Re: [gentoo-amd64] Upgrading to Raid

[Nuitari <nuitari@melchior.nuitari.net>]

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There is a huge difference between RAID5 and RAID10.

Software-RAID5 should be avoided as it is CPU intensive and there are many 
good true hardware solutions for it that are supported in Linux.


On Fri, 2 Sep 2005, Francisco Perez wrote:

> Date: Fri, 02 Sep 2005 20:24:44 -0500
> From: Francisco Perez <fperez@albrookdata.com>
> Reply-To: gentoo-amd64@lists.gentoo.org
> To: gentoo-amd64@lists.gentoo.org
> Subject: Re: [gentoo-amd64] Upgrading to Raid
> 
> Correct me if I am wrong since I have yet to have to deal with restoring 
> failed disk in an array, but in a hardware raid, with my card I would just 
> enter the card's bios after rebooting and then restore the new replacement 
> drive from the secondary image (remember I am using raid 10 with 4 disks.) 
> Is there something I'm forgetting?
>
> Frank
>
> Florian D. wrote:
>>  because there are so many people praising software-raid, you´ll probably
>>  find this story interesting, which happened to me yesterday (my system is
>>  -for the biggest part- on a raid5 partition):
>>
>>  while I emerged koffice, played some mp3´s and let matlab calculate sth.
>>  in the background, I tried to start a windows program with wine. I really
>>  shouldn´t do that, because Linux crashed and after a hard reboot it could
>>  not boot any more. It stopped during the execution of the init-scripts and
>>  i was not able to do anything, thus: 2nd hard reboot. I have another(old)
>>  gentoo installation on my computer and this time I booted into that one.
>>  By accident I realized that one of the discs of my raid system has been
>>  marked as faulty and it was syncing in the background. /proc/mdstat said
>>  that it would need 20min or so, but after 15min it said 200min! After
>>  another 10min it was sth >300min (and a lot of IO errors). So I rebooted
>>  again, this time it synced successfully in 12min. Then it was possible to
>>  boot and work with my normal system without any further difficulties or IO
>>  errors.
>>
>>  Summing up, I can say:
>>
>>  + I successfully wrecked my file system, but software raid was able to
>>  repair it
>>  - without a second Linux-installation on another partition, you´re lost
>>  - restoring of a faulty raid disk is not reliable
>>  - it seems that it is not possible to boot or work with a system, whose
>>  system disk is being restored at the same time (Linux-2.6.12.6)
>