Scott Hanselman

The real and complete story - Does Windows defragment your SSD?

December 3, '14 Comments [56] Posted in Win7 | Win8
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There has been a LOT of confusion around Windows, SSDs (hard drives), and whether or not they are getting automatically defragmented by automatic maintenance tasks in Windows.

There's a general rule of thumb or statement that "defragging an SSD is always a bad idea." I think we can agree we've all heard this before. We've all been told that SSDs don't last forever and when they die, they just poof and die. SSDs can only handle a finite number of writes before things start going bad. This is of course true of regular spinning rust hard drives, but the conventional wisdom around SSDs is to avoid writes that are perceived as unnecessary.

Does Windows really defrag your SSD?

I've seen statements around the web like this:

I just noticed that the defragsvc is hammering the internal disk on my machine.  To my understanding defrag provides no value add on an SSD and so is disabled by default when the installer determines the disk is SSD.  I was thinking it could be TRIM working, but I thought that was internal to the SSD and so the OS wouldn’t even see the IO.

One of the most popular blog posts on the topic of defrag and SSDs under Windows is by Vadim Sterkin. Vadim's analysis has a lot going on. He can see that defrag is doing something, but it's not clear why, how, or for how long. What's the real story? Something is clearly running, but what is it doing and why?

I made some inquiries internally, got what I thought was a definitive answer and waded in with a comment. However, my comment, while declarative, was wrong.

Windows doesn’t defrag SSDs. Full stop. If it reports as an SSD it doesn’t get defraged, no matter what. This is just a no-op message. There’s no bug here, sorry. - Me in the Past

I dug deeper and talked to developers on the Windows storage team and this post is written in conjunction with them to answer the question, once and for all

"What's the deal with SSDs, Windows and Defrag, and more importantly, is Windows doing the RIGHT THING?"

It turns out that the answer is more nuanced than just yes or no, as is common with technical questions.

The short answer is, yes, Windows does sometimes defragment SSDs, yes, it's important to intelligently and appropriately defrag SSDs, and yes, Windows is smart about how it treats your SSD.

The long answer is this.

Actually Scott and Vadim are both wrong. Storage Optimizer will defrag an SSD once a month if volume snapshots are enabled. This is by design and necessary due to slow volsnap copy on write performance on fragmented SSD volumes. It’s also somewhat of a misconception that fragmentation is not a problem on SSDs. If an SSD gets too fragmented you can hit maximum file fragmentation (when the metadata can’t represent any more file fragments) which will result in errors when you try to write/extend a file. Furthermore, more file fragments means more metadata to process while reading/writing a file, which can lead to slower performance.

As far as Retrim is concerned, this command should run on the schedule specified in the dfrgui UI. Retrim is necessary because of the way TRIM is processed in the file systems. Due to the varying performance of hardware responding to TRIM, TRIM is processed asynchronously by the file system. When a file is deleted or space is otherwise freed, the file system queues the trim request to be processed. To limit the peek resource usage this queue may only grow to a maximum number of trim requests. If the queue is of max size, incoming TRIM requests may be dropped. This is okay because we will periodically come through and do a Retrim with Storage Optimizer. The Retrim is done at a granularity that should avoid hitting the maximum TRIM request queue size where TRIMs are dropped.

Wow, that's awesome and dense. Let's tease it apart a little.

When he says volume snapshots or "volsnap" he means the Volume Shadow Copy system in Windows. This is used and enabled by Windows System Restore when it takes a snapshot of your system and saves it so you can rollback to a previous system state. I used this just yesterday when I install a bad driver. A bit of advanced info here - Defrag will only run on your SSD if volsnap is turned on, and volsnap is turned on by System Restore as one needs the other. You could turn off System Restore if you want, but that turns off a pretty important safety net for Windows.

One developer added this comment, which I think is right on.

I think the major misconception is that most people have a very outdated model of disk\file layout, and how SSDs work.

First, yes, your SSD will get intelligently defragmented once a month. Fragmentation, while less of a performance problem on SSDs vs traditional hard drives is still a problem. SSDS *do* get fragmented.

It's also worth pointing out that what we (old-timers) think about as "defrag.exe" as a UI is really "optimize your storage" now. It was defrag in the past and now it's a larger disk health automated system.

Used under CC. Photo by Simon WüllhorstAdditionally, there is a maximum level of fragmentation that the file system can handle. Fragmentation has long been considered as primarily a performance issue with traditional hard drives. When a disk gets fragmented, a singular file can exist in pieces in different locations on a physical drive. That physical drive then needs to seek around collecting pieces of the file and that takes extra time.

This kind of fragmentation still happens on SSDs, even though their performance characteristics are very different. The file systems metadata keeps track of fragments and can only keep track of so many. Defragmentation in cases like this is not only useful, but absolutely needed.

SSDs also have the concept of TRIM. While TRIM (retrim) is a separate concept from fragmentation, it is still handled by the Windows Storage Optimizer subsystem and the schedule is managed by the same UI from the User's perspective. TRIM is a way for SSDs to mark data blocks as being not in use. Writing to empty blocks on an SSD is faster that writing to blocks in use as those need to be erased before writing to them again. SSDs internally work very differently from traditional hard drives and don't usually know what sectors are in use and what is free space. Deleting something means marking it as not in use. TRIM lets the operating system notify the SSD that a page is no longer in use and this hint gives the SSD more information which results in fewer writes, and theoretically longer operating life. 

In the old days, you would sometimes be told by power users to run this at the command line to see if TRIM was enabled for your SSD. A zero result indicates it is.

fsutil behavior query DisableDeleteNotify

However, this stuff is handled by Windows today in 2014, and you can trust that it's "doing the right thing." Windows 7, along with 8 and 8.1 come with appropriate and intelligent defaults and you don't need to change them for optimal disk performance. This is also true with Server SKUs like Windows Server 2008R2 and later.

Conclusion

No, Windows is not foolishly or blindly running a defrag on your SSD every night, and no, Windows defrag isn't shortening the life of your SSD unnecessarily. Modern SSDs don't work the same way that we are used to with traditional hard drives.

Yes, your SSD's file system sometimes needs a kind of defragmentation and that's handled by Windows, monthly by default, when appropriate. The intent is to maximize performance and a long life. If you disable defragmentation completely, you are taking a risk that your filesystem metadata could reach maximum fragmentation and get you potentially in trouble.

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* photo by Simon Wüllhorst, used under CC BY 2.0.

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Getting ready for the future with the Microsoft .NET Portability Analyzer

December 3, '14 Comments [11] Posted in Learning .NET
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.NET has been getting more and more portable. Not only is .NET Open Source going forward (read Announcing .NET 2015 - .NET as Open Source, .NET on Mac and Linux, and Visual Studio Community) but you of course know about Xamarin tools, as well as, I hope, the .NET Microframework, and much more.

You can run your .NET code all over, and there's a tool to make this even easier. While you'll rarely get 100% portable code with any platform, you can get into the magic 90-95% with smart refactoring, then keep the platform-specific shims pluggable.

The .NET Portability Analyzer is a free Visual Studio Add-in (or console app) that will give you a detailed report on how portable your code is. Then you can get a real sense of how far you can take your code, as well as how prepared you'll be for the Core CLR and alternate platforms.

.NET Portability

Take a look at this report on AutoFac, for example. You can see that the main assembly is in fantastic shape across most platforms. Understandably the more platform-specific Configuration assembly fares worse, but still there's a complete list of what methods are available on what platforms, and a clear way forward.

.NET Portability Report

You'll get suggestions with a direction to head when you bump up against a missing or not-recommended API.

img2

You can analyze specific assemblies, or an entire project. Once installed, you'll find the commands under the Analyze menu, and you can change options in the .NET Portability Analyzer options in the Tools | Options menu.

Even better, you can use this with the FREE Visual Studio Community that you can download at http://www.visualstudio.com/free.

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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OmniSharp - Making cross-platform .NET a reality, and a pleasure

November 27, '14 Comments [53] Posted in ASP.NET | Open Source
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In case you missed it, make sure to read Announcing .NET 2015 - .NET as Open Source, .NET on Mac and Linux, and Visual Studio Community because there's been some big stuff going on.

Here's the summary of the .NET 2015 Wave of awesomeness.

The other thing I wanted to talk about is a newly organized group of technologies called OmniSharp. Just to be sure there's no confusion, OmniSharp isn't a Microsoft project. While there are two Microsoft folks on the team of 8 or so, we are working on it as community members, not in an official capacity.

I "launched" this project in my talk at the Connect() mini-conference in New York a few weeks back. You can watch that video here on Channel 9 now if you like. However, the technologies around and under OmniSharp have been around for years...like over a decade!

As a team and a community we pulled together a bunch of projects and plugins, got organized, and created https://github.com/omnisharp and http://www.omnisharp.net. Jonathan Channon has a great overview blog post you should check out that talks about how Jason Imison created OmniSharpServer which is an...

HTTP wrapper around NRefactory allowing C# editor plugins to be written in any language. NRefactory is the C# analysis library used in the SharpDevelop and MonoDevelop IDEs. It allows applications to easily analyze both syntax and semantics of C# programs. It is quite similar to Microsoft's Roslyn project; except that it is not a full compiler – NRefactory only analyzes C# code, it does not generate IL code.

OmniSharp runs as its own process and runs a local Nancy-based web api that your editor of choice talks to. If you have an editor that you like to use, why not get involved and make a plugin? Perhaps for Eclipse?

We now have plugins for these editors:

  • Sublime
  • Brackets from Adobe
  • Atom from GitHub
  • Emacs
  • Vim

And these work on (so far) all platforms! It's about choice. We wanted to bring more than autocomplete (which is basically "I think you typed that before") to your editor, instead we want actual type-smart intellisense, as well as more sophisticated features like refactoring, format document, and lots of other stuff you'd expect only to see in Visual Studio.

We also brought in the Sublime Kulture package which gives Sublime users support for ASP.NET 5 (formerly ASP.NET vNext), so they can launch Kestrel (our libuv based local webserver), run Entity Framework migrations, and other arbitrary commands from within Sublime.

.NET in Sublime, in Vim, in Brackets, in Atom, and everywhere else, cross-platform

Here's OmniSharp running in emacs on my Windows machine. The emacs setup (here is an example) is a little more complex than the others, but it also gives emacs folks an extreme level of control. Note that I had to launch the OmniSharp server manually for emacs, while it launches automatically for the other editors.

image

Here is an ASP.NET MVC app running in Sublime. The Sublime OmniSharp package output can be seen in the debug console there (Ctrl+~ to see it).

image

OmniSharp is in very active development. We are looking at bringing in Roslyn, using the new ASP.NET Design Time Host, and improving robustness. It's not perfect, but it's pretty darn cool. There's lots of details in Jonathan's writeup with great animated gifs showing features. Also note that we have a Yeoman generator for ASP.NET that can get you started when creating ASP.NET 5 apps on Mac or Linux. The yeoman generator can create Console apps, MVC apps, and NancyFx apps.

You can get started at http://omnisharp.net.  See you there!

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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ASP.NET 5 (vNext) Work in Progress - Exploring TagHelpers

November 20, '14 Comments [138] Posted in ASP.NET | ASP.NET MVC
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TagHelpers are a new feature of ASP.NET 5 (formerly and colloquially ASP.NET vNext) but it's taken me (and others) some time to fully digest them and what they mean.

Note that this, and all of ASP.NET 5 is a work in progress. TagHelpers can and will change. There is NO tooling support in Visual Studio for them, as they are changing day to day, so just be aware. That's why this post (and series is called Work in Progress.)

Historically we've used HtmlHelpers within a Razor View, so when you wanted a Label or a TextBox you'd do this. This is from the ASP.NET 5 Starter Web example.

<li>@Html.ActionLink("Home", "Index", "Home")</li>

There you have some HTML, then we start some C# with @ and then switch out. It's inline C#, calling a function that will return HTML.

Here's the same thing, using a TagHelper.

<li><a controller="Home" action="Index">Home</a></li>

The source for TagHelpers is (as with all ASP.NET source) up on GitHub, here. This is an anchor, A, so it'll be in AnchorTagHelper. The code is very simple, in fact, gets a collection of attributes and decides which to act upon.

In this case, "controller" and "action" are not HTML5 attributes, but rather ones that ASP.NET is looking for.

Question for You - Would you rather have these attributes and ones like them (including your own) be prefixed? Perhaps asp:controller or asp-controller? That's an open issue you can comment on! You could do [HtmlAttributeName("asp:whatever")] on a property or [TagName("foo")] for a tag if you liked.

How do these attributes get mapped to a TagHelper? Well, an attribute name is mapped directly to a C# property and automatically injected. See how AnchorTagHelper has public properties Action and Controller?

It's important to note that this isn't the second coming of WebForms controls, while the possible asp:foo syntax may look familiar (even though a prefix is optional.) This is more like syntactic sugar that gives you a compact way to express your intent. It doesn't give you any "control lifecycle" or anything like that.

Personally, I'd love to see them look different in the editor. For example, rather than

Tag Helpers

I'd like to see italics, or maybe a desaturation to show what's server-side and what's not, which will be super important if I'm NOT using a prefix to distinguish my attributes.

Tag Helpers, desaturated

The code below in this Before and After results in the same HTML and the same behavior. A nice aspect of TagHelpers it that you avoid the context switch from markup to C#.

Here is another example, a login partial form, before...

@using System.Security.Principal

@if (User.Identity.IsAuthenticated)
{
using (Html.BeginForm("LogOff", "Account", FormMethod.Post, new { id = "logoutForm", @class = "navbar-right" }))
{
@Html.AntiForgeryToken()
<ul class="nav navbar-nav navbar-right">
<li>
@Html.ActionLink("Hello " + User.Identity.GetUserName() + "!", "Manage", "Account", routeValues: null, htmlAttributes: new { title = "Manage" })
</li>
<li><a href="javascript:document.getElementById('logoutForm').submit()">Log off</a></li>
</ul>
}
}
else
{
<ul class="nav navbar-nav navbar-right">
<li>@Html.ActionLink("Register", "Register", "Account", routeValues: null, htmlAttributes: new { id = "registerLink" })</li>
<li>@Html.ActionLink("Log in", "Login", "Account", routeValues: null, htmlAttributes: new { id = "loginLink" })</li>
</ul>
}

and after...with the Microsoft.AspNet.Mvc.TagHelpers package added in project.json and then @addtaghelper "MyAssemblyName" in either your ViewStart.cshtml to get this in all views, or separately within a single view page.

@using System.Security.Principal

@if (User.Identity.IsAuthenticated)
{
<form method="post" controller="Account" action="LogOff" id="logoutForm" class="navbar-right">
<ul class="nav navbar-nav navbar-right">
<li>
<a controller="Account" action="Manage" title="Manage">Hello @User.Identity.GetUserName()!</a>
</li>
<li><a href="javascript:document.getElementById('logoutForm').submit()">Log off</a></li>
</ul>
</form>
}
else
{
<ul class="nav navbar-nav navbar-right">
<li><a id="registerLink" controller="Account" action="Register">Register</a></li>
<li><a id="loginLink" controller="Account" action="Login">Log in</a></li>
</ul>
}

This makes for much cleaner markup-focused Views. Note that this Sample is a spike that Damian Edwards has on his GitHub, but you have TagHelpers in the Beta 1 build included with Visual Studio 2015 preview or OmniSharp. Get involved!

Remember also to check out http://www.asp.net/vnext and subscribe to my YouTube Channel and this playlist of the ASP.NET Weekly Community Standup. In this episode we talked about TagHelpers in depth!

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Announcing .NET 2015 - .NET as Open Source, .NET on Mac and Linux, and Visual Studio Community

November 12, '14 Comments [193] Posted in ASP.NET | ASP.NET MVC | Open Source | VS2015
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It's happening. It's the reason that a lot of us came to work for Microsoft, and I think it's both the end of an era but also the beginning of amazing things to come.

The .NET 2015 wave of releases is upon us. Here's what's happening and we announced it today in New York. There's a lot here, so drink it all in slowly.

Be sure to check out all the blog posts I'm linking to at the end, but here's my personal rollup and take on the situation.

  • We are serious about open source and cross platform.
    • .NET Core 5 is the modern, componentized framework that ships via NuGet. That means you can ship a private version of the .NET Core Framework with your app. Other apps' versions can't change your app's behavior.
    • We are building a .NET Core CLR for Windows, Mac and Linux and it will be both open source and it will be supported by Microsoft. It'll all happen at https://github.com/dotnet.
    • We are open sourcing the RyuJit and the .NET GC and making them both cross-platform.
  • ASP.NET 5 will work everywhere.
    • ASP.NET 5 will be available for Windows, Mac, and Linux. Mac and Linux support will come soon and it's all going to happen in the open on GitHub at https://github.com/aspnet.
    • ASP.NET 5 will include a web server for Mac and Linux called kestrel built on libuv. It's similar to the one that comes with node, and you could front it with Nginx for production, for example.
  • Developers should have a great experience.
    • There is a new FREE SKU for Visual Studio for open source developers and students called Visual Studio Community. It supports extensions and lots more all in one download. This is not Express. This is basically Pro.
    • Visual Studio 2015 and ASP.NET 5 will support gulp, grunt, bower and npm for front end developers.
    • A community team (including myself and Sayed from the ASP.NET and web tools team) have created the OmniSharp organization along with the Kulture build system as a way to bring real Intellisense to Sublime, Atom, Brackets, Vim, and Emacs on Windows, Linux, and Mac. Check out http://www.omnisharp.net as well as blog posts by team members Jonathan Channon
  • Even more open source.
    • Much of the .NET Core Framework 4.6 and its Reference Source source is going on GitHub. It's being relicensed under the MIT license, so Mono (and you!) can use that source code in their .NET implementations.
    • There's a new hub for Microsoft open source that is hosted GitHub at http://microsoft.github.io.

Open sourcing .NET makes good sense. It makes good business sense, good community sense, and today everyone at Microsoft see this like we do.

Open .NET

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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.