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Old 01-26-2009, 03:31 PM   #1
rajeshkerala
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How to simulate a RAID0 failure?


Friends,
I wish to implement software RAID 0 ( for educational purpose). Suppose if I am making a RAID 0 by means of the command

mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/hda5 /dev/hda6

and now /dev/md0 is created. I am mounting it on a directory called /raid0 and put some data into it.
But, when I tried to set the partition /dev/hda6 as faulty by means of the
command:
mdadm --fail /dev/md0 /deva/hda6, the o/p says it is set as faulty. but when I went to the /raid0 and accessed the data, it is still there. It should actually be not there, right? So, what mistake I am making. please help.
 
Old 01-26-2009, 03:38 PM   #2
Nermal
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Aye up,

Try this link: http://linux-raid.osdl.org/index.php...ng_and_testing

Remember Search engines are you friend...
 
Old 01-26-2009, 08:56 PM   #3
rajeshkerala
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Hi friend,
Thanks for that, but it is actually about other RAID methods, if one is faulty others will work, which is working for me. I am looking for RAID 0 implementation, in whihch even removing a faulty device also is not possible. Thank u.
 
Old 01-27-2009, 12:43 AM   #4
split917
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so if i'm understanding you correctly, you want to initiate a disk failure so that the logical partition becomes unavailable...? if that's the case, why not just pull/disconnect a disk.
 
Old 01-27-2009, 01:11 AM   #5
r3sistance
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Indeed, Raid 0 has no redunancy at all, if this raid0 is small and holds nothing important, format one half of it. But a Raid0 in that state just is not recoverable. Raid0 requires both partitions working as it literally splits all data half an half so once you lose half it's gone, unlike other raids which still have all the data should one device become faulty and can still operate but lose their redunancy (rather then the entire array)
 
Old 01-27-2009, 04:10 PM   #6
Tinkster
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Quote:
Originally Posted by split917 View Post
so if i'm understanding you correctly, you want to initiate a disk failure so that the logical partition becomes unavailable...? if that's the case, why not just pull/disconnect a disk.
Because it's hard to pull a partition ;) ... his raid
slices reside on the same hdd.
 
Old 01-29-2009, 11:07 AM   #7
rajeshkerala
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I think I got the answer for this. Please let me know this is correct.

1.make 2 partitions, hda5 and hda6
2.Make it /dev/md0 with Raid level 0.
3.make the file system with ext3 and mount it to a folder, say /raid0
4.cd /raid0
5.Touch file1 file2 file3.
6.fdisk /dev/hda
7.delete /dev/hda6
8.partprobe.
9.reboot.
10. cd /raid0
11.The system will give error message failing to read.
--------------------
but if you do the same procedure to a raid1 or raid5 still we can read the file1 file2 file3.
thank you friends.
 
  


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