Hi Everyone, Not really a Xen question, but I''m sure someone here will know the answer. Is it possible to install a linux distro (CentOS) on a system that has RAID1 set up under "software RAID"? I have a machine that can only fit 2 disks, and no hardware RAID controller.. Thanks Jonathan _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> Hi Everyone, > > Not really a Xen question, but I''m sure someone here will know theanswer.> > Is it possible to install a linux distro (CentOS) on a system that hasRAID1> set up under "software RAID"? I have a machine that can only fit 2disks, and> no hardware RAID controller.. >Debian can configure and install onto RAID1 just fine, with LVM on top too (except for /boot, although that info might be out of date if grub2 can read from lvm volumes). I assume any other recent distro is capable of similar. James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi Jonathan, Depends on you method: I would recommend to use the Linux Software Raid with mdadm. Just look at some tutorials / howtos, mdadm can be used quite straightforward (Google for mdadm or Linux software raid 1). You create usual partitions on a disk, which are marked by id fd for raid autodetect. The kernel scans those devices and handles software RAID automatically. The RAID devices are named /dev/mdX usually and can be formated with a filesystem or used for LVM. You can also combine RAID and non-RAID partitions or RAID-0 and RAID-1 devices on one pair of disks. If you want to use those Fake-RAID stuff of modern SATA-Controllers, I personally prefer plain software raid. This is usually used as Software RAID for Windows, because Windows doesn''t handle software RAID itself, but the Windows SATA driver does. Linux doesn''t need any hardware capabilities for software raid. Regards, Felix Am 24.06.2010 14:48, schrieb Jonathan Tripathy:> Hi Everyone, > > Not really a Xen question, but I''m sure someone here will know the answer. > > Is it possible to install a linux distro (CentOS) on a system that has > RAID1 set up under "software RAID"? I have a machine that can only fit > 2 disks, and no hardware RAID controller.. > > Thanks > > Jonathan > > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Thursday 24 June 2010 14:48:28 Jonathan Tripathy wrote:> Hi Everyone, > > Not really a Xen question, but I''m sure someone here will know the answer. > > Is it possible to install a linux distro (CentOS) on a system that has > RAID1 set up under "software RAID"? I have a machine that can only fit 2 > disks, and no hardware RAID controller.. > > Thanks > > Jonathan >Hi Jonathan, Xen doesn''t really care how the storage is configured as long as the Dom0 (Host) can access it. I use software RAID as well and my Xen domains have no problem with it. -- Joost _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 24/06/10 13:48, Jonathan Tripathy wrote:> > Is it possible to install a linux distro (CentOS) on a system that has > RAID1 set up under "software RAID"? I have a machine that can only fit > 2 disks, and no hardware RAID controller.. >Yes. Pay attention during the install, you can create raid disks in the graphical disk layout thingy. Piece of cake. jch _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
>Yes. Pay attention during the install, you can create raid disks in the graphical disk layout thingy.Excellent! _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > If you want to use those Fake-RAID stuff of modern SATA-Controllers, I > personally prefer plain software raid. This is usually used asSoftware RAID> for Windows, because Windows doesn''t handle software RAID itself, butthe> Windows SATA driver does. Linux doesn''t need any hardware capabilitiesfor> software raid. >Windows does do software mirroring, but IMHO it is not recommended. The _only_ advantage that Fake-RAID might have over Linux software raid is in the case where a drive fails in such a way that the BIOS starts to boot off it but fails due to bad sectors on a disk before the Linux RAID is loaded (eg the bootsector loads, but the blocks containing GRUB are unreadable). If the disk fails completely then you are probably fine as the BIOS will just boot from the next disk (which you have hopefully installed the bootsector on too!), but if the unreadable parts of the disk contain GRUB then you will most likely hang or enter a reboot loop. Fake-RAID should be able to cope with this, at least up to the point where the INT13 disk interface is still used... James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
If I installed CentOS with RAID1 using software RAID, would it work in such a
way that if I were to remove one drive, the system would continue to function?
I''m having a hard time understand this. Everytime I think it through in
my head, I end up in a "chicken-and-egg" suitation...
Thanks
________________________________
From: xen-users-bounces@lists.xensource.com on behalf of Jonathan Tripathy
Sent: Thu 24/06/2010 14:11
To: John Haxby; xen-users@lists.xensource.com
Subject: RE: [Xen-users] Software RAID
>Yes. Pay attention during the install, you can
create raid disks in the graphical disk layout thingy.
Excellent!
_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users
Yes, it should... But (I believe) if you are using the pygrub bootloader you would need to install grub on both drives, else it would be like booting a bare system with 2 software RAID drives where if you pull the drive with the GRUB boot loader on it, there would be no grub to boot off the remaining disk. I believe that if you are using the other type of setup where you specify kernel and ramdisk in config then it should boot after removing a disk and the system should then complain about operating in ''degraded RAID mode'' since MDADM should recognize a missing disk. I''m not a XEN guru however, so there may be some fundamental concepts I''m overlooking. On Fri, 2010-06-25 at 17:46 +0100, Jonathan Tripathy wrote:> If I installed CentOS with RAID1 using software RAID, would it work in > such a way that if I were to remove one drive, the system would > continue to function? > > I''m having a hard time understand this. Everytime I think it through > in my head, I end up in a "chicken-and-egg" suitation... > > Thanks > > > ______________________________________________________________________ > From: xen-users-bounces@lists.xensource.com on behalf of Jonathan > Tripathy > Sent: Thu 24/06/2010 14:11 > To: John Haxby; xen-users@lists.xensource.com > Subject: RE: [Xen-users] Software RAID > > > > > > > > >Yes. Pay attention during the install, > you can create raid disks in the graphical disk layout thingy. > Excellent! > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Sorry, I forgot to mention that this isn''t really a Xen related issue. I will be installing CentOS from scratch on a bare metal system (while will be running Xen eventually, of course) -----Original Message----- From: DoubleHP [mailto:doublehp@doublehp.org] Sent: Fri 25/06/2010 18:07 To: Jonathan Tripathy Subject: Re: [Xen-users] Software RAID On 25/06/10 18:46, Jonathan Tripathy wrote:> If I installed CentOS with RAID1 using software RAID, would it work in > such a way that if I were to remove one drive, the system would continue > to function? > > I''m having a hard time understand this. Everytime I think it through in > my head, I end up in a "chicken-and-egg" suitation... > > ThanksRaid1 is designed to resist disk failure. You need to explain your configuration in details if you want us to tell what we think about it. I can'' see how this can be Xen related. You have the dom0. It performs certain actions, and, dom0 is, by itself, a layer. On top of this layer, you add more stuff. Write it down on a paper, layer by layer (i do it upside down in this email) - disks - disk controller, can be hard raid - dom0 kernel - mdadm optionnal - LVM optionnal - dom0 system - xen - domU kernel - mdadm optionnal - LVM optionnal - domU system It also depends if you use HVM or not ... You write where your disks are, and where you did your soft raid, and, things will look trivial after that :) -- >o_/ DEMAINE Benoit-Pierre (aka DoubleHP) http://benoit.demaine.info/ If computing were an exact science, IT engineers would''nt have work \_o< "So all that''s left, Is the proof that love''s not only blind but deaf." (FAKE TALES OF SAN FRANCISCO, Arctic Monkeys) _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users