Monthly Archives: July 2011

OnTAP version issues

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Last week (on the 24th) I performed a routine OnTAP upgrade across 5 of my 3170 filers; I upgraded from 7.3.5 to 7.3.5.1P5. This upgrade was performed to help prevent a system panic from happening, which had happened twice before on our stand alone 3170 snapvault target system, under Bug 446493. Here is the Bug description:

Much disk and shelf hardware can be managed by an ANSI-standard technology called SCSI Enclosure Services (SES).  To support SES-related processing, the SES subsystem of Data ONTAP schedules various periodic actions, using an internal timeout mechanism.

Due to a software defect, under certain conditions, the SES subsystem may set an excessive number of timers, with new timers being set before old ones expire.  If this continues, an internal callout table will fill up, triggering an interruption of processing.

One condition in which the problem can occur is during initial setup and configuration of the storage system:  when the “cluster-setup wizard” is run, it asks the administrator for configuration input as follows:

Do you want to create a new cluster or join an existing cluster? {create, join}: (Login timeout will occur in 60 seconds)

When installing releases in which the defect is present, if this prompt is allowed to time out, an interruption may occur at some later time.

However, the callout table can also fill up during routine production, if storage events occur in rapid succession, such that SES scans are rapidly invoked.  Such events may include:

  •  a continuing series of disk errors
  •  breakages in disk-communication links
  • adding new shelves
  • power-cycling shelves
  • removing a power supply
  • shelf firmware updates
  • shelf faults
  • takeover/giveback

We were hitting this bung under the “continuing series of disk errors” event, which caused the SES scans to fill the timer-callout table. When this happened the system would panic and reboot. After the upgrade I performed all standard checkouts and everything appeared to be functioning normally and within standards, so I closed the upgrade processes and marked it as successful.

Then on the 26th we attempted to perform an allocation using the NMC. While going through all the steps everything appeared as though it was going well, all of the checks passed and we hit commit, only to have the process came back with an error message indicating that the process had failed. After opening a support call with NetApp and providing both screen captures of the error received and steps to reproduce, it was determined that we had run it to another bug. This time we hit Bug 474612. Here is the bug description:

system-cli API returns cli-result-value with an invalid return status. This invalid return status may break OnCommand and other third party applications utilizing NMSDK.

Basically what is happening is the NMC is executing the requested commands, but the filer cli is returning a response code that the NMC is not expecting and in fact does not recognize. When this happens the NMC does not know how to proceed and the command fails without performing the provisioning. Apparently this issue was introduced in OnTAP 7.3.5.1P4 and still exists in 1P5, so the solution is to downgrade OnTAP to 7.3.5.1P3. In this version of OnTAP bug 446493 is resolved and bug 474612 has not yet been introduced (as of this writing, bug 474612 is NOT resolved in any version of OnTAP).

After performing the downgrade tonight to OnTAP 7.3.5.1P3 I performed all normal checkouts and additionally performed the pending allocation via the NMC to verify the functionality and non-existence of bug 474612 in this version of OnTAP. Happily the allocation went through without issue, and from what we can tell all aspects of the filers are functioning normally. Our next OnTAP upgrade will have to be to 7.3.6.

Xbox down…again

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Well isn’t that just my luck, and the reason I prepare for such! The new replacement Xbox decided to stop reading disks yesterday, and today is exactly 30 days since I got it. I took the unit back to GameStop and they replaced it under the original 30 day warranty on the unit. They also gave me a new 30 day warranty on this unit, cancelled the one year warranty I purchased on the now dead unit, and reapplied it to this new unit so that I will have a a full year warranty on this unit. I hope this one will work better, and longer.

Thoughts of my Father

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In five years I do not think a day has gone by that I have not thought about my Father. I see him every time I look in the mirror, and hear his voice when I need advice. He is with me everyday, in my memories and in the love I share with my daughter. I learned how to be a man by watching him. I’m not going to say he was perfect, because he wasn’t, but he did try. I learned a lot from him, both things I wanted to emulate and things I learned that I did not. He taught me many things, both tangible things like shaving and non-tangible things like integrity. There were things, too, that I could not learn from him because by the time I was old enough to learn he was to sick to be able to teach me, like hunting. But we still spoke about those things, sometimes for hours on end, and threw those conversations he was still able to pass on his knowledge to me. My father never graduated high school, and yet he was one of the smartest people I’ll ever know. I remember seeing him read a lot, and watching a lot of TV shows that, at the time, I may have thought were boring, but now realize they were very educational. Then I realize that this is probably why I also enjoy watching, for instance, the History Channel so much. I’m not sure what has made me have this reminiscence today, but I feel close to him today and I am happy. I miss you Dad, and I love you.

Peregrine Falcon Rescue

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Today Kylie, Melissa and I had a very strange, and probably rare, experience. We got to help rescue an injured Peregrine Falcon. We were on our way to Target to get Kylie anew bathing suit, and as we passed the car wash next to Meijer Daddy saw the Falcon standing under a tree. After turning around and going back we were realized that the Falcon was injured. There was another lady there who said she had already called the humane society and was waiting for their emergency animal pick up, so we went on to Target. While we were there Daddy made a few phone calls to track down other possible places for the falcon to go, but none were available. When we left to back home the falcon was still there and other people had gathered as well. This time when we pulled in we found out that the emergency pick-up personnel from the humane society was not going to be able to come for the falcon as they were dealing with another issue elsewhere. They suggested that if someone could get a blanket over the falcon and gently wrap it, that we could then put the raptor in a box and bring it to the humane society. Other people were currently trying to get the falcon, but all they had was a T-shirt, and that’s when Daddy remembered that we have a blanket in the truck. After getting the blanket, and working in coordination with the two other people who were trying to get the falcon, Daddy was able to get behind the falcon and drape the blanket over it and then gentle hold and wrap it, pick it up and place it in a box. We then followed some other helpers to the humane society. When we got there we gave the falcon to their emergency unit, but they came back out a few minutes later and told us they were not going to be able to save the falcon; it’s wing was badly broken and it’s one claw was badly mangled, unfortunately that had to euthanize the falcon. Even though there was a sad ending for the falcon, we all felt really good that we at least tried to help the bird. We were able to take a few pictures of the injured falcon, also a video of us catching the falcon.

The problems with combining FC and SATA drives on the same NetApp

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The idea of tiered storage is something many business are seriously exploring now a days, and combining and leveraging it with and for “cloud” operations is a major focus. The idea behind tiered storage is that you have different levels of disk that have different performance characteristics, with the main focuses being speed and performance. We recently looked in to the possibility of adding some tiering to one of the NetApp environment’s I manage. The idea was to use 300GB FC (Fibre Channel) as our Tier 1 NAS disk and some 1TB SATA as our Tier2. On the surface of things this seems like a good idea for a couple of reasons:

  1. The Tier 1 disk is sufficient enough to run Oracle databases over NFS if those databases are configured properly.
  2. The Tier 2 disk is much cheaper and would be perfect for housing non-critical non-performance intense shares, such as home directories, at a fraction of the cost
  3. The mix of available disk would allow us to tailor the allocations to the actual needs of the project based on their performance requirements.

So as I began to look in to this course of action I discovered a few things that completely negates this idea, at least for having it housed in one filer (or a clustered pair even):

  • When using FC connectivity to disk shelves, FC drive and SATA drives must go on different loops.  This means that if you add a shelf of SATA to an open FC port on a filer, you will not be able to add any FC drives to that loop.
  • All write operations are committed to disk as a group, regardless of what the destination aggregate is for those writes.  So, on a system with SATA and FC disk, write operations destined for FC drives may be slowed down by the writes going to the SATA drives, if the SATA drives are busy.

The first point, the dedicated loops, isn’t such a big deal if you are planning on adding a full loop worth of SATA shelves (6 shelves per loop) and you have an open FC port with nothing else attached (or can move other shelves to fill in open spots on other loops to free up an FC port). So while the dedicated loop can be resolved and may or may not be an issue depending on your set up, it’s the second point that poses the most trouble in our environment (and I would assume most others as well).

Running the risk of impacting performance to your Tier 1 disk is not acceptable. The applications running on that tier are there for a reason, they need the performance of those faster disks. But how do you know if you will hit that impact, maybe it won’t apply? Good question. Perhaps this won’t be an issue for your environment. So ask your self this: Do you know the exact details of your workloads? No of course you don’t. You may know that there are databases on some of the exports, or that certain exports are used for regular CIFS or NFS shares for home directories, but you most likely do not know all the intimate details of each given applications work load. Without that precise knowledge it is nearly impossible to quantify the potential impact ahead of time, and thus this possible latency becomes a real concern.

Because of these factors we choose (and I recommend) not mixing FC and SATA shelves on a single (or clustered) system. If you need to have multiple Tiers you still have options:

  • Implement SAN as your Tier 1 storage and utilize NAS as Tier 2
  • Implement a Tier 1 NAS environment and a Tier 2 Nas environment on separate hardware (read: separate physical systems, either single headed or clustered)
  • Look into an appliance that can handle different types of disk in the same housing without impact and configure tiering therein.

Tiering your storage is great idea and allows for many flexibilities and possible cost savings for the customer in terms of charge backs for disk utilization. Even so, you still need keep performance in mind, and for me, the possible performance impact is not worth the risk for mixing these shelf types on a single head.

Hopefully Just a Summer Break?

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After a little over a year of playing, today Kylie has informed me that she no longer wants to play violin. She called me this morning while she was on the way to Aunt Melissa’s for the day and she said she doesn’t want to play anymore and asked if that was ok. Even though it makes me very sad as I thought she was doing very well and I personally love the sound of violin and fiddle music, I have no desire to force her to do something she is not interested in, so today will be her last day. She will go tonight and talk with Aerial, her instructor, and say good bye. Mommy and I think that this may just be a set back caused by the unstructured nature of summer break and are hoping that she might pick it back up once school starts up again in the fall. We think this because it seems since school let out Kylie has been getting a little more unfocused on the violin and we think it is due to the lack of structure during the rest of her day on Monday and in the other days of the week. I guess we will just have to wait and see what happens come fall, personally I hope she picks it back up.