topic Re: Disk thruput in Operating System - OpenVMS

Disk thruput

Wim Van den Wyngaert — Thu, 05 Feb 2004 09:04:07 GMT

I would like to measure disk thruput per disk(in MBytes), if possible split in Read and Write thruput.

I don't want a program and I don't want to depend on a product like pa. Just DCL and e.g. SDA.

How can I do that ?

Re: Disk thruput

Ian Miller. — Thu, 05 Feb 2004 09:13:10 GMT

what sort of disks? If an HSx controller is involved then they have programs for that sort of info.

Re: Disk thruput

labadie_1 — Thu, 05 Feb 2004 09:23:56 GMT

I am a bit puzzled: why not a program ?

You have on the freeware various tools

http://h71000.www7.hp.com/freeware/freeware40/disk_balance/

http://h71000.www7.hp.com/freeware/freeware40/disk_monitor/

http://h71000.www7.hp.com/freeware/freeware60/diskblock058/

which should help you.

regards

Gerard

Re: Disk thruput

Wim Van den Wyngaert — Thu, 05 Feb 2004 09:26:47 GMT

Ian : all kind of disks. Directly attached, MSCP, HSG80, ...
Labadie : I don't want to install things. Just use naked VMS and DCL.

Re: Disk thruput

Hein van den Heuvel — Thu, 05 Feb 2004 09:38:02 GMT

You can not get there from here.
VMS does not have this.
The closest you can get is possibly to
just time a COPY from a large file.
Large files can be created by sysgen,
by create/fdl ... allocation xxx, or my favourite $copy nl: /cont/alloc
Unfortunatly VMS does not have 'dd' (actually... looked in the posix area? ) nor does it have a /dev/zero, only /dev/null so for write tests you'll need to create a large empty file first... or just use a pagefile as input.

- Watch out for 'high-water-marking' when testing IO.

Good luck,
Groetjes,
Hein.

Re: Disk thruput

Ian Miller. — Thu, 05 Feb 2004 11:05:06 GMT

have a look at what MONITOR can do - there may be something you can use to calculate but I don't remember anything specific.

Re: Disk thruput

John Eerenberg — Thu, 05 Feb 2004 11:24:02 GMT

There is a way to get the thruput from DCL but you have to know the typical IO size.

I have several disks dedicated to a database. I know the IO size is 8192 bytes.

$ iocnt1=F$GetDvI("$1$dgannn:","opcnt")
$ wait 00:00:10
$ iocnt2=F$GetDvI("$1$dgannn:","opcnt")
$ kbsec=(iocnt2-iocnt1)*8

kbsec holds the number of KB/Sec for the disks I know the typical IO size. This is a rough number, but at least I get an idea of what is going on.

This can be customized for backup as well if you have a handful of large files (i.e., several GB each) a control-T will tell you the input block size. Very rough though, but it gives you an order of magnitude on the thruput.

Finally this will work if you know the average IO size over a period of time for a disk with a not so cut and dried IO size.

Other then that, no way VMS DCL can give you the info you want.

hope it helps.

Re: Disk thruput

labadie_1 — Thu, 05 Feb 2004 11:24:47 GMT

Ian, may be you were thinking about hyperspi++ ?

http://www.pi-net.dyndns.org/hyperspi++

Re: Disk thruput

Ian Miller. — Thu, 05 Feb 2004 11:26:27 GMT

as the great Steve Hoffman often says 'what problem are you trying to solve?'
Why did you whant disk thoughput figures - do you think you have a problem or are you doing a capacity planning excersise?

Re: Disk thruput

John Eerenberg — Thu, 05 Feb 2004 11:27:07 GMT

Oops...
make that Bytes/Second instead of kbsec
$ bsec=((iocnt2-iocnt1)*8192)/10

Re: Disk thruput

Ian Miller. — Thu, 05 Feb 2004 11:32:48 GMT

information on I/O sizes can be obtained from XFC - see SHOW MEMORY/CACHE/FULL

Re: Disk thruput

Antoniov. — Thu, 05 Feb 2004 12:16:13 GMT

Hello,
there isn't any in DCL that I know; the near program is monitor
MONIT>MONIT DISK
this command show you the I/O operation per disk in system but this can't means nothing; if you use exclusively tha machine, you can make some copy and monit the system, then multiply I/O operation by buffer size (as posted previous) but I think it's not very accuractly.

Bye
Antoniov

Re: Disk thruput

Antoniov. — Thu, 05 Feb 2004 12:21:17 GMT

Oops,
monit disk show operation rate not # of I/O operation.
Antoniov