Another note with regards to LVM: with our infrastructure we did some basic IOZone and bonnie++ tests and discovered that use of LVM causes up to a 10% performance hit for I/O operations in relation to using a native partition table.  This convenience did not seem to be worth the hit in performance we found.

-Aaron


On Mar 10, 2011, at 1:48 PM, Konstantin Olchanski wrote:

> On Thu, Mar 10, 2011 at 05:35:30AM -0500, Robert P. J. Day wrote:
>> 
>>  first question -- is there any sane reason not to use LVM these
>> days?  the manual opens (predictably) with showing the student how to
>> allocate fixed partitions during the install, and leaves LVM setup for
>> later in the week as an "advanced" topic.  i see it the other way
>> around -- LVM should be the norm nowadays.
>> 
> 
> 
> No reason to use LVM. The traditional "md" software raid is much simpler
> and easier to manage (only one tool to learn - mdadm, compared
> to the 100 lvm management programs). Historically, LVM is a knock-off
> of XLV which was the companion partitionning tool to SGI's XFS filesystem.
> 
> 
>>  thoughts?  i'll always allocate /boot as a regular partition but
>> unless there are compelling reasons not to, i always recommend LVM as
>> the standard.
> 
> 
> Your /boot partition has to be mirrored across both of your system disks.
> If it's only on one disk and it fails, you have an unbootable machine,
> regardless of what tool you used (lvm or md).
> 
> With "md" it is very simple, /dev/md0 is the system partition mirrored
> across /dev/sda1 and /dev/sdb1, there is no need for separate /boot
> partition, GRUB happily installs on both /dev/sda and /dev/sdb, and
> your machine happily boots if either disk explodes.
> 
> To do the same with LVM, you probably have to read a book and take
> an advanced sysadmin class; and forget about getting it to actually
> work without the help of this mailing list.
> 
> 
> -- 
> Konstantin Olchanski
> Data Acquisition Systems: The Bytes Must Flow!
> Email: olchansk-at-triumf-dot-ca
> Snail mail: 4004 Wesbrook Mall, TRIUMF, Vancouver, B.C., V6T 2A3, Canada