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#1 2008-03-31 06:20:29

whaler
Member
From: Oslo, Norway
Registered: 2008-03-25
Posts: 310

Arch64 + RAID1 + multiboot - is it possible?

I am very happy with Archlinux' performance on another machine and would like to try installing its 64-bit version on an unused software RAID set (two disks, planned as RAID1) on my main box.

However, I am a bit scared...

1. When I installed Arch 32-bit on my other box, the bootloader was placed in the MBR without warning and my explicit permission. Luckily, I had no other OS's on that box. Is there a way to avoid having the installer screwing up a system with other OS's already installed?

2. How easy/difficult is it to set up Arch64 on a RAID1 configuration? I have read the Software Raid How-To, but I am not sure if it is up to date and whether there are new(er) things I should be aware of...

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#2 2008-04-01 11:59:19

loosec
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Registered: 2007-03-08
Posts: 134

Re: Arch64 + RAID1 + multiboot - is it possible?

Software RAID and multiboot is probably possible if you only use linux distros, mixing in windows would as far as I know not be possible. Software being using mdadm and naming the devices /dev/md0 etc.

If you mean BIOS controlled Software RAID it is more likely possible. This would use dmraid to detect your RAID sets and they would be called /dev/mapper/[drivername]_[randomletters]1 etc.
http://wiki.archlinux.org/index.php/Ins … _Fake-RAID is currently up to date, software-raid guide should be too.

From what I read it sounds like you have set up your RAID set in BIOS since you have a Mirror built from two entire disks, so the Fake-RAID guide is what you're looking for. Software RAID can only create stripes/mirrors from partitions on disks, not the whole disk itself.

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#3 2008-04-01 14:05:35

whaler
Member
From: Oslo, Norway
Registered: 2008-03-25
Posts: 310

Re: Arch64 + RAID1 + multiboot - is it possible?

loosec wrote:

(...) From what I read it sounds like you have set up your RAID set in BIOS since you have a Mirror built from two entire disks, so the Fake-RAID guide is what you're looking for. Software RAID can only create stripes/mirrors from partitions on disks, not the whole disk itself.

Thanks. Yes, you are right - a Fake-RAID is what I should have had in mind wink In the meantime I have tried to study a bit myself and have started to wonder whether it is worthwhile, given the extra burden on the CPU(s).

I have two SATA disks which have been sitting idle for more than a year, and I know I could not make XP detect them until I had configured them as a RAID in BIOS. I then said goodbye to Win**** and got lost in Linux and I still don't know whether it is possible to use my SATA disks as single, "ordinary disks... Apart from deactivating the RAID setup in BIOS, is there something else I must do to make Arch detect and use them as single disks?

TIA.

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#4 2008-04-01 19:27:18

loosec
Member
Registered: 2007-03-08
Posts: 134

Re: Arch64 + RAID1 + multiboot - is it possible?

Hmm, so you don't want to use raid.

If you just create a partition on /dev/sda or /dev/sdb and they both are part of a raid set I guess it should work and you would be able to see them and access them properly, however your bios raid check on boot would most likely scream out loud and demand a disc check of the raid set.

Disabling the BIOS RAID should be all you need to do. That and repartition the disks.


Fake-RAID is really easy to set up thou and the burden on your cpu should not be a problem. What takes cpu cycles is raid-5 etc that has to calculate checksums. Raid 0 and 1 is a no-brainer, split or duplicate.

Then again if you're planning on only using linux you could go with pure software raid. Benchmarks should be on the same level.

Good luck! smile

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#5 2008-04-02 01:30:35

whaler
Member
From: Oslo, Norway
Registered: 2008-03-25
Posts: 310

Re: Arch64 + RAID1 + multiboot - is it possible?

loosec wrote:

What takes cpu cycles is raid-5 etc that has to calculate checksums.

I will probably try installing to a fake raid-1 after all then roll

Thank you for clearing up this and a couple other things. Much appreciated!

Last edited by whaler (2008-04-02 01:31:25)

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#6 2008-04-02 06:48:21

wantilles
Member
From: Athens - Greece
Registered: 2007-03-29
Posts: 327

Re: Arch64 + RAID1 + multiboot - is it possible?

whaler wrote:

When I installed Arch 32-bit on my other box, the bootloader was placed in the MBR without warning and my explicit permission.

The question was there.

You just did not pay attention.

The Arch installer never does anything without the explicit permission of the user.

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#7 2008-04-02 07:26:19

loosec
Member
Registered: 2007-03-08
Posts: 134

Re: Arch64 + RAID1 + multiboot - is it possible?

Just tried out the latest iso, and it's alot simpler to install now since the correct package is already on it.

Probably want to to the following to be sure of a working system:

dmraid -ay
ls -l /dev/mapper


in the setup, go for OTHER disk and enter correct raid set from /dev/mapper/

When choosing packages, dmraid should have been chosen for you.

When editing /etc/mkinitcpio.conf make sure dmraid is one of the hooks and your raid chipset driver is in modules.

You might have to install grub the weird way described in wiki on Fake-RAID, not sure yet, will test.

That should be about all.

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#8 2008-04-02 07:40:36

whaler
Member
From: Oslo, Norway
Registered: 2008-03-25
Posts: 310

Re: Arch64 + RAID1 + multiboot - is it possible?

wantilles wrote:
whaler wrote:

When I installed Arch 32-bit on my other box, the bootloader was placed in the MBR without warning and my explicit permission.

The question was there.

You just did not pay attention.

The Arch installer never does anything without the explicit permission of the user.

Read the above again: "... without warning AND ..."

Too many installers act this way. It may probably be said to be default. Nevertheless, this is bad, i.e. dangerous, behaviour, based on an unfounded assumption about being the sole OS on the box, cf. Win****. IMO the bootloader should always be placed on the partiton unless the user wants it in the MBR. At the very least, the installer should present a warning and the choice.

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#9 2008-04-02 08:26:37

loosec
Member
Registered: 2007-03-08
Posts: 134

Re: Arch64 + RAID1 + multiboot - is it possible?

Windows Xp does this, as soon as you choose what disc to install to it overwrites mbr.

In Arch you must at least choose Install GRUB and choose the discs mbr or a partition on that disc. /dev/sda being mbr. This might not be explicitly stated but it is imo the most logical way.
Perhaps a flashy warning sign should appear when choosing mbr.

Anyway good luck with installing and give some feedback to the wiki when you succeed! smile

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#10 2008-04-03 06:27:35

whaler
Member
From: Oslo, Norway
Registered: 2008-03-25
Posts: 310

Re: Arch64 + RAID1 + multiboot - is it possible?

loosec wrote:

This might not be explicitly stated but it is imo the most logical way.
Perhaps a flashy warning sign should appear when choosing mbr.

Yes, an explicit statement/explanation/warning or some such ought to exist, given that not everybody are tinkering with computers and aware of the pitfalls. Of course, one might argue that Arch isn't for everybody, or that people who want to dual-boot should read up before proceding, but even experts can get distracted and forget to edit the destination address in Grub before pushing <Enter>. This may be a sore point with me, as a long time OS/2 user, but even the old Slackware installer issues a warning about this smile

Archlinux is working smoothly on my old Compaq and I am slowly building up courage to install it on my main machine...

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#11 2008-04-21 16:43:44

lilsirecho
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Registered: 2003-10-24
Posts: 5,000

Re: Arch64 + RAID1 + multiboot - is it possible?

loosec;

Have had the raid setup in mdadm for some time.

Noted that my pdc module is installed in my modules array.

I have downloaded dmraid and examined its params.  It recognizes my raid devices.

However, I desire to use the raid to boot my system.  The system is FaunOS "Live" and is usually booted from a flash device using a usb.img for installing.  There exists a DVD .iso as well which might be easier to work with.

I have attempted to use the commands you posted...dmraid -ay...ls -l /dev/mapper... and I get no such file or directory...

Basically, I understand that I must include dmraid in hooks and change grub to allow for root assignment and the CHS values.  These seem to be available in device-mapper according to the fake-raid setup.

It seems that dmraid stands for device mapper raid but my system lacks the mapping function.  Device mapper is included in installed packages.  A reference to device mapper driver is made in fake-raid wiki.

Perhaps the latest kernel has changes which enable the dmraid more directly.  I have yet to install the .4-1 kernel.

Present setup works fine but not for boot.  To enable booting, I assume that the root designator will permit the system to accept the raid device through device mapper ID as long as I have the hook for dmraid.

Perhaps there are new methods?


Sign of the times: Navajo blanket..made in China
Hard work does not kill people but why risk it: Charlie Mccarthy
A man is not complete until he is married..then..he is finished.
When ALL is lost, what can be found? Even bytes get lonely for a little bit!     X-ray confirms Iam spineless!

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#12 2008-04-22 15:44:33

lilsirecho
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Registered: 2003-10-24
Posts: 5,000

Re: Arch64 + RAID1 + multiboot - is it possible?

Continuing activity in the "live" faunOS system, I installed dmraid hook in the operatind system.

I generated a BIOS raid0 array of two flash drives...compact flash 2GB IDE compatible UDMA ad Hde and Hdg. 

While booted into FaunOS I ran the following commands as root:
                  dmraid -r
                root@n6re ~]# dmraid -r
/dev/hdg: pdc, "pdc_eejfihfd", stripe, ok, 4021760 sectors, data@ 0
/dev/hde: pdc, "pdc_eejfihfd", stripe, ok, 4021760 sectors, data@ 0

                  dmraid -ay
                  ls -l /dev/mapper
                 
                 

[root@n6re ~]# dmraid -ay
[root@n6re ~]# ls -l /dev/mapper
total 0
crw-rw---- 1 root root  10, 62 2008-04-22 08:05 control
brw------- 1 root disk 254,  0 2008-04-22 08:25 pdc_eejfihfd
brw------- 1 root disk 254,  1 2008-04-22 08:25 pdc_eejfihfd1

The next activity called for in the fake wiki was unsuccessful...cfdisk did not provide a response to the command:

                  cfdisk /dev/mapper/raid_set

I am hopeful that I can proceed to generate a raid_set by some other means since this seems to be the key to further implementation.


Sign of the times: Navajo blanket..made in China
Hard work does not kill people but why risk it: Charlie Mccarthy
A man is not complete until he is married..then..he is finished.
When ALL is lost, what can be found? Even bytes get lonely for a little bit!     X-ray confirms Iam spineless!

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#13 2008-04-25 11:21:07

loosec
Member
Registered: 2007-03-08
Posts: 134

Re: Arch64 + RAID1 + multiboot - is it possible?

In your case the raid set would be pdc_eejfihfd so you should most likely run

cfdisk /dev/mapper/pdc_eejfihfd

There is no reason it should not work since dmraid -ay found this set and put it in /dev/mapper/

edit: note that the latest ISO's have added support for dmraid in the installer so it's alot easier now.

Last edited by loosec (2008-04-25 11:22:39)

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#14 2008-04-25 16:20:45

lilsirecho
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Registered: 2003-10-24
Posts: 5,000

Re: Arch64 + RAID1 + multiboot - is it possible?

Performed the suggested command and received....fatalerror, cannot open disk drive...

The listing in /dev/mapper is correct.


Sign of the times: Navajo blanket..made in China
Hard work does not kill people but why risk it: Charlie Mccarthy
A man is not complete until he is married..then..he is finished.
When ALL is lost, what can be found? Even bytes get lonely for a little bit!     X-ray confirms Iam spineless!

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#15 2008-04-28 10:54:55

loosec
Member
Registered: 2007-03-08
Posts: 134

Re: Arch64 + RAID1 + multiboot - is it possible?

Driver problems then? Or somehow a corrupt raid set. No idea what to do about it.

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