In Part 2 of this series we made our first API call and received over 200 lines of XML as a result. The reason why we received so much output is because we didn’t remove any
desired-attributes and therefore the call retrieved about 90 pieces of information. When you multiply that by the number of queries we ran (2), you get 180 pieces of information being requested.
This post will discuss why you should limit your queries to only the pieces of information you’re interested in. It will also cover how you can use ZExplore to convert its XML configuration to languages such as Python, Perl and Ruby.
Picking up where I left off in Part 1 of this series, let’s continue our exploration of ZExplore :)
In part 1 I touched on the fact that the API documentation can be a little confusing when it comes to mandatory fields. Unfortunately the same is true for ZExplore. However, NetApp’s documentation explains it well:
Red colored arrows indicate mandatory parameters whereas Blue colored arrows indicate optional parameters.
Note: In some APIs when either one of the two input parameters is required, both these input parameters are marked by “Blue” color arrow and not “Red”.
As I mentioned in my previous post, by doing this NetApp avoids confusing users who might otherwise try to set both parameters if they were both marked as required.
If you’re a regular reader of this blog, you’ll see that I’ve been posting about automation and Python quite a lot recently. The reason being that it’s not only fun, but I feel it’s the way of the future. But I digress…
The reason for this post is to discuss my recent experience with NetApp’s APIs. As I got off to a pretty slow start (which I feel was due to lack of documentation), I’ll also provide setup and usage guidance in the hopes that you can get up and running sooner than I did.
Just under a year ago I wrote a blog series called NetApp From The Ground Up – A Beginner’s Gude. Since the publication of the series I have been getting e-mails, Tweets and LinkedIn messages from people asking for more. So here it is – The NetApp Zero to Hero Guide.
This series of posts is aimed at people who have zero storage knowledge. Each post will build on from the last and together they will assist the reader in becoming a storage hero :)
I thought I’d write up a quick blog post to celebrate the fact that NetApp Insight is around the corner!
If you haven’t seen them already you can find my NetApp posts here. To jump directly to my “NetApp From the Ground Up – A Beginner’s Guide” series of posts click here.
Finally, keep an eye on my Twitter account (@OzNetNerd) and the #NetAppATeam hashtag to see what the other A Team members and I get up to while we’re over there. Oh and of course there’s always the #NetAppInsight hashtag too!
… as you can probably tell, I’m a little excited :)
Snapshot copy reserve sets a specific percent of the disk space for storing Snapshot copies. If the Snapshot copies exceed the reserve space, they spill into the active file system and this process is called snapreserveSnapshot spill.
The Snapshot copy reserve must have sufficient space allocated for the Snapshot copies. If the Snapshot copies exceeds the reserve space, you must delete the existing Snapshot copies from the active file system to recover the space, for the use of the file system. You can also modify the percent of disk space that is allotted to Snapshot copies.
The Snapshot copy reserve sets a specific percent of the disk space for Snapshot copies. For traditional volumes, the default Snapshot copy reserve is set to 20 percent of the disk space. For FlexVol volumes, the default Snapshot copy reserve is set to 5 percent of the disk space.
The active file system cannot consume the Snapshot copy reserve space, but the Snapshot copy reserve, if exhausted, can use space in the active file system.
Volume and Aggregate Reallocation
- Volume Reallocation: Spreads a volume across all disks in an aggregate
- Aggregate Reallocation: Optimises free space in the aggregate by ensuring free space is contiguous.
One of the most misunderstood topics I have seen with NetApp FAS systems is reallocation. There are two types of reallocation that can be run on these systems; one for files and volumes and another for aggregates. The process is run in the background, and although the goal is to optimize placement of data blocks both serve a different purpose. Below is a picture of a 4 disk aggregate with 2 volumes, one orange and one yellow.
If we add a new disk to this aggregate, and we don’t run volume level reallocation all new writes will happen on the area in the aggregate that has the most contiguous free space. As we can see from the picture below this area is the new disk. Since new data is usually the most accessed data you now have this single disk servicing most of your reads and writes. This will create a “hot disk”, and performance issues.
Disk drives from different manufacturers may differ slightly in size even though they belong to the same size category. Right sizing ensures that disks are compatible regardless of manufacturer. Data ONTAP right sizes disks to compensate for different manufacturers producing different raw-sized disks.
Much has been said about usable disk storage capacity and unfortunately, many of us take the marketing capacity number given by the manufacturer in verbatim. For example, 1TB does not really equate to 1TB in usable terms and that is something you engineers out there should be informing to the customers.
NetApp, ever since the beginning, has been subjected to the scrutiny of the customers and competitors alike about their usable capacity and I intend to correct this misconception. And the key of this misconception is to understand what is the capacity before rightsizing (BR) and after rightsizing (AR).
(Note: Rightsizing in the NetApp world is well documented and widely accepted with different views. It is part of how WAFL uses the disks but one has to be aware that not many other storage vendors publish their rightsizing process, if any)
- Reference: NetApp Training – Fast Track 101: NetApp Portfolio
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Multiple Clustered NetApp Systems
- Reference: NetApp Training – Fast Track 101: NetApp Portfolio
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