topic Re: ioscan in SAM takes 10 minutes in Operating System - HP-UX

ioscan in SAM takes 10 minutes

Rommel T. Misa_2 — Mon, 15 Sep 2008 04:57:19 GMT

Hi All,

When I issue ioscan -funC disk at the command line, the output normally takes about only 10 seconds to complete. However, when I do a SAM > Disks and Filesystems > Volume Groups and the system starts to scan I/O channels for the disks, it takes about 10 minutes just to have an output. Has anyone experienced this? What's the fix to this problem (if indeed it is)?

Please help.

ROMMEL

Re: ioscan in SAM takes 10 minutes

Duncan Edmonstone — Mon, 15 Sep 2008 05:26:29 GMT

Rommel,

The disks and filesystems section in SAM has *always* been painfully slow (it does more than just an ioscan), but lets be sure that you don't have an ioscan problem anyway.

How long does:

ioscan -f

and ioscan -fn

take? If they only take about 10 seconds then it's just slow old SAM. If it takes longer you may have some bad devices attached somewhere (quite often its down to bad zoning on fibre channel switches)

HTH

Duncan

Re: ioscan in SAM takes 10 minutes

SKR_1 — Mon, 15 Sep 2008 06:28:42 GMT

>> (it does more than just an ioscan),

Hi Duncan

Can you please explain it in detail. What is the main difference b/w ioscan on command line and ioscan from SAM.

Thanks

SKR

Re: ioscan in SAM takes 10 minutes

Rommel T. Misa_2 — Mon, 15 Sep 2008 06:47:23 GMT

ioscan -fn and ioscan -fnC disk takes as long as in SAM (10 mins). :(

Re: ioscan in SAM takes 10 minutes

Duncan Edmonstone — Mon, 15 Sep 2008 06:56:49 GMT

Too much to list here, but you can see for yourself by doing the following:

1) Start SAM
2) Select Disks and Filesystems
3) From another window go to the sam log directory:

cd /var/sam/log

4) Copy out the sam log and zero the file. Then tail the file so you can watch progress

cp samlog samlog.bak
>samlog
tail -f samlog

5) Back in your SAM session select Disk Devices and immmediately switch back to your other window - you'll now be able to watch the progress of the SAM scanning progress and watch all the other things it does....

6) When done just use CTRL-C to exit the tail -f

HTH

Duncan

Re: ioscan in SAM takes 10 minutes

Duncan Edmonstone — Mon, 15 Sep 2008 07:01:31 GMT

If those ioscans tale a long time too then some device somewhere may be misconfigured. The usual culprit is something on a SAN (is this system running on a SAN?) So the next step is to narrow down the problem by looking at the FC cards in turn.

Identify the path to the FC cards using:

ioscan -funC fc

Then just run the scans on the hardware paths of the FC cards and below with:

ioscan -fnH

e.g.

ioscan -fnH 0/4/2/0

Do those take about 10 minutes or only one of them?

HTH

Duncan

Re: ioscan in SAM takes 10 minutes

SKR_1 — Mon, 15 Sep 2008 07:08:22 GMT

Thanks Duncan

SKR

Re: ioscan in SAM takes 10 minutes

Steven E. Protter — Mon, 15 Sep 2008 07:55:57 GMT

Shalom,

Usually this is a sign of termination problems in the scsi chain or missing disks that were presented and now not present on storage.

It can also be caused by a failed disk.

Check all these issues and proceed to solution.

I have experienced this more times than I can count.

SEP

Re: ioscan in SAM takes 10 minutes

Bill Hassell — Mon, 15 Sep 2008 10:08:05 GMT

> ioscan takes a long time...

That's why I never use ioscan without the -k except when adding/deleting devices with power on. Even then, I limit the scope of ioscan to just a hardware path or category:

ioscan -knfC disk

ioscan -knfH 1/0/12/1/1

The -k guarentees instant output and reflects what the kernel knows about the devices. There is no reason to hard-scan all the devices unless you are rezoning a SAN switch or adding a hotswap disk.

SAM's volume group section is indeed very slow on large systems as it not only runs a full ioscan but also checks *every* physical disk and volume group. If you have several hundred disks, it will indeed be very slow. I would recommend SAM to manage volume groups and disks on large systems. The command line is much faster.

Re: ioscan in SAM takes 10 minutes

Torsten. — Mon, 15 Sep 2008 10:55:29 GMT

A very common problem is, if the server is connected to a SAN but there are no devices visible. The system searches, searches ...

Can you post the output of

# ioscan -fnk

Re: ioscan in SAM takes 10 minutes

PCIS — Mon, 15 Sep 2008 15:17:18 GMT

Hello
I'have already this kind of issue.

You need to publish on your san a host lun begining by zero.

cyt0d0, if you don't have this lun, you server will make a full scan to discover your SAN.

So you can try to verify, if your lun aren't protected or invalidate.

Regards

Nicolas

Re: ioscan in SAM takes 10 minutes

Rommel T. Misa_2 — Wed, 17 Sep 2008 01:08:28 GMT

Hello all,

I did what Duncan suggested, that is, to monitor the samlog as I am issuing SAM>Disks and File Systems. Attached is the samlog. I think it's in ioscan where it takes too long. If you have time, you might want to take a look at the attachment.

Thanks,
ROMMEL

Re: ioscan in SAM takes 10 minutes

Rommel T. Misa_2 — Wed, 17 Sep 2008 01:15:28 GMT

To Nicolas,

Do you mean that I have to have this LUN configured first? And yes, my system is connected to an SAN.

ROMMEL

Re: ioscan in SAM takes 10 minutes

Rommel T. Misa_2 — Wed, 17 Sep 2008 04:48:35 GMT

I have attached the output of ioscan -fnk here. When I issued the command

# ioscan -fnH 0/0/14/1/0

the output of this command takes about 7 mins.

ROMMEL

Re: ioscan in SAM takes 10 minutes

Torsten. — Wed, 17 Sep 2008 04:56:47 GMT

Well, looks like a large SAN.

Did you separate disks and tapes by zoning?

Re: ioscan in SAM takes 10 minutes

PCIS — Wed, 17 Sep 2008 07:18:45 GMT

Yes Romel, you need to have this lun.

On hitachi 9500 series and tagmastore, you need to have an hosted lun than begin by 0.

ldev 3 > hosted 0
ldev 24 > hosted 1
ldev 35 > hosted 2

etc.

If you don't have this hosted lun, the system scan the full range possible hosted device 1 to 255.

Becareful if you are on a wide san, check all you storage device, maybe you'are in this case too.

Regards
Nicolas

Re: ioscan in SAM takes 10 minutes

PCIS — Wed, 17 Sep 2008 07:26:02 GMT

I saw,

you have /dev/dsk/c20t0d0./dev/dsk/c18t0d0

You are not in the same case than me.

You can try to remove path by path and see if something change.

Nicolas