On Apr 24, 7:45 am, moonhkt <moon...@gmail.com> wrote:
> Hi All
> Our Existing Database need 9.11Mbit/s(base on number of read per sec).
> For next 3 year growth, we need 26.0Mbit/s.
>
> How to testing IBM Storage system can provide the enough I/O. e.g.
> DS4000
>
> moonhkt

> Hi All
> Our Existing Database need 9.11Mbit/s(base on number of read per sec).
> For next 3 year growth, we need 26.0Mbit/s.

You must be aware of 2 different kind of disk io access pattern
1) IOPS ( I/O per second ) bound - IOPS means simply how many IO
commands the system can handle.
2) Streaming ( Bandwidth ) bound - Streaming means how fast the data
can be moved between from and to the disks

In very very simple example we will use a FC hba and 4 FC disk with
the following data:
fc-hba: 2GB ( 100 MB/way ), max 100000 IOPS
fc-disk: 140 GB , 150 IOPS , 50MB max transfer rate (r/w)

As you can see that in streaming mode ( IO size around 1MB ) like for
a "dd if=/dev/rhdisk0 of=/dev/null bs=1m" that the fc-disk would
saturate the fc adapter since the FC adapter could handle only
100Mbytes but the disks could deliver 200MB.

In an IOPS bound environment ( IO high, IO size < 1k ) like for a "dd
if=/dev/rhdisk0 of=/dev/null bs=512" the disk max IOPS would be the
limiting factor. In this example the maximum transfer rate would be
about 300kbytes ! (4 Disk * 150 IOPS * 512 Bytes ) because the maximum
IOPS is 600. Looks pretty bad but if your application is doing small
IO not the maximum transfer rate is the problem but the maximum amount
of IOPS can be the problem.

So to answer your question.
Get a baseline by determing the IO pattern of your database
application.
see vmstat, iostat , nmon and other tools.

and check if the DS4000 will fullfill the requirements.

BTW:
For your 26Mbits meaning 4Mbytes/sec named requirement a 15 year old
scsi disk should be good enough ;-)

hth
Hajo