<p><br />
----- Message from rwalker@medallion.com ---------<br />
Date: Fri, 19 Oct 2007 09:53:20 -0400<br />
From: "Ross S. W. Walker" <rwalker@medallion.com><br />
Reply-To: "Ross S. W. Walker" <rwalker@medallion.com><br />
Subject: RE: [DRBD-user] drbd implementation question<br />
To: kbyrd-drbd@memcpy.com, drbd-user@lists.linbit.com<br />
<br />
<br />
> Kelly Byrd wrote:<br />
>><br />
>> On Thu, 18 Oct 2007 18:48:56 +0200, "Rudi Ahlers"<br />
>> <Rudi@SoftDux.com> wrote:<br />
>> > Hi all<br />
>> ><br />
>> > I'm new to drbd and have some questions, hoping someone<br />
>> could help me.<br />
>> I'd<br />
>> > like to use software RAID & LVM to make it easier to upgrade
in the<br />
>> future.<br />
>> ><br />
>><br />
>> > how do I manage such a setup?<br />
>> > Do I first setup the RAID, then the LVM volumes and the drbd?<br
/>
>> > Can I install & setup drbd on partitions with existing
data?<br />
>> ><br />
>><br />
>> What are you looking for in the end? One big replicated chunk<br />
>> of space? Do you need smaller granularity? For the local<br />
>> RAID, what are the requirements there? RAID0? RAID5? RAID1?<br />
>><br />
>> If you're going to run raid and lvm underneath drbd, I'm not<br />
>> sure how you'll keep existing data. Wouldn't creating LVMs on<br />
>> top of an existing partition with data in it destroy that<br />
>> filesystem?<br />
>><br />
>> I'm pretty sure you can't directly create a drbd with existing<br />
>> data, drbd is a block device, so it would run underneath a<br />
>> filesystem. If you had a filesystem with data in it already,<br />
>> making a drbd out of that space would screw up the filesystem<br />
>> and the data. Just like when you create a RAID1 from existing<br />
>> data, you copy the data into the RAID1.<br />
><br />
> Create the RAID, whether it is HW or SW.<br />
><br />
> Create a LVM VG out of the RAID array(s).<br />
><br />
> Create LVM LVs out of the VG.<br />
><br />
> You can create a drbd volume after the fact, you just CANNOT<br />
> create it with the meta-data on that volume you have to locate<br />
> the meta-data on a separate volume.<br />
><br />
> I prefer to locate the meta-data separately anyways, I create<br />
> a separate LV for drbd meta-data, and do drbd per-LV instead<br />
> of per RAID array.<br />
><br />
> -Ross<br />
><br />
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----- End message from rwalker@medallion.com -----<br />
<br />
</p><p></p><p>Thanx for the input, Ross & Kelly</p><p></p><p>Kelly, to
answer your questions:</p><ul><li>I'd use any level of RAID, depending on the
application / use of the servers</li><li>I really only want to use LVM to make
growing the partition size easier. But from what I can gather, I don't need to
use LVM, is that so?</li></ul><p>Ross, I do have a question for you, on your
suggestion.</p><p>Let's say I have 2x 160GB HDD's, which I mirror RAID, leaving
me with /dev/md1 (100MB) & /dev/md1 (158GB - rest = swap), now I create my
LV volumes, / (/dev/mapper/system-root) being say 8GB, /home
(/dev/mapper/system-home) being 100GB, and /opt (/dev/mapper/system-opt) 50GB.
When I setup the partitions like this when I install the machine, all the
relevant info is installed, so I need to temporarely move the info from /home
& /opt somewhere else if I want to sync those to patitions?</p><p>And, what
do I add to my drbd.conf file for those parititions? I have tried
/dev/mapper/system-home, but it doesn't seem to work. How do I use LVM VG's with
DRBD?</p><p>
-- <br />
<br />
Kind Regards<br />
Rudi Ahlers<br />
SoftDux CEO<br />
<br />
Website: <a target="_blank"
href="http://www.softdux.com/">http://www.SoftDux.com</a><br />
Support: <a target="_blank"
href="http://support.softdux.com/">http://Support.SoftDux.com</a><br />
Cellphone: 082 554 7532<br />
<br />
</p>