Original Message:
Sent: Fri March 31, 2023 07:34 AM
From: Satid Singkorapoom
Subject: Virtual I/O Server - Best Practices
Dear Tom
>>>> VIOS does not participate in LPM, so having VIOS boot from SAN or internal didn't aid nor hinder your migration. <<<<
I forgot to mention that the reason for a decision for VIOS boot from SAN in the case I mentioned was that it used not much of disk space from SAN. The BP said it would not need to adjust the proposed config of Storwize because of this fact. The customer saw no need to buy additional internal disk just for this reason and therefore they saw they saved their investment. So, the reason was not technical but a financial one.
As for the reason of reliability or availability, my experience taught me that we need to look at this as part of a WHOLISTIC picture of the matter so that its value is justified. A colleague of mine used to share with me a case when VIOS booted from internal disk but client LPARs used NPIV to connect to SAN. But then one day, someone messed up with the SAN somewhere and caused the LPARs to stop working. To the customer's perspective, the fact that additional investment for VIOS's boot from internal disk for an independent reliability or availability did not provide value in this particularly unfortunate case. When the customer regards availability, they care more about availability of their business workload LPAR rather than VIOS.
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Education is not the learning of facts but the training of the mind to think. -- Albert Einstein.
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Satid S.
Original Message:
Sent: Fri March 31, 2023 07:02 AM
From: Tom McGivern
Subject: Virtual I/O Server - Best Practices
Satid, VIOS does not participate in LPM, so having VIOS boot from SAN or internal didn't aid nor hinder your migration.
Nigel, I agree with you except his question was specific to booting the VIOS. KISS in that case points to internal (explained below)
Suleman,
In my experience, self contained VIOS (boot internal), avoids any issues with missing/aged device drivers. Depending on the storage manufacturer, you may need ODM tweaks, and new device drivers. We used Hitachi, they needed these things. You can't install directly to something you need third-party stuff to support.
while you may be ok today, what about after their next SAN refresh when they change vendors?
if the VIO boots from internal disk, then you have the hardware up and running, and you can at least always log into an OS to diagnose / support the system.
Yes, it's more expensive, but they're paying for the Reliability, Availability, Serviceability of IBM/power for a reason! Don't jeopardize all that to save a few bucks.
Tom
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Tom McGivern
Original Message:
Sent: Fri March 31, 2023 03:45 AM
From: Satid Singkorapoom
Subject: Virtual I/O Server - Best Practices
Dear Suleman
There is a redbook for this: IBM PowerVM Best Practices at https://redbooks.ibm.com/abstracts/sg248062.html. But its chapter 5 on Storage topic does not cover the aspect you asked about.
To answer your question and to know if what you said is "expensive" would be the case or not, we need to know more about the HW and logical environment and expectation you are dealing with. What more can you tell us on this?
I would say the answer to your question lies in practical aspect of the matter. For example, I used to provide support to a customer who wanted to migrate 60 small IBM i and AIX LPARs (serving many branches across the globe) with dual VIOS from two POWER7 servers to two POWER9 servers as well as to migrate from DS8K SAN disk to Storwize and they wanted minimum downtime for the entire migration. We saw that using offline partition mobility (as opposed to backup and restore approach) is a solution to match the customer's requirement and this clearly needed SAN. Internal disk was out of the question. So, we also decided VIOS would boot from SAN.
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Education is not the learning of facts but the training of the mind to think. -- Albert Einstein.
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Satid S.
Original Message:
Sent: Thu March 30, 2023 10:59 PM
From: Suleman Malik
Subject: Virtual I/O Server - Best Practices
Hi Team,
I am looking for best-practices document for deploying a Virtual I/O server for my business partner. Their question
"I need to decide where to boot the VIOS from – internal storage or SAN storage" - The Power10 systems sacrifice PCIe slot(s) for the NVMe breakout to use the front panel storage slots. This makes internal storage 'expensive', as you lose the opportunity to use those PCIe slots.
Just want to know if there is a best practice that everyone else is using.
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Suleman Malik
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