WHITE PAPER Windows File Sharing (CIFS) Optimization

Transcription

1 Replify Reptor Accelerator Suite Windows File Sharing (CIFS) Optimization REP-WP-CIFS January 2009

2 Contents Windows File Sharing... 3 The Problem with WAN based Windows File Serving... 4 High Latency CIFS File Transfer without Optimization... 5 The Reptor... 6 Reptor Accelerator Optimized CIFS Transfer Results... 7 Reptor & XDR Coherency... 8 Conclusion... 9 References... 9 Reptor s Cross Protocol Data Reduction Technology XDR... 9 About Replify

3 Windows File Sharing The Common Internet File System (CIFS) is the underlying protocol used most commonly when accessing a shared network drive on a Windows based corporate network. It usually comes as part of Windows client and server operating systems and is also available on Linux based systems in another form known as Samba. For example, CIFS is used when dragging and dropping files or directories to or from a shared directory, or editing files across the network in place when performing a network open or executing command line copies across the corporate network. The Reptor Accelerator s CIFS optimization technology described below vastly enhances end user experience for globally accessible network drives, improving key knowledge worker s morale and freeing bandwidth on corporate WAN links. 3

4 The Problem with WAN based Windows File Serving Sharing files and directories between computers on a network using the CIFS protocol first came into general use in 1980s when it was designed to be used on a LAN. Used in this manner it has proven to be an extremely effective and robust protocol, enabling the sharing of Windows directories (and also Samba for UNIX) throughout the corporate LAN. However, with the advent of global corporate networks in recent years and the inherent increase in latency as well as the reduction in available bandwidth between these geographically dispersed offices, the shortcomings of CIFS were quickly exposed. The CIFS protocol is sensitive to high latency networks when used to access files, transfer files and print files over WANs. While objects are usually retrieved over FTP and HTTP with a single request for the full file, CIFS makes several protocol based enquiries about the state of the file before retrieving the file in chunks which range between 4K and 60K. 4

5 High Latency CIFS File Transfer without Optimization When a file of 10MB is being transferred between a client in New York and server in London with a 200ms Return Trip Time (RTT) this can result in many hundreds of round trips to retrieve the file in fragments, each ranging in size between 4K and 60K with only one or two segments being requested at any given time. Replify simulated the transfer of an 11.68MB Word 2003 document, Shakespeare.doc, (sourced from being transferred between New York and London. With an RTT of 200ms and 2Mb bandwidth, the file was dragged and dropped from the server to the local client desktop. Without the Reptor Accelerator, the following results were achieved: Network Roundtrips Time LAN 234 ~1 second WAN 234 1min 2 secs 5

6 The Reptor The Reptor Client and branch office Virtual Appliance intelligently detect when a CIFS file transfer occurs. It will then send a message to the Virtual Appliance in the data center beside the CIFS server which immediately starts to pre-fetch the subsequent parts of the file without waiting for the requests to come across the WAN. This results in much larger chunks of the file being preemptively pushed back to the client, thus availing of the previously wasted available bandwidth. The subsequent request from the CIFS application is parked and then served by the Reptor Client which knows that the payload to fulfill the response is en route from the Reptor Virtual Appliance (assuming that it is not already there). This process will continue until the file has been completely read. The Reptor does not interfere with the CIFS file locking mechanisms and is able to ensure complete file/lock integrity whatever network or application issues arise. 6

7 Reptor Accelerator Optimized CIFS Transfer Results The Shakespeare.doc file was copied over a 2Mb network with 200ms RTT with the Reptor Accelerator optimizing the transfer this time. The first transfer was made when the file had not been seen before and therefore had not yet been propagated to Reptor s XDR memory. Network CIFS Roundtrips Time LAN 234 ~1 second WAN 234 1min 2 secs WAN - Reptor cold XDR 3 15 secs WAN - Reptor hot XDR 3 5 secs 7

8 Reptor & XDR Coherency The Reptor Accelerator s Windows File Sharing optimization was designed to work in perfect harmony with the Reptor Accelerator's network de-duplication technology, XDR (See Reference 1). When coupled with the Reptor's CIFS prefetching technology a bandwidth connection of 2MB which was previously restricted to 60K (by CIFS) can push through many MB per second with an already primed cache. CIFS protocol wrappers are stripped from the data, facilitating cross protocol coherency ensuring that the most efficient use of the XDR memory. Identical payloads for different protocols will match exactly without wastage associated with protocol wrappers around the content. Extending the results table above one can see that the amount of WAN offload for a file of the size 11.6MB can be exceptional. Transfer Time Network Data Network Offload LAN ~1 second bytes x1.0 WAN No Reptor 1min 2 secs bytes x1.0 WAN - Reptor cold XDR 15 secs bytes x4.67 WAN - Reptor hot XDR 5 secs bytes x52.43 XDR coherency and WAN data offloads of many multiples (up to 100 times for frequently accessed larger files) can also alleviate the monthly recurring revenue of the increasing number of mobile sales and support engineers who are accessing their internal network drives using a 3G access card. This can result in a saving of several thousand dollars per gigabyte from monthly corporate bills when a sales team or support workers are in the field and switching between network operators domestically or roaming internationally to foreign networks. 8

9 Conclusion Windows File Sharing continues to be a powerful and cost effective way of enabling the key knowledge workers in a global enterprise to effectively collaborate on business critical documents such as Microsoft PowerPoint presentations, Excel spreadsheets and Word documents. The Replify Reptor Accelerator s CIFS optimization technology has the intelligence to pre-fetch large chunks of the files with each network request, as well as applying compression and data de-duplication with its XDR technology. This effectively removes the pain introduced by high latency and low bandwidth connections and provides a user experience approaching that of the LAN. The Reptor Accelerator makes this optimization mobile when the Reptor Client is installed on the workers lap top which means that the acceleration is always enabled when it is needed most e.g. when connecting from home, a small branch office, customer site or on the road with 3G or even satellite connectivity. Finally, XDR coherency and the massive WAN offload which it offers can result in massively cutting costs for those metered connections such as 3G (or even satellite) workers who pay a premium for the bandwidth being used above a certain level while roaming either internationally or between networks. References Reptor s Cross Protocol Data Reduction Technology XDR 9

10 About Replify Replify is a software vendor dedicated completely to application acceleration. Replify virtualized products accelerate applications over wide area and mobile connections... without the need for costly hardware. Employees will be spared the pain of useless, slow applications when they are remote from the office. Branch offices will be empowered with massively improved application performance, and bandwidth will be spared from unnecessary traffic, resulting in rippling-fast downloads via your wireless data card, lightning fast VPN connections and applications that just run the way they do when you re at the office. In the past, WAN optimization involved investing in expensive new hardware and all the associated costs like energy, rack space, shipping, installation and maintenance. Moreover, application acceleration could be offered just to a select few because of the inherent costs. We also license based on concurrent numbers of users rather than total number. Replify Ltd. Headquarters 4th Floor, Howard House, 1-3 Brunswick Street, Belfast, Northern Ireland, United Kingdom BT2 7GE Tel: +44 (0) Fax : +44 (0) Replify Ltd. EMEA Jonkerbosplein 52, NL-6534 AB Nijmegen, The Netherlands Tel: +31 (0) Fax: +31 (0) info@replify.com The Reptor Accelerator Suite is a software-only solution that gets around these inherent disadvantages of competitive offerings and works with all of the most popular hypervisors including Microsoft s Hyper-V, XenServer, Virtual Iron and VMware. From data center, to branch office to mobile worker all users immediately see the benefit of faster and more responsive applications and data downloads with easy, risk-free installation and a simple, affordable pricing plan. REP-WP-CIFS 01/ Replify Ltd. All rights reserved. This document is for general information purposes only and is subject to change without notice. It may not be accurate, complete or applicable to the circumstances of any particular case. All warranties or representations, expressed or implied are excluded to the fullest extent lawfully permissible. Replify, the Replify device, Replify product names and XDR are trademarks or registered trademarks of Replify Ltd. All other brands, products or service names are, or may be, trademarks or registered trademarks of their respective owners. 10