topic Re: Replace external tape drive. in Operating System - HP-UX

Replace external tape drive.

Abdul Nazar — Thu, 31 Mar 2011 01:08:23 GMT

Hi,

We need to Replace external tape drive HP DAT 72 on rx2600 server. it is a cluster node.Can be replace the tape drive online without shuting down the server? Is there a chance to hang the server when we replace online?

Re: Replace external tape drive.

Steven Schweda — Thu, 31 Mar 2011 02:33:59 GMT

> [...] external tape drive [...]

Not a very detailed description of where it's
connected. Or what else is connected where.

What else is on the same SCSI bus?

On my rx2600, I believe that the built-in
external SCSI port shares a bus with the "2"
disk in the front. So, if that disk is busy,
then you may not want to play with that bus.

If the tape drive is connected to some add-in
PCI SCSI card, and it's the only device on
that bus, then can probably do what you want.

Re: Replace external tape drive.

Abdul Nazar — Thu, 31 Mar 2011 04:18:01 GMT

tape is connected on below given path

ext_bus 3 0/1/1/1 mpt CLAIMED INTERFACE SCSI Ultra320
/dev/mpt3
target 10 0/1/1/1.3 tgt CLAIMED DEVICE
tape 0 0/1/1/1.3.0 stape CLAIMED DEVICE HP C7438A
/dev/rmt/0m /dev/rmt/c3t3d0BESTb /dev/rmt/c3t3d0BESTnb /dev/rmt/c3t3d0DDSb /dev/rmt/c3t3d0DDSnb
/dev/rmt/c3t3d0BEST /dev/rmt/c3t3d0BESTn /dev/rmt/c3t3d0DDS /dev/rmt/c3t3d0DDSn
target 17 0/1/1/1.7 tgt CLAIMED DEVICE
ctl 4 0/1/1/1.7.0 sctl CLAIMED DEVICE Initiator
/dev/rscsi/c3t7d0

No other disks are connected on this path

below given is the path for other internel disks.

target 3 0/1/1/0.0 tgt CLAIMED DEVICE
disk 1 0/1/1/0.0.0 sdisk CLAIMED DEVICE HP 36.4GMAU3036NC
/dev/dsk/c2t0d0 /dev/dsk/c2t0d0s2 /dev/rdsk/c2t0d0 /dev/rdsk/c2t0d0s2
/dev/dsk/c2t0d0s1 /dev/dsk/c2t0d0s3 /dev/rdsk/c2t0d0s1 /dev/rdsk/c2t0d0s3
target 4 0/1/1/0.1 tgt CLAIMED DEVICE
disk 2 0/1/1/0.1.0 sdisk CLAIMED DEVICE HP 36.4GMAU3036NC
/dev/dsk/c2t1d0 /dev/dsk/c2t1d0s2 /dev/rdsk/c2t1d0 /dev/rdsk/c2t1d0s2
/dev/dsk/c2t1d0s1 /dev/dsk/c2t1d0s3 /dev/rdsk/c2t1d0s1 /dev/rdsk/c2t1d0s3
target 9 0/1/1/0.7 tgt CLAIMED DEVICE
ctl 2 0/1/1/0.7.0 sctl CLAIMED DEVICE Initiator

I am attaching the ioscan -fn output.
Please advise whether i can replace tape drive online.

Re: Replace external tape drive.

Torsten. — Thu, 31 Mar 2011 04:19:56 GMT

The official procedure is to power off the bus (the system) before open the bus.

Everything else you do on your own risk.

Re: Replace external tape drive.

Johnson Punniyalingam — Thu, 31 Mar 2011 04:41:07 GMT

Hi,

if the said server rx2600 cluster node is running on cluster pkg.

1.cmhaltpkg -v -n
2.cmhaltcl
3. shutdown -h -> shutdown server.

Than proceed with replacement of external tape drive

else if its passive & no pkg running.

1.cmhaltnode
2.shutdown -h shutdown server

Than proceed with replace of external

Re: Replace external tape drive.

Abid Iqbal — Thu, 31 Mar 2011 06:17:40 GMT

Hi,
Is this tape drive installed in server or tape array?

Re: Replace external tape drive.

Abdul Nazar — Thu, 31 Mar 2011 06:27:23 GMT

It is a single tape drive whcih is attached externally. model C7438A DAT72

Re: Replace external tape drive.

Abid Iqbal — Thu, 31 Mar 2011 06:39:14 GMT

If it is standalone (external) and connected to one of the node via scsi cable, then just
power off the tape, remove the power cable, remove the scsi cable and install new drive and connect scsi cable, power cable and power on the tape drive.
Do ioscan -fnC tape

Re: Replace external tape drive.

Abdul Nazar — Thu, 31 Mar 2011 08:25:29 GMT

Is it officially recommended? Can we try that in a production setup?

Re: Replace external tape drive.

Abid Iqbal — Thu, 31 Mar 2011 08:31:37 GMT

Assuming that this tape drive is not mounted in server body. It is external to server.
Only link is via external scsi cable.
You can perform as described.

Re: Replace external tape drive.

Torsten. — Thu, 31 Mar 2011 08:37:56 GMT

If the device is not hot-plug, then you need to open the bus, may produce a glitch and destroy the device or HBA or more...that's why the recommendation is to power off the whole server.

Re: Replace external tape drive.

Steven Schweda — Thu, 31 Mar 2011 13:28:37 GMT

> [...] may produce a glitch and destroy the
> device or HBA or more... [...]

Lightning may strike you, too.

> Is it officially recommended?

Of course it's not officially recommended.

> Can we try that in a production setup?

How important is it to you not to power down
the system?

> It is a single tape drive whcih is attached
> externally.

With my weak psychic powers, that _still_
doesn't tell me _where_ this drive is
connected to the system.

> tape 0 0/1/1/1.3.0 stape [...]

That looks to me like the built-in external
SCSI port, and I don't see anything else on
that bus (disk bay "2" is empty?), so, if I'm
not missing anything important, then it looks
pretty safe to me.

Around here, I have a disk in bay "2", and my
tape drive has SCSI ID 4, so I see:
[...]
disk 3 0/1/1/1.2.0 sdisk [...]
[...]
tape 0 0/1/1/1.4.0 stape [...]
[...]

If I'm reading your report correctly, then
your tape drive looks like the only "0/1/1/1"
device, so I would not expect any real
trouble if you were to replace that device
(in a static/ESD-safe way) while the system
stays up. I just disconnected and
reconnected my tape drive, and nothing bad
happened. (My disk "2" has Debian GNU/Linux
on it, so HP-UX isn't using it, so everything
on that SCSI bus here was idle when I did that.)

Of course, I won't lose my job if you wreck
something.

Re: Replace external tape drive.

Lashin — Mon, 04 Apr 2011 03:31:31 GMT

external tape drive is attached to controller at "0/1/1/1" and is on the LBA "0/1".there is no other devices on the same cntroller. but there is one more controller"0/1/1/0" attached to same LBA and there are disks connected in this controller. Will it be wise to replace the tape drive online when there are disks connected on same LBA on different controller? Is it officially recommented? the machine is rx2600 and OS is 11.23..We heared that there were cases of server hung when we do it online. Can anybody provide a valid proof/document to present the customer that it is recommended/not recommended?

Re: Replace external tape drive.

Steven Schweda — Mon, 04 Apr 2011 04:03:43 GMT

> [...] Will it be wise to replace the tape
> drive online when there are disks connected
> on same LBA on different controller?

Wise? It depends.

> How important is it to you not to power down
> the system?

Are you reading this stuff? Do you ever
answer questions, or do you only ask the same
questions again (and again)?

> Is it officially recommented?

Did you find an official recommendation?
I doubt that you will find one.

> [...] We heared that there were cases of
> server hung when we do it online.

Heard where? When who did what, exactly?
And is that exactly what you wish to do?

> Can anybody provide a valid proof/document
> to present the customer that it is
> recommended/not recommended?

Are you reading this stuff?

> [...] I just disconnected and
> reconnected my tape drive, and nothing bad
> happened. [...]

If you want complete safety, then shutdown
the OS, and power off everything.

If you want an official statement from HP,
then ask HP customer support. This forum is
not HP customer support.