Partitions on RAID Array

We have a 12 disk 2.4TB Raid 10 Array, where we have 3 large database data
files, theres been a suggestion that we split the physical drive into 3
partitions so if we have to grow the files in future the files will stay
contiguous on the disk.. ..I'm not worried about splitting the array into
three from a size point of view we have bags of space for future growth..
..I'm aware the databases should be sized properly so they don't autogrow a
nd
that minimal fragmentation at the os level will have little to no impact on
the performance... ...however for sake of argument will splitting the RAID
array into the 3 partitions keep the database files contiguous on the disks,
and would there be any performance hit on the array by splitting it into 3
volumes?
Thanks in advance
BenI'd be inclined to not create three logical partitions. I don't have any
current empirical data to back me up on this. But I do remember a Compaq
study a few years ago on using a single partition vs. multiple logical
partitions on a physical device, and the single partition configuration came
out better performance wise. I'm not claiming that the Compaq study is still
relevant. But then I don't see any substantial benefit of creating three
logical partitions.
The practice I follow has always been: single physical device (as presented
to the OS) -> single partition -> single NTFS volume.
Do note that if you have files on the same volume, moving a file to another
place on that same volume is a filesystem metadata operation. Moving a file
across volumes, however, must move data. If you don't plan to move your
files, this is not an issue.
Linchi
"Ben UK" wrote:

> We have a 12 disk 2.4TB Raid 10 Array, where we have 3 large database data
> files, theres been a suggestion that we split the physical drive into 3
> partitions so if we have to grow the files in future the files will stay
> contiguous on the disk.. ..I'm not worried about splitting the array into
> three from a size point of view we have bags of space for future growth..
> ..I'm aware the databases should be sized properly so they don't autogrow
and
> that minimal fragmentation at the os level will have little to no impact o
n
> the performance... ...however for sake of argument will splitting the RAID
> array into the 3 partitions keep the database files contiguous on the disk
s,
> and would there be any performance hit on the array by splitting it into 3
> volumes?
> Thanks in advance
> Ben|||Hi Ben,
I tend to agree with Linchi, that splitting it up might not give you
much in term of performance. If you should gain from splitting the files
up, you should split them up on physical different spindles and best of
all on seperate disk controllers. If you go down that route, you should
at the same time add some more spindles to each array - otherwise I
don't think you'll gain anything from the change.
You can also try to look at www.storageperformance.org to see if you can
find some usefull info in there.
Regards
Steen Schlüter Persson
Database Administrator / System Administrator
Ben UK wrote:
> We have a 12 disk 2.4TB Raid 10 Array, where we have 3 large database data
> files, theres been a suggestion that we split the physical drive into 3
> partitions so if we have to grow the files in future the files will stay
> contiguous on the disk.. ..I'm not worried about splitting the array into
> three from a size point of view we have bags of space for future growth..
> ..I'm aware the databases should be sized properly so they don't autogrow
and
> that minimal fragmentation at the os level will have little to no impact o
n
> the performance... ...however for sake of argument will splitting the RAID
> array into the 3 partitions keep the database files contiguous on the disk
s,
> and would there be any performance hit on the array by splitting it into 3
> volumes?
> Thanks in advance
> Ben