From: Mircea Ciocan <mirceac@interplus.ro>
To: "Rechenberg, Andrew" <ARechenberg@shermanfinancialgroup.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: Please help with a special RAID 1 setup
Date: Wed, 07 Jan 2004 22:17:13 +0200 [thread overview]
Message-ID: <3FFC6949.1060101@interplus.ro> (raw)
In-Reply-To: <8075D5C3061B9441944E137377645118012F02@cinshrexc03.shermfin.com>
Rechenberg, Andrew wrote:
>
>
>
>
>>-----Original Message-----
>>From: linux-raid-owner@vger.kernel.org
>>[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Cress, Andrew R
>>Sent: Wednesday, January 07, 2004 9:48 AM
>>To: Catalin BOIE; Mircea Ciocan
>>Cc: linux-raid@vger.kernel.org
>>Subject: RE: Please help with a special RAID 1 setup
>>
>>
>>Note that RAID-1 will only ever have a maximum of 2 active disks.
>>
>>
>
>I don't believe that the above is a correct statement. Linux software
>RAID1 will allow mirroring across more than 2 devices:
>
>[root@cinshrlnxlap01 ~]# cat /proc/mdstat
>Personalities : [raid1]
>read_ahead 1024 sectors
>md2 : active raid1 [dev 01:02][2] [dev 01:01][1] [dev 01:00][0]
> 4032 blocks [3/3] [UUU]
>
>
>
This is a refershing info, depressing is the fact that a slice can't
be added unobrtusively ( sp ?), I'll try Luca's solution first than
scratch & rebuild if this will be a resounding failure ;).
[SNIP]
>We had a "triple" mirror sofware RAID setup on a box as a "poor man's
>snapshot" before we started using LVM. We triple mirrored and then
>broke one mirror to backup and then added the removed disk back into the
>array and re-synched. LVM snapshots are much more elegant and LVM
>provides more functionality such as extended volumes when you want to
>add more space. You have to be careful using LVM because as of 2.4.18
>there was a Linux VM bug that would not allow snapshotting with greater
>than about 6GB of system RAM.
>
>However, I would recommend recreating the filesystem on top of LVM and
>using snapshots to accomplish what you want. We use LVM on top of SW
>RAID with great success.
>
>
>
Ha, so I'm not the only one crazy enough to propose such a solution,
I'm happy that I'm not alone :), did it worked ??
I belive that was designed and initialised from the first time as a 3
slice raid, the 3rd slice wasn't aded as an aftertought ??
The raid boxes have 4GiB RAM so is not a problem, BTW to you have a
pointer for starting the RTFM about that LVM and especially those
snapshots, is there a posibility to to save the inital setup with 2
slices or everything has to be destroyed and recreated again???
Best regards,
Mircea
next prev parent reply other threads:[~2004-01-07 20:17 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-07 18:14 Please help with a special RAID 1 setup Rechenberg, Andrew
2004-01-07 18:59 ` Michael
2004-01-07 20:17 ` Mircea Ciocan [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-01-13 20:50 linux
2004-01-07 19:28 Cress, Andrew R
2004-01-07 20:21 ` Mircea Ciocan
2004-01-07 15:32 Dr. Greg Wettstein
2004-01-07 14:48 Cress, Andrew R
2004-01-07 15:33 ` Mircea Ciocan
2004-01-07 16:09 ` Luca Berra
2004-01-07 10:16 Mircea Ciocan
2004-01-07 12:20 ` Catalin BOIE
2004-01-07 13:23 ` Mircea Ciocan
2004-01-07 13:31 ` Catalin BOIE
2004-01-07 13:47 ` Catalin BOIE
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