[SATLUG] lvm2 and raid 0

Chris Lemire good_bye300 at yahoo.com
Mon Jan 7 15:53:40 CST 2008


It should provide me with enough performance because that's where all my installed applications will be and virtual appliances. I dont want to put /home in raid 0 because that's where the files are such as pictures and things that can't be replaced. I will also have quake 4 installed onto the / partition with raid 0. I wonder if that will increase my performance with it. Even with 2x core overclocked cpu, 2 gb dual channel memory, sata2 drives, and a 8800 gts 320 mb, I can't run Quake 4 in Linux at full settings. I can run it at full settings at 1280x1024. I haven't tried to see if I could do 1600x1200 with overclocking the gpu using coolbits and running the game on a raid 0 device.

Brad Knowles <brad at shub-internet.org> wrote:
  It was John Pappas who left me with the impression that someone might 
mistake his statements to conclude that striping had redundancy.

I'm not saying that this is what John meant, either -- I think he was 
more focussed on the issue of how many disks are required to implement 
shat features. It's just that I felt he may have left a not-entirely- 
correct impression, which I wanted to make sure that we were all clear 
on.


There is nothing like RAID-5 that doesn't require at least three 
disks. You can do mirroring (RAID-1), but that's not really anything 
like RAID-5.


If you want to use RAID-0 for performance, I would encourage you to 
look at your actual performance baseline and see if putting / on 
RAID-0 is going to help. If your performance bottleneck is /home, then 
putting / on RAID-0 may not buy you much additional performance, while 
potentially causing a significant reduction in reliability.

You may also want to look at separating /var from everything else on / 
and putting it on a device that may have higher performance but lower 
reliability. If you were to just lose just /var instead of the entire 
root filesystem, that may be a lot less painful.

But you won't know where it makes the most sense to put what type of 
RAID configuration without looking at some sort of bottleneck analysis 
and performance baseline.

-- 
Brad Knowles 


Sent from my iPhone

On Jan 7, 2008, at 2:47 PM, Chris Lemire wrote:

> I don't know why people are thinking that I said striping has 
> redundancy or raid and lvm are the same. I never said either. I know 
> raid 5 requires 3 drives. I was wondering if it is possible to have 
> something similar without 3 drivers. raid 5 offers redundancy and 
> striping. I've decided to install FC8 without LVM and use software 
> RAID only. I have 2 320 gb sata2 drives. Here's what I've decided on.
> /boot in raid 1, / in raid 0, /home in raid 1. As soon as / fails, I 
> don't lose anything important, and I can just install something 
> newer than FC8 by the time it does. And swap doesn't need to be in 
> RAID. I'll just give each swap device the same priority in the /etc/ 
> fstab for striping.
>
> Brad Knowles 
wrote: On 1/7/08, John Pappas 
> quoted Chris Lemire :
>
>>> Having redundancy and striping requires at least 3 hard disks, 
>>> right?
>>
>> Beyond Daniel's input, Striping requires 2,
>
> A minor technical nit -- striping does not have any redundancy. It
> does still require a minimum of two disks, however.
>
> -- 
> Brad Knowles
>
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