around $200. > > Hardware raid controllers have other disadvantages, like using a > proprietary format for storing information on disk. And in many cases > you have to use tools from the manufacturer. That are reasons for me to > like mdadm. > > Maybe it could be done with a hardware raid controller in JBOD mode. > > ( And hardware controllers are not perfect too, I've seen simular > problems with an HP smart array. First when I've removed the first > harddisk the system did boot from the second. ) > >> Outside of the raid controllers I don't believe any of the bioses >> themselves will do it, so you are unlikely to find any hardware that >> does that. > > It could be done with a PCIe card too. Some kind of fake-raid adapter > what uses mdadm. > >> Likely he is talking about putting the boot block on multiple disks >> and and use the bbr menu or the bios boot disk selection to pick >> another disk. > > Not sure what a "bbr menu" is. But realize that the servers I use are > remote. > > With regards, > Paul van der Vlis. > >> On Fri, Aug 29, 2014 at 4:47 PM, Paul van der Vlis wrote: >>> Hi Roberto, >>> >>> op 29-08-14 22:44, Roberto Spadim schreef: >>>> i use two or more boot disks, if the first raid1 disk don't boot bios >>>> go to second boot disk, third, etc etc, >>> >>> In my opinion this only works when the boot-disk is completely defect or >>> removed. Not when the data in the MBR on that boot-disk is corrupt. >>> >>> Or did you test this, or do you have other reasons to believe that your >>> bios will handle this correct? >>> >>> With the boot-disk I mean the disk what's in the bios the first disk. So >>> this could also be the second raid1 disk. Or an USB stick. >>> >>>> you must write grub to mbr of each disk >>> >>> Of course. >>> >>> With regards, >>> Paul van der Vlis. >>> >>>> i'm using dell server r410 if i'm not wrong >>>> >>>> 2014-08-29 17:31 GMT-03:00 Paul van der Vlis : >>>>> Hello, >>>>> >>>>> I like mdadm and I am using it many years. But in my opinion it has one >>>>> disadvantage: when the MBR of the boot-disk is corrupt, the machine will >>>>> not boot. >>>>> >>>>> A bios could check this. Wait for some kind of signal from Grub or >>>>> Linux, and after a timeout boot from another disk. But I don't know >>>>> about a bios with that feature. >>>>> >>>>> A PCIe card could do something like that, but I don't know about such a >>>>> PCIe card. >>>>> >>>>> Is there such hardware? >>>>> What do you do to avoid this problem? >>>>> >>>>> With regards, >>>>> Paul van der Vlis. >>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> Paul van der Vlis Linux systeembeheer, Groningen >>>>> http://www.vandervlis.nl/ >>>>> >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >>>>> the body of a message to majordomo@vger.kernel.org >>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> >>>> >>>> >>> >>> >>> >>> >>> >>> -- >>> Paul van der Vlis Linux systeembeheer, Groningen >>> http://www.vandervlis.nl/ >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > > > > > -- > Paul van der Vlis Linux systeembeheer, Groningen > http://www.vandervlis.nl/ > > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html