I'm trying to understand which value to use in creating primary
partition in my win2003 server to use with sql 2005.

Using diskpart, this seems the best

"create partition primary align=64"

but I also found this version:

"create partition primary align=1024"

please can you explain the differences and the best choice ?

Thanks.

This value is really only relevant on abstracted storage (SANs). Since the
SAN has its own stripe size, it makes sense to align the OS allocation units
with the underlying stripe boundaries. This prevents one I/O request from
creating two IO requests inside the storage system, leading to severely
degraded performance.

Most storage systems use 64 or 128 K stripes. Windows 2003, by default uses
a 63K MBR offset for all partitions, which messes up ANY abstract storage
system.

1024 is very much overkill. As long as you are at some multiple of 128,
you will be safe for almost any storage platform.

--
Geoff N. Hiten
Principal SQL Infrastructure Consultant
Microsoft SQL Server MVP




"joker197cinque" <joker197cinque (AT) gmail (DOT) com> wrote

I read that, up to Win server 2003, disk alignment is mandatory using
standard SCSI HDs or LUNs in a SAN.

Sorry but I am not so good in english: I did an alignment of 64 .. do
you think it is a bad value ? Is 128 better ?

Thanks.

64 should be fine.

--
Geoff N. Hiten
Principal SQL Infrastructure Consultant
Microsoft SQL Server MVP


"joker197cinque" <joker197cinque (AT) gmail (DOT) com> wrote

I read that, up to Win server 2003, disk alignment is mandatory using
standard SCSI HDs or LUNs in a SAN.

Sorry but I am not so good in english: I did an alignment of 64 .. do
you think it is a bad value ? Is 128 better ?

Thanks.

That is not true in all cases. Some disk arrays are insensitive to the
offset value (HP EVA for instance). However, since it doesn't hurt to have
the offset value as multiples of 64KB, you might as well set that as a
standard for any new storage provision. Now, for existing storage, you should
do some tests to see if it really matters because the effort to re-align the
disk offsets can be quite expensive in terms of schedule, manpower, down
time, etc.

Linchi

"joker197cinque" wrote:

On 31 Lug, 00:46, Linchi Shea <LinchiS... (AT) discussions (DOT) microsoft.com>
wrote:

It doesn't hurt ?

I read that it not only does not hurt butit gives a performance boost
up to 30% in some cases, so I would not speak in terms of "it doesn't
hurt". But probably I miss something ...

It depends on the underlying abstraction mechanism the array uses.

That and how much Magic SAN Dust(tm) the manufacturer sprinkles inside the
box.

--
Geoff N. Hiten
Principal SQL Infrastructure Consultant
Microsoft SQL Server MVP




"joker197cinque" <joker197cinque (AT) gmail (DOT) com> wrote

I think you mis-read me. I said, it doesn't hurt to have the offset value as
multiples of 64KB. That means, if you set the offset to a multiple of 64KB,
evne if it does not help, it won't degrade the performance since any multiple
of 64KB is considered aligned.

Now, you seem to assume that it'll always boost the performance. The fact is
that it does NOT always boost the performance to 'align' the disk offset. For
instance, on a HP EVA you probably won't see any difference one way or
another.

Linchi

"joker197cinque" wrote: