Re: IO rate for U320 SCSI 15K RPM Hard Drive

  • From: "goran bogdanovic" <goran00@xxxxxxxxx>
  • To: cika.lale@xxxxxxxxxxxxxx
  • Date: Thu, 12 Oct 2006 23:23:11 +0200

Hi Lale,

To calculate the sequential IO you can use the follwing:

seconds per IO=(transfer time) + (track-to-track seek time) + (avg.
rotational latency)

(assuming that we have track-to-track seek time between each IO)

IOPS=1/(seconds per IO)

for random IO  you can calculate

seconds per IO= (transfer time) + (random seek time) + (avg. rotational

(assming we have random seek between each IO)

IOPS=1/(seconds per IO)

The transfer time, track-to-track seek time, avg. rotational latency, random
seek time you can find in HDD spec.

For random seek time we can assume that we have mixture of reads and writes
and take the avg. of disc spec. "avg. seek time, read" and "avg. seek time,

Since most IO operations done by oracle are random in nature, you should try
sizing your system not to the calculated max. random access performance but
to operate at around 75% of max. performance. The reason for this is that
the IO response time increases as you reach the max. capacity of the disk
drive and the queue length can increase greatly.

Also, take into consideration that in addition to disk drive latencies, the
latencies of IO controller have to be taken into the account too.



On 9/28/06, Michael Erwin <michael.erwin@xxxxxxxxxx> wrote:

Hi Lale,

One would expect to find it here:

Nothing really available on their site...

However, estimate IOPS is relatively easy with

  Spindle IOPS = ((RPM/60)/3)*2

Or at least ~167 8k IOPS per spindle

To figure out User Data Transfer rates, use the following:

UDT=(Spindle Speed / 60 * Sectors Per Track * Bits per Sector * 8) /

Bits Per Sector as defined by HP can be here:

So BPS=512

The other two number we need is the platters used in this 146GB drive and
the physical platter size (3.5", 2.5", 1", and I would assume 3.5") to
determine an areal density or at least GB/Platter density to determine the
inner & outer range of UDT. It will be a wide range considering Zone Bit
Recording (ZBR)

BTW, the whole U320 MB/Sec transfer is a U320 SCSI transfer rate and not
the user data transfer rate for the drive itself.

*Michael Erwin* Hotsos Enterprises, Ltd. Hotsos Symposium 2007 / March 4-8 Visit<http://exchweb/bin/redir.asp?URL=>for curriculum and schedule details...

*From:* oracle-l-bounce@xxxxxxxxxxxxx on behalf of lale obradovic
*Sent:* Thu 9/28/2006 12:19 PM
*To:* oracle-l
*Subject:* IO rate for U320 SCSI 15K RPM Hard Drive

Hi All,

Does anyone have some information of expected IO rate (IOPS and/or MBPS)
for U320 SCSI 15K RPM Hard Drive (HP 146GB U320 15K Universal HDD)?



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