Insight on partitioning a LAMP Server design issue

[Stephen Goldman]

Hello Blu,
    Request insight on partitioning a new "LAMP" server with two partitions.
    Seeking input from others more experienced than me.. thanks,  
    Are there any posted guidlines for best performance. Wish to provide best product
   
    The device is a brand new Dell server with:
    /dev/sda    raid one 160 G
    /dev/sdb    raid five 270G

    32 G phyiscal ram
    RHEL 5.3

    My plan was to partition /dev/sda as follows:

    /            25  G
    /            20  G swap
    / var       25 G
    /tmp      20  G
    /home   remainer

    /dev/sdb

    /data    =  270 G

    I am provisioning the machine for others who will configure ,Apache and Mysql


    I suggested they redirect the Apache root folders and Mysql db to run on /dev/sdb.
    The researcher who is creating the site states he has only worked with both services when configured inside /var.
    Linmited experience.

    I know the Apache can be redirected .. but no sure of how the redirect Mysql   to live on       /dev/sdb --
   
    Questions:
    Does the partitioning scheme make sense ..
    Is there performance gains running the services on the partitiion /dev/sdb
    Is it difficult to redirect the services on /dev/sdb ?
    Is it easier to place /var  on  /dev/sdb  size it to the whole partition?
   
    /home does not need to be  70 G .. but the space  is there //

    Thanks for you input,

Stephen

   













Stephen Goldman
Systems Administrator
Department of Biology
Massachusetts Institute of Technology
31 Ames Street, Cambridge, MA 02139
sgoldman@..., [phone]
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[Jerry Feldman-2]

I have no issues with your partitioning scheme, but a few questions. Why
have /dev/sda RAID 1 and /dev/sdb RAID 5? I thought that a single RAID
volume required 2 separate physical volumes volumes.
Secondly, I would probably want to use LVM to give you greater
flexibility so you can resize and move things around.



On 10/31/2009 07:01 AM, Stephen Goldman wrote:

> Hello Blu,
>     Request insight on partitioning a new "LAMP" server with two partitions.
>     Seeking input from others more experienced than me.. thanks,  
>     Are there any posted guidlines for best performance. Wish to provide best product
>    
>     The device is a brand new Dell server with:
>     /dev/sda    raid one 160 G
>     /dev/sdb    raid five 270G
>
>     32 G phyiscal ram
>     RHEL 5.3
>
>     My plan was to partition /dev/sda as follows:
>
>     /            25  G
>     /            20  G swap
>     / var       25 G
>     /tmp      20  G
>     /home   remainer
>
>     /dev/sdb
>
>     /data    =  270 G
>
>     I am provisioning the machine for others who will configure ,Apache and Mysql
>
>
>     I suggested they redirect the Apache root folders and Mysql db to run on /dev/sdb.
>     The researcher who is creating the site states he has only worked with both services when configured inside /var.
>     Linmited experience.
>
>     I know the Apache can be redirected .. but no sure of how the redirect Mysql   to live on       /dev/sdb --
>    
>     Questions:
>     Does the partitioning scheme make sense ..
>     Is there performance gains running the services on the partitiion /dev/sdb
>     Is it difficult to redirect the services on /dev/sdb ?
>     Is it easier to place /var  on  /dev/sdb  size it to the whole partition?
>    
>     /home does not need to be  70 G .. but the space  is there //
>
>     Thanks for you input,
>
>  

--
Jerry Feldman <gaf@...>
Boston Linux and Unix
PGP key id: 537C5846
PGP Key fingerprint: 3D1B 8377 A3C0 A5F2 ECBB  CA3B 4607 4319 537C 5846



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[Dan Ritter-2]

On Sat, Oct 31, 2009 at 07:35:04AM -0400, Jerry Feldman wrote:
> I have no issues with your partitioning scheme, but a few questions. Why
> have /dev/sda RAID 1 and /dev/sdb RAID 5? I thought that a single RAID
> volume required 2 separate physical volumes volumes.
> Secondly, I would probably want to use LVM to give you greater
> flexibility so you can resize and move things around.

My assumption was that /dev/sda is a RAID 1 volume presented by
his hardware RAID controller, and was 2 disks ganged together,
and that /dev/sdb is a RAID5 volume, similarly presented,
probably 3-5 disks ganged together.

I generally think RAID 5 is a poor compromise.

-dsr-


--
http://tao.merseine.nu/~dsr/eula.html is hereby incorporated by reference.
You can't defend freedom by getting rid of it.
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[Tom Metro-16]

Stephen Goldman wrote:
>     The device is a brand new Dell server with:
>     /dev/sda    raid one 160 G
>     /dev/sdb    raid five 270G
...
>     There is a total of six drives :
>         Raid one for the OS
>         Raid five for the data & db

So really you're talking about /dev/md0 .. /dev/md4 for the first set
(given your proposed list of partitions), and /dev/md5 for the second.
As Jerry suggested, using LVM would let you have just /dev/md0 and
/dev/md1, with LVM used to split up /dev/md0 into the collection of
partitions you desire. See:

http://www.tldp.org/HOWTO/Software-RAID-HOWTO-11.html


>     32 G phyiscal ram
>     /            20  G swap

Traditionally swap gets set to a multiplier of RAM, but with 32 GB of
RAM, I don't know if this wisdom still holds up. I'd recommend doing
some research.


>     My plan was to partition [the RAID 1 set] as follows:
>
>     /            25  G
>     / var       25 G
>     /tmp      20  G
>     /home   remainer

I've set up systems with similar capacities (though with /var and /home
included with root), and inevitably ended up moving all or most of /var
to a second disk (or array), along with /home, and having to spend time
managing space on root. It doesn't take long for a modern system to fill
up a 25 GB root.

Your primary objective here should be just to keep what is needed to
boot the system on the RAID 1 set, with a secondary objective of keeping
/tmp and other variable partitions from crowding out root.

You can accomplish that by sticking with your 20 GB partition for /tmp,
putting /var and /home on the RAID 5 set, and letting root take up the
rest of the RAID 1 set.


> I know the Apache can be redirected ..
> Please confirm that Mysql can be configured to live on the [other RAID set]

Yes, trivial. Either via symlink, mount point, or by modifying the
setting in /etc/mysql/my.cnf.


> Is there performance gains running the services on the partitiion /dev/sdb

If you have two applications that make heavy use of the disk, it's
common to distribute them among separate disks. If MySQL, for example,
is going to see a lot of activity, while having more modest capacity
requirements compared to Apache, you could put its data files on the
RAID 1 set. Given that you'll have two storage systems with likely
different read and write performance, the ideal approach would be to
benchmark your usage to see what works best.

  -Tom

--
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/
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[Dan Ritter-2]

On Sat, Oct 31, 2009 at 12:20:26PM -0400, Tom Metro wrote:

> Stephen Goldman wrote:
> >     The device is a brand new Dell server with:
> >     /dev/sda    raid one 160 G
> >     /dev/sdb    raid five 270G
> ...
> >     There is a total of six drives :
> >         Raid one for the OS
> >         Raid five for the data & db
>
> So really you're talking about /dev/md0 .. /dev/md4 for the first set
> (given your proposed list of partitions), and /dev/md5 for the second.

I don't think so. I think that the hardware RAID is taking
physical disks 0 and 1 and presenting them as sda, and physical
disks 2,3,4,5 and presenting them as sdb.

LVM may be a win for him, long term. I generally agree with the
rest of what you write.

-dsr-


--
http://tao.merseine.nu/~dsr/eula.html is hereby incorporated by reference.
You can't defend freedom by getting rid of it.
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[Stephen Goldman]

Thank you All,
Stephen



----- Original Message -----
From: "Dan Ritter" <dsr@...>
To: "Tom Metro" <tmetro-blu@...>
Cc: "Stephen Goldman" <sgoldman@...>; "L-blu" <discuss@...>
Sent: Saturday, October 31, 2009 12:26 PM
Subject: Re: Insight on partitioning a LAMP Server design issue

> On Sat, Oct 31, 2009 at 12:20:26PM -0400, Tom Metro wrote:
>> Stephen Goldman wrote:
>> >     The device is a brand new Dell server with:
>> >     /dev/sda    raid one 160 G
>> >     /dev/sdb    raid five 270G
>> ...
>> >     There is a total of six drives :
>> >         Raid one for the OS
>> >         Raid five for the data & db
>>
>> So really you're talking about /dev/md0 .. /dev/md4 for the first set
>> (given your proposed list of partitions), and /dev/md5 for the second.
>
> I don't think so. I think that the hardware RAID is taking
> physical disks 0 and 1 and presenting them as sda, and physical
> disks 2,3,4,5 and presenting them as sdb.
>
> LVM may be a win for him, long term. I generally agree with the
> rest of what you write.
>
> -dsr-
>
>
> --
> http://tao.merseine.nu/~dsr/eula.html is hereby incorporated by reference.
> You can't defend freedom by getting rid of it.
>

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