Re: Re: [gentoo-user] raid/partition question

Thank you very much.  I'll need to go back and reread this and digest it some more.  I hadn't thought of doing multiple RAID types on the drives.  I have two and did RAID1 for /boot and was going to RAID1 the rest.  However, I really want RAID0 for speed and capacity on some file systems.  The swap comment is interesting, too.  I have two small partitons for swap - one on each drive and I was going to parallel them per one of  DRobbins articles.



>
> From: "Boyd Stephen Smith Jr." <bss03@××××××××××.com>
> Date: 2006/02/20 Mon PM 01:30:59 EST
> To: gentoo-user@l.g.o
> Subject: Re: [gentoo-user] raid/partition question
>
> On Monday 20 February 2006 11:51, brettholcomb@×××××××××.net wrote about
> 'Re: Re: [gentoo-user] raid/partition question':
> > As an extension of this question since I'm working on setting up a
> > system now.
> >
>
> 3. Neither.  See below.  First a discussion of the two options.
>
> 1. Is fine, but it forces you to choose a single raid level for all your
> data.  I like raid 0 for filesystems that are used a lot, but can easily
> be reconstructed given time (/usr) and especially filesystems that don't
> need to be reconstructed (/var/tmp), raid 5 or 6 for large filesystems
> that I don't want to lose (/home, particularly), and raid 1 for critical,
> but small, filesystems (/boot, maybe).
>
> 2. Is a little silly, since LVM is designed so that you can treat multiple
> pvs as a single pool of data OR you can allocate from a certain pv --
> whatever suits the task at hand.  So, it rarely makes sense to have
> multiple volume groups; you'd only do this when you want a fault-tolerant
> "air-gap" between two filesystems.
>
> Failure of a single pv in a vg will require some damage control, maybe a
> little, maybe a lot, but having production encounter any problems just
> because development had a disk go bad is unacceptable is many
> environments.  So, you have a strong argument for separate vgs there.
>
> 3. My approach: While I don't use EVMS (the LVM tools are fine with me, at
> least for now) I have a software raid 0 and a hw raid 5 as separate pvs in
> a single vg.  I create and expand lvs on the pv that suits the data.  I
> also have a separate (not under lvm) hw raid 0 for swap and hw raid 6 for
> boot.  I may migrate my swap to LVM in the near future; during my initial
> setup, I feared it was unsafe.  Recent experience tells me that's (most
> likely) not the case.
>
> For the uninitiated, you can specify the pv to place lv data on like so:
> lvcreate -L <size> -n <name> <vg> <pv>
> lvresize -L <size> <vg>/<lv> <pv>
> The second command only affect where new extents are allocated, it will not
> move old extents; use pvmove for that.
>
> --
> Boyd Stephen Smith Jr.
> bss03@××××××××××.com
> ICQ: 514984 YM/AIM: DaTwinkDaddy
> --
> gentoo-user@g.o mailing list
>
>

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