[prev in list] [next in list] [prev in thread] [next in thread] 

List:       centos
Subject:    Re: [CentOS] Seeking pointers to info about LVM migration
From:       Johnny Hughes <mailing-lists () hughesjr ! com>
Date:       2007-07-07 13:31:06
Message-ID: 468F959A.1010206 () hughesjr ! com
[Download RAW message or body]

[Attachment #2 (multipart/signed)]


Bart Schaefer wrote:
> We have a large MySQL database currently running on a CentOS 3.x
> server with an external SCSI RAID device.  This is currently an ext2
> filesystem because it was migrated once previously from an even older
> RedHat system.  We need to add storage capacity to this database and
> prepare for additional future growth.  One of the options under
> consideration is to move to CentOS 5 and use LVM.
> 
> Of some concern is that we run some pretty heavy-duty queries against
> this database in close to real time, so we don't want the switch to
> scalable storage to have a significant impact on read latency.
> 
> Consequently I'm looking for sources of information on two topics:
> - What kind of performance can we expect from an LVM group as compared
> to mounting the RAID array directly?

OK, the answer to this question is ...

RAID and LVM can be used together, or individually.

If you have 2 or more drives that are the same in the machine, you can
"Stripe" your LVM.  When doing this it behaves similarly to RAID0
(striping with no CRC / Redundancy).

LVM done this way is quite fast ... but obviously you would need to
provide another way to protect your data.

See this article for how to use LVM striping:

http://www.redhat.com/magazine/009jul05/features/lvm2/

http://www.tldp.org/HOWTO/html_single/LVM-HOWTO/#recipethreescsistripe

Obviously, LVM with striping is faster than a normal LVM setup.

> - What's involved in migrating our filesystem from ext2 to LVM with a
> minimum of downtime?




["signature.asc" (application/pgp-signature)]

_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos


[prev in list] [next in list] [prev in thread] [next in thread]