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#1 2006-03-20 16:49:43

chane
Member
Registered: 2003-12-02
Posts: 93

RAID 5 Crash

I just installed RAID 5 according to the wiki instructions and everything worked great (after a minor hickup on my part).

I am now "testing" the array.  While powered down, I unplugged hdc and attempted to reboot.  Here are the messages on powerup

....
SGI XFS Quota Management subsystem
mdadm: cannot open device /dev/hdb3: No such device or address
mdadm: /dev/hdb3 has no superblock - assembly aborted
EXT2-fs: unable to read superblock
mount: Mounting /dev/root on /new_root failed: invalid argument
pivot_root: pivot_root: no such file or directory
umount: /initrd: no such file or directory
umount: /initrd: no such file or directory
Initial RAMDISK Loading Completed...
Freeing unusec kernel memory: 252k freed

BusyBox v1.01 (2006.01.03-14:15+0000) Built-in sheel (ash)
...

I tought that when one of the drives failed in a RAID 5 that the array should still be able to function?  Maybe functions if failed while power is on but will not initialize the array on a power up?

Machine Specs:
2 PIII
3 IDE Drives
  - hda primary 1
  - hdb slave 1
  - hdc primary 2

This is just a testing configuration while I wait for a new machine to arrive that will be using 4 sata drives (3 + hot spare).

Any help to figure out why the array is not being initialized is much appreciated.

Thanks,
Chris....

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#2 2006-03-20 21:54:56

The_Nerd
Member
From: Syracuse, NY / Baltimore, MD
Registered: 2005-11-30
Posts: 134
Website

Re: RAID 5 Crash

i have never followed the wiki instructions but did you make sure that your formatted/partitioned the array properly? I found that the last time i made my raid 5 array i improperly partitioned/formatted one of my harddrives and every time i rebooted it came up a blank. thank goodness that i was running a raid 5 and my data was saved. i only had to repartition that one drive and reboot.

I would check out

http://www.tldp.org/HOWTO/Software-RAID-HOWTO.html

thats the most comprehensive guide around (i assume your using software raid).

hopefully that helps, i've been running two software raid 5's for about 4 years now, and its been well worth it.

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#3 2006-03-20 23:14:31

chane
Member
Registered: 2003-12-02
Posts: 93

Re: RAID 5 Crash

Thanks for the reply.

Your comment on formatting correctly triggered a question.

I have a running array (RAID 5) formatted and partitioned correctly.  After it is running (booted multiple times without issue and executed lots of filesystem commands that read/wrote data) I added a spare drive:

> mdadm /dev/md0 -a /dev/hdd3

The array sees this new "d" drive as a spare.  I then fail/remove one of the drives from the array.

> mdadm /dev/md0 -f /dev/hdb3
> mdadm /dev/md0 -r /dev/hdb3

The software array removes the b drive and puts the d drive into the array.  It then starts the sync process.  Someway through the sync process I get a fail to sync error that the drive is bad and it is being removed from the array.  I'm also sure the drive is good.  It has been running in another computer for years now.

I'm sure the partition size on the d drive is correct (just checked it again).  But I did not "format" the drive partition.  I figured that would happen when the drive was sync'ed up with the other 2 in the array.

Question is: do I have to "format" a drive before I can add it to the RAID array?

Thanks,
Chris....

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#4 2006-03-21 00:32:12

The_Nerd
Member
From: Syracuse, NY / Baltimore, MD
Registered: 2005-11-30
Posts: 134
Website

Re: RAID 5 Crash

to be honest i cant remember exactly what i did. :oops:

hinking about it logically, i wouldnt see why you would have to format it since the rebuilding process would theortically write sectors that create the filesystem and contain any data if i'm not mistaken. you may want to go one step farther than checking the partition size of that other drive, i'd take it out, delete the partition fully, then re-create it to proper size and label it a "FD" partition so it is marked as raid array autodetect. then you may as well format it for the heck of it, what do you have to loose other than mabye a minute while it formats the drive. i wish i could try this out here at home, but my 1.5tb of space is just about full with everything from backups of client computers (i run a computer repair business out of my house) to my dvd collection, i just dont have the space to try it out.

if i get the chance, mabye i'll roud up some little 3gb drives and give it a shot.

i wish i had a definitive answer for ya, but why not try repartitioning and reformatting the hdd drive.

one final note! i just thought about this as i was writing, when i added a 4th drive to my 3 drive array, while it was building the drive read as a spare. unless you specifically designated the drive as a spare in your config or with the mdadm parameter (which it doesnt look like you did, again i cant remember what the options for mdadm are and i'm not near a linux computer at the moment) then it will add the drive as a 4th drive in the array and it will begin building it in. then when you removed the hdb drive, it will see the array as having two failed disks, or one that is incomplete and one that has been removed, which may result in the "fail to sync" error. in this case i daresay that your data is lost, but id try it with the 3 drives again and see if it would assemble itself with a drive down situation.

best of luck! hope it turns out well.

(ps if you would like me to do a detailed look into it, i may be able to come up with exactly how i've set mine up, im just really busy with school work at the moment and i may not be able to get to you right away)

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#5 2006-03-21 15:52:02

chane
Member
Registered: 2003-12-02
Posts: 93

Re: RAID 5 Crash

Thanks for the offer for more help.

Rather than have you spend time with my science fair project, I am ordering new hardware.  I believe the test environment I was able to clob together is so old that the it just doesn't like me pushing the limits.  I also think it might be an IDE controller issue (bios/motherboard is over 5 years old).  The Sata controller/drive that I have doesn't work in the system either.

Once I get the new hardware, I will be playing with it aggresively to make sure all this stuff works correctly.  I'm pretty sure I'm close to having it right.

As for mdadm, when I added the fourth drive and then did:
> mdadm --misc --detail /dev/md0

This command listed all four drives and said that the fourth one was a spare.  I initially had the same thought as you about how to add it as a spare, but it appears that mdadm will not increase the number of drives in the array...

Thanks for you help,
Chris....

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#6 2006-03-21 20:19:47

The_Nerd
Member
From: Syracuse, NY / Baltimore, MD
Registered: 2005-11-30
Posts: 134
Website

Re: RAID 5 Crash

good luck once you get the new parts! i've had great luck with highpoint controllers and my array, i currently have two, 4 port ata controllers running 4, 120gb drives in RAID 5 and 4, 200gb drives in RAID 5.

Just for further refrence:

Dual athlon mp 1600+
1024mb ddr
tnt2 video
intel e1000 gigabit ethernet
600gb raid 5 array
360gb raid 5 array

i've been running it for years now and ive never had a problem hosting, files, a website, and some pretty large LAN's with it over the years. if your just talking fileserver, anything more than this would probably be overkill but if your looking into a motherboard, make sure it has 64bit pci or pci-x slots for raid cards. it makes a WORLD of difference. also, make sure you have a power supply that can handle the harddrives you put into the system.

please let me know how it comes out, and if you have any problems setting it up let me know. i think i will be upgrading my 120gb's to 300gb drives in the near future and i will do my best to document the process better and add to the wiki anywhere where it may be necessary.

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#7 2006-03-22 01:47:14

chane
Member
Registered: 2003-12-02
Posts: 93

Re: RAID 5 Crash

Thanks for the info.  I will post back when I get the new hardware in, altough it's probably going to be a couple of weeks....

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#8 2006-03-23 19:24:58

chane
Member
Registered: 2003-12-02
Posts: 93

Re: RAID 5 Crash

The_Nerd,

Quick question if you don't mind.  With your RAID setup, are you booting off of the array?  We are probably going to try and do that.  I was wondering about your experience...

Thanks,
Chris....

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#9 2006-03-23 21:04:38

The_Nerd
Member
From: Syracuse, NY / Baltimore, MD
Registered: 2005-11-30
Posts: 134
Website

Re: RAID 5 Crash

i am not currently.

i was booting off of a raid 1 when i used slackware but when i decided to install arch i just moved to a single drive because i needed to get my server back up fast. i havent had any problems with it so i'm still running a single drive. i have actually been thinking of buying two 80gb drives to put into a raid1 drive to run the operating system off of, but as for experience in the matter, i cant offer you too much.

that being said, i did boot off of a software raid 5 on another one of my servers. i had an old 3 drive scsi computer that i setup a few months ago. set it up in raid 5 and was able to boot and install everything from it and it worked like a charm. if i remember correctly, i followed the linux software raid howto to setup the drives etc, then followed the instructions on the wiki for setting it up. i had it working in about an hour ( i needed it for a LAN party) but again, in my true form, i did not document the process at all.

i would hope that you would have no problems following the instructions you can find on the wiki. if you end up not being able to do it, drop me a line and i'll see how i can help. i may also have time this weekend to try out that 3 drive fileserver again. if i do, i'll let you know exactly how to do things.

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#10 2006-04-21 14:57:55

chane
Member
Registered: 2003-12-02
Posts: 93

Re: RAID 5 Crash

Well, it took longer to get my new hardware than I expected.  I just got it in and things look (ed) good.

We got the system up and running following the directions on the wiki.  Then I started to "test" and was wondering a couple of things and what I should expect to work:

The setup:
3 - drives with 3 partitions apiece
(md1) part1 - 100 MB boot (raid 1)
(md2) part2 - 4 GB    swap (raid 1)
(md0) part3 - 356 GB  / (raid 5)

1. I have a fourth drive that I want to add as a hot spare.  When I issue the command > mdadm --manage /dev/md0 -a /dev/sdd3
   - the drives gets added to the array as a spare
   - when the computer is rebooted, the spare no longer is shown
     when I do a >mdadm --misc --detail /dev/md0
   - altough if I do >mdadm -E /dev/sdd3 it says it's in the array

2. After the three drives synch'ed (2.5 hours), I removed the b drive and rebooted, the system would not completely boot
   - I get the busybox prompt
   - I can post the startup messages; I figued there might be something
     that I shouldn't be doing

Any thoughts?  I'm in the process of reinstalling arch (7.1) again to make sure I didn't mess something up trying to add the spare in....

I new to using raid and am trying out different things to make sure I understand how it works before I put it into production.  Hopefully soon cause we really need the boost from the new hardware...

Thanks,
Chris....

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