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Book Review: Citrix XenApp Performance Essentials

samzenpus posted about a year ago | from the read-all-about-it dept.

Books 24

First time accepted submitter gbrambilla writes "A problem every system administrator has to face sooner or later is to improve the performance of the infrastructure that he administers. This is especially true if the infrastructure is a Citrix XenApp farm that publishes applications to the users, that starts complaining as soon as those applications become slow. A couple of weeks ago I was asked to publish a new ERP application and suddenly all the hosted applications started to suffer performance problems... after some basic tests I looked on Amazon for an help and found the book I'm reviewing: Citrix XenApp Performance Essentials, by Luca Dentella, is a practical guide that helps system administrators to identify bottlenecks, solve performance problems and optimize XenApp farms thanks to best-practices and real-world examples." Read below for the rest of gbrambilla's review.A well-designed infrastructure may help to solve a lot of headaches when the infrastructure is in production... in chapter 1 the book explains the most important elements of a XenApp infrastructure (session-host servers, datastore servers, web interface servers...), their role, how they work together and how to correctly size them based on the number of users and applications that will be served. This chapter includes not only best practices from Citrix, but also precious suggestions that come from author's experience with real Citrix farms.

When a farm is in production and users start to connect and work with published applications, it's very important to monitor its performance: in chapter 2 Luca explains how to monitor it, from the basic Windows Performance counters to the use of advanced Citrix tools. XenApp offers several advanced settings (CPU Utilization Management, Memory Optimization, Load evaluators ...) to improve the performance: all these features are covered in the second half of this chapter, including the new ones of version 6.5.

A typical complaint about applications published by XenApp is that they start slowly... this is usually caused by slow session start-up. Chapter 3 teaches the most frequent causes of slowness and how to reduce the start-up time, including the use of the new features of XenApp 6.5 (Session Sharing and Lingering).

Multimedia applications are becoming more and more frequently published by XenApp farms, that's why Luca wrote a chapter, the fourth, to explain the technologies Citrix offers under the "HDX" brand and how you can take advantage of them for publishing video/audio/VoIP applications.

The last chapter is about remote users, i.e. users that connect to the farm using WAN (wide-area networks) connections. Citrix offers different optimizations and Citrix administrators can work together with network admins to improve the user-experience with the use of QoS, priorities... It's usually hard to understand how published applications work with slow, laggy links; Luca found an opensource tool, named WanEM, that can simulate every kind of links; in chapter 5 you'll also learn how to use it.

This book is not for people looking for a for dummies manual about Citrix XenApp: it won't teach you what is XenApp, how to install your first XenApp server or how to publish your first application. It's intended for intermediate-expert Citrix administrators that need a pratical, quick guide about an important task of their job: make sure the farms they administer work well. The first chapter is also a must read for all those IT Architects that are designing or planning a new installation: I've seen several projects fail or miss their business goals because of bad-designed architectures (presence of single point of failure, undersized servers...).

This book is also an interesting read for administrators courious about the new features of Citrix XenApp 6.5: some of them (for example session pre-launch) can be a significative improvement in your existing farm.

As the title suggest, this is not a huge book (about 130 pages), this means that not all the topics are deeply explained... sometimes you'll probably need the help of Google to find Citrix how-tos or docs to implement what is suggested: do not expect a step-by-step guide but a book that introduces many advanced features you can implement possibly with the help of Citrix manuals.

A special mention for chapter 5, maybe a good read with the help of a network colleague: it explains what Citrix can do to help the network guys to optimize the connection (Quality of Service, WAN scalers...) for remote users.

I was satisfied about this book and I think it's worth buying: I consider myself an "expert" system administrator but I must admit I didn't know some of the features explained in this book and I realized that I didn't fully understood others: for example Luca gives an excellent explanation about what is DLL collision, a problem that on Windows OSes can cause waste of RAM memory.

You can purchase Citrix XenApp Performance Essentials from amazon.com. Slashdot welcomes readers' book reviews (sci-fi included) -- to see your own review here, read the book review guidelines, then visit the submission page.

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Seems a bit out of date (1, Troll)

h4rr4r (612664) | about a year ago | (#44926817)

XenApp is basically dead, XenDesktop 7 does everything it did and what Xendesktop always did. So maybe this book is a little behind the times.

Re:Seems a bit out of date (1)

afidel (530433) | about a year ago | (#44927031)

LOL, until MS licensing changes XenDesktop won't be a replacement for existing XenApp farms, plus XenApp is significantly more memory efficient than loading up an entire OS image for each user.

Re:Seems a bit out of date (1)

h4rr4r (612664) | about a year ago | (#44927135)

Shared hosted is available with XenDesktop 7. It literally is exactly what XenApp used to do.

Re:Seems a bit out of date (1)

jon3k (691256) | about a year ago | (#44928143)

The problem for us was the licensing requirements [techtarget.com] . It was FAR cheaper to just deploy published desktops on Windows Server than it was to use XenDesktop. I'm not familiar with XenDesktop 7, so I'm not sure if it functions the same, in that regard, to XenApp 6.5.

Re:Seems a bit out of date (0)

Anonymous Coward | about a year ago | (#44927077)

XenApp is certainly NOT dead. Some companies only want to support delivering applications without desktops. If you've already invested in a XenApp infrastructure, converting your licenses to XenDesktop doesn't make sense if you don't need or WANT those features as you'll lose a quantity of licenses for those extra features. Just my 2 cents...

Re:Seems a bit out of date (1)

h4rr4r (612664) | about a year ago | (#44927151)

XenDesktop 7 does that too. XenDesktop 7 does everything XenApp ever did.
Your new licenses will at some point be XenDesktop only.

Re:Seems a bit out of date (0)

Anonymous Coward | about a year ago | (#44927347)

As a former Citrix employee I can verify that XenApp is not dead. It is bundled with XenDesktop, but you still need to install a XenApp Server to use the Shared Hosted Desktop/App features in XenDesktop. Think of XenDesktop as Microsoft Office and XenApp as just one of the components (Outlook for example).

Re:Seems a bit out of date (1)

h4rr4r (612664) | about a year ago | (#44927715)

Not as of XenDesktop 7. You setup your storefront and mangement servers, you install the xendesktop agent on the Windows RDS server and away you go.

Re:Seems a bit out of date (1)

Ben4jammin (1233084) | about a year ago | (#44927831)

Not only that, but I would venture that the install base for 6.5 is large enough and will be around long enough that this is still relevant. I just migrated a 4.0 farm to 6.5, and year before last in training for 6.0 there were several participants still on older farms. Once working (and my experience is that 4.0 and 6.5 work well) these things tend to "linger" for a while.

I'll probably pick this book up because I doubt I have seen my last 6.5 farm

Re:Seems a bit out of date (1)

gbrambilla (3045373) | about a year ago | (#44932883)

Hi I think the following blog post explains the "vision" behind XenDesktop 7: http://blogs.gartner.com/gunnar-berger/xendesktop-7-is-xenapp-7-the-missing-ingredient-at-citrix-synergy/ [gartner.com] anyway it's a complete revolution for a XenApp infrastructure: I think the transition will be very slow for existing farms!

Citrix?!? (0)

Anonymous Coward | about a year ago | (#44927035)


A seriously false way towards a cheaper, easier to maintain desktop. My advice is to go work someplace else.

Re:Citrix?!? (1)

drainbramage (588291) | about a year ago | (#44927119)

Looks like he can 'go work someplace else' now that he has finished his training on that production system.

To "silo" or not. (2)

khasim (1285) | about a year ago | (#44927185)

The real question is whether you install all the apps on all the servers OR whether you assign specific servers to specific apps.

After that, QoS can help but we're rapidly getting to the point where every app vendor wants their app to have priority. It's fine with VoIP ... and admin utilities ... and video conferencing ... and Citrix ... and ... video apps running over Citrix ...

I'm serious. I've had to support video apps running over Citrix and it completely changes the methodology of what can be cached where to provide decent performance. Is it because people don't understand multicasting?

Re:To "silo" or not. (1)

jon3k (691256) | about a year ago | (#44928167)

Multicast doesn't work in a lot of scenarios. Multicast requires scheduled video delivery, not so much on demand video delivery. I definitely feel your pain, delivering video via Citrix royally fucks up QoS policies. And Citrix had an opportunity to help out if they would have delivered HDX over a separate set of ports, but nope, regular ol 1494 ICA. So now from a network perspective I can't prioritize video inside a Citrix session on the WAN.

Re:To "silo" or not. (0)

Anonymous Coward | about a year ago | (#44929823)

Look into their WAN optimization product, cloud branch bridge, or something like that.

Re:To "silo" or not. (0)

Anonymous Coward | about a year ago | (#44932173)


Re:To "silo" or not. (0)

Anonymous Coward | about a year ago | (#44928173)

Well, I'd say you should assign specific servers to specific apps. You can have a baseline, which all servers can run, like Outlook and SAP. Then come the specific apps for this and that part of your organisation, quite often used only in one or two sites, home-brew apps... Then you'll have a bunch of apps requiring IE7. These may not work well with other web-based apps. And so on.

In the end you'll end up with a chart of apps, thick/thin client, local/remote database, IE version, Java version, this and that version requirements... and you'll start creating silos according to which app can live next to another. You may also like to take into consideration the two users on app A (used once every quarter, but pushed by management) opposed to 100 users of app B (which people really need every day).

And then: every app has different patch release cycle, when you need to reboot a whole bunch of servers in the middle of the day. Your company works 24/7, so you can't avoid middle of the day, it will always be a bad time somewhere in the world.

I don't think the question is silo or not silo. The question is how much, because you need to keep order, otherwise it will become very ugly mess. Keep it clean. Daily operation will give you answers.

Re:To "silo" or not. (1)

afidel (530433) | about a year ago | (#44928303)

Silo'd is often a requirement because you'll have mutually exclusive dependencies, like we have one app that must have Acrobat in standalone mode because it uses a plugin that breaks in embedded mode and we have another app that embeds pdf's into the page where the workflow doesn't work if it's setup for standalone mode.

Fuck off and die Dice (0)

Anonymous Coward | about a year ago | (#44927241)


Rubbish (0)

Anonymous Coward | about a year ago | (#44927981)

I found the book rubbish - don't buy it.

I have but one piece of useful advice on Xenapp (2)

SuricouRaven (1897204) | about a year ago | (#44929051)

Make sure you know everything there is to know about not just xenapp, but how windows handles profiles too - because they will eventually give you problems, and you'd better be equipped to fix them.

Re:I have but one piece of useful advice on Xenapp (1)

gbrambilla (3045373) | about a year ago | (#44932903)

Hi this is a very good advice: I found that many slowness problems were caused by big roaming profiles... Citrix Profile Manager is a good solution!

Re:I have but one piece of useful advice on Xenapp (1)

pnutjam (523990) | about a year ago | (#44952893)

Too true, and don't forget Group Policies...
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