[linux-lvm] How do I do RAID 4/5 *and* LVM?

[linux-lvm] How do I do RAID 4/5 *and* LVM?

[Dave Newman]

Hi --

I have four 160 GB IDE disks, and wanted to install software RAID 4/5 
*and* LVM, and wanted to ask a couple of brief questions:

a) Do I need LVM if I want to see a single partition (or can RAID do 
this for me)?

b) Do I first install RAID, then LVM?  Are there any difficulties with 
these installs?  (I have already successfully done LVM on its own)

c) Are there any reasons why I shouldn't use both RAID and LVM?

Thanks in advance,
Dave

Re: [linux-lvm] How do I do RAID 4/5 *and* LVM?

[Herman L. Knief]

Yes, create the RAID (MD) device, then layer LVM on top... Now, depeneding
on your requirements, you may not need LVM (do you want/need snapshots,
etc?)

Also, how are you connecting these disks?  How many IDE ports are you
using?  I would recommend against any sort of master/slave setup, as
you'll have difficulties with failure detection and won't get the best
throughput.

 - Herman

On Tue, 21 May 2002, Dave Newman wrote:

->Hi --
->
->I have four 160 GB IDE disks, and wanted to install software RAID 4/5
->*and* LVM, and wanted to ask a couple of brief questions:
->
->a) Do I need LVM if I want to see a single partition (or can RAID do
->this for me)?
->
->b) Do I first install RAID, then LVM?  Are there any difficulties with
->these installs?  (I have already successfully done LVM on its own)
->
->c) Are there any reasons why I shouldn't use both RAID and LVM?
->
->Thanks in advance,
->Dave
->
->
->
->_______________________________________________
->linux-lvm mailing list
->linux-lvm@sistina.com
->http://lists.sistina.com/mailman/listinfo/linux-lvm
->read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
->

Re: [linux-lvm] How do I do RAID 4/5 *and* LVM?

[Goetz Bock]

On Tue, May 21 '02 at 08:24, Dave Newman wrote:
> I have four 160 GB IDE disks, and wanted to install software RAID 4/5 
> *and* LVM, and wanted to ask a couple of brief questions:
LVM on top of MD works very well, I'm using it on all my boxes with soft
RAID. (MD == multiple discs == linux soft raid)

dooing MD on top of LVM is possible too, but makes no scense (IMHO)

OTOH if you just want one big partition (3x160GB) than there is no need
for LVM.

> a) Do I need LVM if I want to see a single partition (or can RAID do 
> this for me)?
No, MD will do

> b) Do I first install RAID, then LVM?  Are there any difficulties with 
> these installs?  (I have already successfully done LVM on its own)
yes, first RAID than LVM, no problems to be expected.
 
> c) Are there any reasons why I shouldn't use both RAID and LVM?
No

Cu,
    Goetz

Re: [linux-lvm] How do I do RAID 4/5 *and* LVM?

[Heinz J . Mauelshagen]

On Tue, May 21, 2002 at 08:29:41AM -0700, Herman L. Knief wrote:
> Yes, create the RAID (MD) device, then layer LVM on top... Now, depeneding
> on your requirements, you may not need LVM (do you want/need snapshots,
> etc?)

Well, LVM makes a lot of sense in case he changes his mind to go with a single
partition later. In that case LVM plus fs shrinkers give him much more
flexible options he doesn't have with MD alone.

> 
> Also, how are you connecting these disks?  How many IDE ports are you
> using?  I would recommend against any sort of master/slave setup, as
> you'll have difficulties with failure detection and won't get the best
> throughput.
> 
>  - Herman
> 
> On Tue, 21 May 2002, Dave Newman wrote:
> 
> ->Hi --
> ->
> ->I have four 160 GB IDE disks, and wanted to install software RAID 4/5
> ->*and* LVM, and wanted to ask a couple of brief questions:
> ->
> ->a) Do I need LVM if I want to see a single partition (or can RAID do
> ->this for me)?
> ->
> ->b) Do I first install RAID, then LVM?  Are there any difficulties with
> ->these installs?  (I have already successfully done LVM on its own)
> ->
> ->c) Are there any reasons why I shouldn't use both RAID and LVM?
> ->
> ->Thanks in advance,
> ->Dave
> ->
> ->
> ->
> ->_______________________________________________
> ->linux-lvm mailing list
> ->linux-lvm@sistina.com
> ->http://lists.sistina.com/mailman/listinfo/linux-lvm
> ->read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
> ->
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html

-- 

Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

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Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
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