[CentOS] Advice on partitioning a Dell MD1200 disk array

Tony Molloy tony.molloy at ul.ie
Tue Sep 4 14:07:31 EDT 2012


On Tuesday 04 September 2012 12:44:26 Götz Reinicke wrote:
> Hi Tony,
> 
> because I suggest just something very general I post off list :)
> 
> From my POV as I'm currently facing similar setups with different
> hardware rolling back from fine granular setups to simple 'bigger'
>  less complex configurations. (we do have 6 iscsi storages from 2TB
>  (sun ZFS) up to 32 TB)
> 
> 	keep it small and simple! :)
> 
> I think you are very familiar with the general problems of big HW
>  raids and big filesystems like rebuild or check times, but
>  splitting up and adding more complex layers like multiple raids
>  joining in lvm etc. makes debugging and general handling very
>  hard.
> 
> On the other hand, I checked and read a lot about filesystems the
>  last days being faced with serving user windows samba profiles
>  with lot of small files and big video/audio data etc.
> 
> Long story short:
> 
> I usually do one raidvolume per hardware raid box; e.g. we use
>  16*1TB drives. Raid6 or Raid5 with spare. I did not notice big
>  performance differences.
> 
> I use LVM to make partitions or I prefer using just one big
>  partition.
> 
> I tried xfs and ext4 and will go with ext4 as some test went better
>  for my setup and from what I read it looks not bad :)
> 
> I think you can combine block level devices (like multiple raid
>  boxes) by LVM into one bigger LV.
> 
> And last but not least: The CPU/RAM/Network of the host serving the
> files is also very important! :)
> 
> I noticed, that the same iscsi storage got about 70MB/s on a new
>  server (xeon multicore), while on the old fileserver it just got
>  up to 40MB/s.
> 
> 
> 
> 	my2cents :) regards . Götz
> 
> 
> 
> May be worth reading:
> 
> http://www.techforce.com.br/news/linux_blog/lvm_raid_xfs_ext3_tunin
> g_for_small_files_parallel_i_o_on_debian#.UEPSI1RqYso
> 
> http://monolight.cc/2011/02/linux-filesystems-small-file-performanc
> e-on-hdds/
> 
> http://unix.stackexchange.com/questions/28756/what-is-the-most-high
> -performance-linux-filesystem-for-storing-a-lot-of-small-fi
> 
> https://wiki.archlinux.org/index.php/Ext3
> 
> https://wiki.archlinux.org/index.php/Ext4#Tips_and_tricks
> 
> Am 04.09.12 13:10, schrieb Tony Molloy:
> > Hi,
> >
> > I've just got possession of a Dell PE R720 with 2 MD1200 disk
> > enclosures.
> >
> > Both MD1200 are fully populated with 12 x 3 TB disks
> >
> > The system will basically be a student file-server running CentOS
> > 6.x serving various size files from small c programs to multi
> > gigabyte audio and video files over GB ethernet.
> >
> > The first MD1200 will be configured as the NFS disk. The
> > requirements are for 6 fixed equally sized partitions, one for
> > each cohort of students. For this I was thinking of splitting the
> > MD1200 into 2 RAID5 arrays with a hot spare each. Then
> > partitioning each into 3 ext4 partitions.
> >
> > The second MD1200 will be used to backup the first, using
> > BackupPC and for other storage purposes.
> >
> > As I won't know the storage requirements for the "backup
> > partition" and they will probably change over time anyway. I was
> > thinking of using LVM for it. So how to partition the MD1200 for
> > LVM. I don't want to put all 12 disks in  a RAID5 and put a LVM
> > volume on it. Can I split it into 2 RAID5 and have a LVM volume
> > spanning both.
> >
> > Any suggestions.
> >
> > Just remember I'm due to retire at the end of this month so this
> > will be my last big job for the Dept. And due to financial
> > constraints I will not be replaced. So I will be handing this
> > machine over to a co- worker who is basically a Windoze admin
> > with only a basic knowledge of Linux so nothing too fancy.  ;-)
> >
> > Thanks,
> >
> > Tony
> >
> >
> > --
> >
> > Tony Molloy
> >
> > CTO, Dept. of Comp. Sci.
> > University of Limerick
> > Limerick.
> > Ireland
> > _______________________________________________
> > CentOS mailing list
> > CentOS at centos.org
> > http://lists.centos.org/mailman/listinfo/centos
> 


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