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#1 2006-11-27 17:56:28

brazzmonkey
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From: between keyboard and chair
Registered: 2006-03-16
Posts: 818
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matrix raid and linux ?

hi everyone,
i bought a laptop a few days ago. it features 2 HD, and raid support is available (after a bios update). i don't know anything about RAID, and from what i read, RAID 0 is for performance, RAID 1 is for data redundancy, and RAID matrix seems to combine both RAID 0 and 1.

i plan to install Linux on this laptop (which of course came with some M$ shit). does linux support intel matrix raid ? any advices or things i should take care of before proceeding ?

tia !


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#2 2006-11-28 07:30:54

brazzmonkey
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From: between keyboard and chair
Registered: 2006-03-16
Posts: 818
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Re: matrix raid and linux ?

no RAID expert in here ??


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#3 2006-11-28 07:57:14

iphitus
Forum Fellow
From: Melbourne, Australia
Registered: 2004-10-09
Posts: 4,927

Re: matrix raid and linux ?

not sure, but:

http://linux-ata.org/faq-sata-raid.html
http://linux.yyz.us/why-software-raid.html

ought to answer your question in some way or another -- the second one particularly. Seeing as the raid provided by your laptop is just software raid, you may as well just use straight linux software raid instead.

I've never used raid, but the links above are by Jeff Garzik, maintainer of the SATA subsystem and many other components -- he knows his stuff.

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#4 2006-11-28 08:58:02

brazzmonkey
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From: between keyboard and chair
Registered: 2006-03-16
Posts: 818
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Re: matrix raid and linux ?

ok, i give up. i dont't feel very confident about raid and that sort of stuff. i once used LVM on gentoo (great docs !), but i had time to experiment. i beleive i read somewhere gentoo and fedora install cd are the only ones that support (software) raid.

too bad i'm to o busy to get into something complicated. i'll probably just give kubuntu a shot on this laptop.

your help is much appreciated, iphitus !


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#5 2006-11-28 11:20:56

chrismortimore
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From: Edinburgh, UK
Registered: 2006-07-15
Posts: 655

Re: matrix raid and linux ?

By RAID "matrix", do you mean RAID 0+1 or RAID 10?  Because if you do, you need 4 drives for those.  You can do it with two drives and 2 partitions on each drive, but it'll give you a massive performance hit.

Given it is a two drive setup, I wouldn't recommend anything other than RAID 1. 
RAID 0 is dangerous, as there is no redundancy at all, all it takes is one little bad sector and your whole system can be up the creek.  If you have another box to back up to, you may consider it worth the risk, but I wouldn't. 
RAID 1 will give you redundancy, and because everything is mirrored, it has the potential to be twice as fast for reads.  Writes will, of course, be a little slower because it is sticking everything in two places.

If you don't feel confident and you have a spare day, qemu is your friend.  It won't give you any indication of performance, but it'll let you practise setting it all up.

Debian 3.1 installation discs support LVM and software raid as well.  Doesn't the Arch installer support it as well?  I can't comment on this one, as I've only done RAID in Debian and Gentoo.


Desktop: AMD Athlon64 3800+ Venice Core, 2GB PC3200, 2x160GB Maxtor DiamondMax 10, 2x320GB WD Caviar RE, Nvidia 6600GT 256MB
Laptop: Intel Pentium M, 512MB PC2700, 60GB IBM TravelStar, Nvidia 5200Go 64MB

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#6 2006-11-28 11:24:12

iphitus
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From: Melbourne, Australia
Registered: 2004-10-09
Posts: 4,927

Re: matrix raid and linux ?

arch ought to support software raid too, its just a matter of setting it up, maybe theres something on the wiki

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#7 2006-11-28 11:33:52

chrismortimore
Member
From: Edinburgh, UK
Registered: 2006-07-15
Posts: 655

Re: matrix raid and linux ?

I've just read up about "Matrix" RAID, and it isn't anything special (read about it here: http://www.intel.com/design/chipsets/ma … ge_sb.htm).  All it does is it lets you have many RAID levels on the same set of drives.  So you can have RAID 0 (performance) for your main working, and RAID 1 on the same drives for storage. 

Linux software RAID lets you do this anyway.  With software RAID, you set up partitions for your RAID array on the disc using any old partitioner.  You can then join the partitions together in any way you like to make your RAID array, and you can have as many RAID arrays as you can think of.  You could do something like this:

RAID partitions:
/dev/md0: /dev/sda1 and /dev/sdb1 in RAID 1
/dev/md1: /dev/sda2 and /dev/sdb2 in RAID 0
/dev/md2: /dev/sda3 and /dev/sdb3 in RAID 1

Once you have configured the arrays like this, you can then do "mke2fs /dev/md0" and use this one as your /boot device (grub can read RAID 1 arrays)
Set up an LVM on /dev/md1, and install your distribution on here (/, /usr, /var, /opt, /tmp, etc).
Set up a separate LVM on /dev/md2, and put, say, /home, /usr/local/, /var/local/ and /backup/ on it.
Set up a cron script to backup all important things like /etc to /backup/.

This will have /home, /usr/local/, /var/local/ and all backup things in /backup/ on /dev/md2 (a nice safe RAID 1).  /boot/ will be on /dev/md0, a separate safe RAID 1.  And the rest will be on /dev/md1, giving you maximum speed.  Thus all files you manage will be stored with redundancy, making recovery easy.

I probably made it sound really complicated, but it's actually quite simple to do, honest.  Just a little time consuming.


Desktop: AMD Athlon64 3800+ Venice Core, 2GB PC3200, 2x160GB Maxtor DiamondMax 10, 2x320GB WD Caviar RE, Nvidia 6600GT 256MB
Laptop: Intel Pentium M, 512MB PC2700, 60GB IBM TravelStar, Nvidia 5200Go 64MB

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#8 2006-11-28 12:30:35

chrismortimore
Member
From: Edinburgh, UK
Registered: 2006-07-15
Posts: 655

Re: matrix raid and linux ?

Using the setup I described in my last post, this is how a Debian system (in qemu) looks:

/dev/hda1: Linux raid autodetect
/dev/hda2: Linux raid autodetect
/dev/hda3: Linux raid autodetect
/dev/hdb1: Linux raid autodetect
/dev/hdb2: Linux raid autodetect
/dev/hdb3: Linux raid autodetect

root@debian:~# pvdisplay
  --- Physical volume ---
  PV Name               /dev/md2
  VG Name               user
<snip>
  --- Physical volume ---
  PV Name               /dev/md1
  VG Name               system
root@debian:~# lvdisplay
  --- Logical volume ---
  LV Name                /dev/user/home
  VG Name                user
<snip>
  --- Logical volume ---
  LV Name                /dev/system/root
  VG Name                system
<snip>
  --- Logical volume ---
  LV Name                /dev/system/swap
  VG Name                system
<snip>
root@debian:~# cat /proc/mdstat
Personalities : [raid0] [raid1]
md2 : active raid1 hda3[0] hdb3[1]
<snip>
md0 : active raid1 hda1[0] hdb1[1]
<snip>
md1 : active raid1 hda2[0] hdb2[1]
<snip>
root@debian:~# mount
/dev/mapper/system-root on / type ext3 (rw,errors=remount-ro)
<snip>
/dev/md0 on /boot type ext3 (rw)
/dev/mapper/user-home on /home type ext3 (rw)

There you go, /home on LVM on a RAID1, /boot on a different RAID1, and / on a different LVM on a RAID0.  Simple smile


Desktop: AMD Athlon64 3800+ Venice Core, 2GB PC3200, 2x160GB Maxtor DiamondMax 10, 2x320GB WD Caviar RE, Nvidia 6600GT 256MB
Laptop: Intel Pentium M, 512MB PC2700, 60GB IBM TravelStar, Nvidia 5200Go 64MB

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#9 2006-11-28 12:33:27

brazzmonkey
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From: between keyboard and chair
Registered: 2006-03-16
Posts: 818
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Re: matrix raid and linux ?

well, the special part is that i need to have a dual-boot system (i.e. i need to keep winxp partitions). as you mentioned this is time-consuming, and time isn't exactly somthing i have plenty of atm. and from my personal experience, i'd rather keep a simple partition layout than an over-optimized one. i'm gonna use this computer for work so it's probably not a good idea to mess things up.


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#10 2006-11-28 13:12:24

chrismortimore
Member
From: Edinburgh, UK
Registered: 2006-07-15
Posts: 655

Re: matrix raid and linux ?

If you have two keep winxp on it, then I'd go with a drive for winxp and a drive for linux?  Keeps everything separate.

I agree though, it's better to keep things simple.  I only have multiple partitions so I can mount most of my system read only.  But that's a different story for another time.


Desktop: AMD Athlon64 3800+ Venice Core, 2GB PC3200, 2x160GB Maxtor DiamondMax 10, 2x320GB WD Caviar RE, Nvidia 6600GT 256MB
Laptop: Intel Pentium M, 512MB PC2700, 60GB IBM TravelStar, Nvidia 5200Go 64MB

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#11 2006-11-28 15:04:17

brazzmonkey
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From: between keyboard and chair
Registered: 2006-03-16
Posts: 818
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Re: matrix raid and linux ?

well usually i use a disk for system stuff ( / , windows c:) + some partitions for data backups (daily sync cron job). i use the second disk the other way around : data + system backups. i also put swap partitions on the 2nd HD - don't know if it's the best solution though.

when i used gentoo i had several lvm partitions (/opt, /var, /usr, portage stuff...) -  way too complicated to maintain, and performance was barely improved... KISS is the way to go as usual... but i'm afraid i won't use arch on this laptop (i'm looking for out-of-the-box energy management and connectivity). shame on me...


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#12 2006-11-28 15:42:39

chrismortimore
Member
From: Edinburgh, UK
Registered: 2006-07-15
Posts: 655

Re: matrix raid and linux ?

It seems wasteful to backup information to the same drive.  To be honest, the only time I use backups is when hardware fails.  My preference for simple backup solutions is to just duplicate one drive to another of the same drive using rsync.  This is what I use now, and it gives me a backup that I can boot from, should my main drive go down. 

But backup schemes are all about personal preference really, just go with whatever works for you.


Desktop: AMD Athlon64 3800+ Venice Core, 2GB PC3200, 2x160GB Maxtor DiamondMax 10, 2x320GB WD Caviar RE, Nvidia 6600GT 256MB
Laptop: Intel Pentium M, 512MB PC2700, 60GB IBM TravelStar, Nvidia 5200Go 64MB

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#13 2006-11-29 10:02:13

brazzmonkey
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From: between keyboard and chair
Registered: 2006-03-16
Posts: 818
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Re: matrix raid and linux ?

no no no, i don't backup to the same drive, i backup important stuff to the _other_drive. surely it doesn't make sense to backup to the same drive...

so i have :
- hda : linux / and winxp c:, backup of important data ;
- hdb : data, backups of linux / and winxp

i'd copy everything on an extra, external disk i had one


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#14 2006-11-29 11:55:01

chrismortimore
Member
From: Edinburgh, UK
Registered: 2006-07-15
Posts: 655

Re: matrix raid and linux ?

Ah, my mistake.

Annoyingly, this thread is tempting me to set up RAID on my desktop...  But I really don't need it...  Arrgghh!!!  Temp...tation...too.....strong.........! *bursts into flames*


Desktop: AMD Athlon64 3800+ Venice Core, 2GB PC3200, 2x160GB Maxtor DiamondMax 10, 2x320GB WD Caviar RE, Nvidia 6600GT 256MB
Laptop: Intel Pentium M, 512MB PC2700, 60GB IBM TravelStar, Nvidia 5200Go 64MB

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#15 2006-11-29 15:09:13

brazzmonkey
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From: between keyboard and chair
Registered: 2006-03-16
Posts: 818
Website

Re: matrix raid and linux ?

lol ! who _needs_ it anyway ?it's just a matter of being a geek !
i do have another dilemma : i got kubuntu working on the laptop (no RAID - wink), and it seems quite functional. a little basic configuration is needed, but most stuff works out of th box. however some kubuntu specific stuff annoys me a little bit...

(little voice in me head) - install arch...
(me) - nonono i don't have time to play !
(little voice in me head) - yes but it's so much better...
(me) - damn it !
...


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#16 2006-11-30 18:18:46

chrismortimore
Member
From: Edinburgh, UK
Registered: 2006-07-15
Posts: 655

Re: matrix raid and linux ?

brazzmonkey wrote:

lol ! who _needs_ it anyway ?

Well who needs food that tastes nice?  Bad tasting food still fills the hole tongue  Sometimes it's nice to bask in life's little luxuries.  And RAID is cool.


Desktop: AMD Athlon64 3800+ Venice Core, 2GB PC3200, 2x160GB Maxtor DiamondMax 10, 2x320GB WD Caviar RE, Nvidia 6600GT 256MB
Laptop: Intel Pentium M, 512MB PC2700, 60GB IBM TravelStar, Nvidia 5200Go 64MB

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#17 2006-11-30 19:03:32

Blind
Member
From: Desert mountain
Registered: 2005-02-06
Posts: 378

Re: matrix raid and linux ?

big_smile

you have almost convinced yourself, chrismortimore!

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#18 2006-12-01 10:05:33

brazzmonkey
Member
From: between keyboard and chair
Registered: 2006-03-16
Posts: 818
Website

Re: matrix raid and linux ?

chrismortimore wrote:
brazzmonkey wrote:

lol ! who _needs_ it anyway ?

Well who needs food that tastes nice?  Bad tasting food still fills the hole tongue  Sometimes it's nice to bask in life's little luxuries.  And RAID is cool.

that's so damn right !


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