Re: [TCLUG:22757] Raid and other storage stories

[dopp@acm.cs.umn.edu]

WOW!  This seems exactly like the AIX LVM.  Can you resize the partitions
whever you want without loosing data and without rebooting?  If not, then
I'd say this is more like SGIs XLV LVM which is just basically software
RAID.

Gabe
> 
> I've used, and love, LVM in both the development kernel, 2.4, and the
> stable kernel+patches, 2.2.17 + rawio + lvm 0.8final.  It's a
> WONDERFUL tool that solves all of my partitioning problems and
> desires.  Let's say you have one harddrive, but you'd like to have a
> separate parition for a number of mount points in your filesystem:
> 
>     ------------------------------
>     Desired             Partition
>     ------------------------------
>     /                   /dev/sda3
>     /boot               /dev/sda1
>     swap                /dev/sda2
>     ------------------------------
>     (LVM Partitions     /dev/sda4)
>     ------------------------------
>     /usr                /dev/vg01/lv_usr
>     /home               /dev/vg01/lv_home
>     /home/cvs           /dev/vg01/lv_home_cvs
>     /home/ftp           /dev/vg01/lv_home_ftp
>     /tmp                /dev/vg01/lv_tmp
>     /usr/src            /dev/vg01/lv_src
>     /usr/local          /dev/vg01/lv_local
>     /var                /dev/vg01/lv_var
>     /var/cache/cdiso    /dev/vg01/lv_var_cache_cdiso
> 
> This may seem like overkill for one drive, but if you think about it,
> the directories that contain files that are changing often (relatively
> speaking) should be separated from those that are not to combat the
> fragmentation that will obviously happen.  /usr/src, /usr/local,
> /home, /home/cvs, /var, /tmp are quite dynamic, but /usr, /, and /boot
> don't change that often.  Why subject these the /usr to
> fragmentation from compiling your kernels in /usr/src, for example.
> 
> The other great thing about LVM is that it doesn't matter WHAT
> filesystem you use on each Logical Volume parition.  The LV acts as if
> it were any other system parition; it is a block device that you have
> complete control over.
> 
> Also notice that I don't have to worry about logical partitions on the
> disk.
> 
> Now, if I want to add a new disk and, say, migrate /home/ftp to it, I
> can do so simply by paritioning that ENTIRE disk as a physical volume.
> I can skip the fdisk step entirely, allowing me to use the otherwise
> reserved administration space on the disk.  I can add that physical
> volume to volume group vg01 if I desire, or start an entirely new VG.
> 
> You don't necessarily have to understand the entire LVM system to use
> it in a practical sense, but it is quite powerful and quite flexible.
> Just like ReiserFS, LVM *can* be installed on the root parition.
> 
> All in all, LVM is a VERY nice complimentary service to any disk
> management solution.  RAID, "RAID-less" striping, loop back devices,
> etc.  It's all very very cool. ;-)
> 
> -- 
>   Chad "^chewie, gunnarr" Walstrom <chewie@wookimus.net>
>               http://www.wookimus.net/


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-- 
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Gabe Turner				       |  	   X-President,
UNIX Systems Administrator,		       | Assoc. for Computing Machinery
U of M Supercomputing Institute for	       |    Univerisity of Minnesota
Digital Simulation and Advanced Computation    |       dopp@acm.cs.umn.edu

"YOU _GAVE_AWAY_ $47 MILLION DOLLARS??  You fat, bloated eediot!"
						- Ren Hoek in "Stimpy's Big Day"
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