Ahsay Offsite Backup Manager Evaluation

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<P class="vtitle"><IMG src="http://wiki.r1soft.com/download/attachments/4227111/pdf_icon.gif" style="margin: 0pt 10px 0pt 0pt; float: left;"></IMG> <A href="http://wiki.r1soft.com/pages/doexportpage.action?pageId=5439736&type=TYPE_PDF">Ahsay Offsite Backup Manager Evaluation</A> </P></DIV>{html}
\\ {excerpt}How Does Ahsay Online / Remote / Offsite Backup Manager Compare to R1Soft CDP {excerpt}
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Ahsay Systems Corporation&nbsp; is a Hong Kong based software developer that makes Ahsay Backup Software originally called Leb Shama Company Ltd.&nbsp; [Ahsay was first developed in September of 2000|http://www.ahsay.com/en/general/ahsay_general_corporate_profile.html].&nbsp; Ahsay is designed around {color:black}efficient{color} backups of small offices over slow wide area network links like DSL lines.&nbsp;
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To Achieve this Ahsay uses a check sum method to compute deltas and&nbsp;do incremental file based backups.&nbsp;The goal of Ahsay's software is to make it possible to backup very large files on a daily basis as described in Ahsay's Ahsay Online Backup Whitepaper - In-File Delta&nbsp;available at [http://www.ahsay.com/download/customer/document/whitepaper_obm_infile-delta.pdf].&nbsp;&nbsp;&nbsp;

Ahsay's software is file based&nbsp;meaning it must examine and index every file on the disk during a backup operation.&nbsp; The biggest challenge for Ahsay is that every file must be read from disk to compute deltas no matter how little or how much data has actually changed.&nbsp; This process can easily take hours just to compute the deltas on a typical file server.&nbsp;&nbsp;Ahsay described two modes of backups it's software can perform.&nbsp;
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* Ahsay Differential Delta Mode
* Ahsay Incremental Delta Mode
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*Ahsay Differential Delta Mode* \- works by creating an initial backup of all files.&nbsp; Then for every incremental it computes deltas representing the differences between the original first full backup and the current file set.&nbsp; There are several major draw backs to this approach.&nbsp; Another challenge with the differential delta mode in particular is that each incremental backup consumes more and more disk space and network bandwidth.&nbsp; As time passes there are more and more differences between the current files and the original first full backup.&nbsp; Furthermore changes in one backup set are copies again and again to the next incremental duplicating data.

The advantage of Ahsay's Differential Delta Mode is that restore is faster as restore requires that the original full backup file is combined with the latest set of deltas.

This is very similar to the basic behavior of {color:black}differential{color} tape backup.&nbsp;

To read more about Differential Backups visit: [Backup Method - Differential|TP:Backup Method - Differential]

*Ahsay Incremental Delta Mode -* works by comparing the latest version of a file to the last incremental backup.&nbsp; The advantage is that backups take up less space as deltas are not duplicated like they are in Ahsay's differential delta mode.&nbsp; The disadvantage is that in addition o the first full backup all previous backups are required to return a file to a particular point in time.&nbsp;

This is very similar to the attributes of a basic incremental tape backup.&nbsp;

To read more about Incremental Backups visit: [Backup Method - Incremental Backup|TP:Backup Method - Incremental Backup]&nbsp;

*Computing Deltas&nbsp;with Ahsay*

Ahsay uses a fixed block size based on initial file size when computing deltas.&nbsp; A major improvement over Ahsay is the rsync protocol which uses variable length blocks and check sums to increase delta matches and reduce delta computation times.
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h2. Technology Comparison

|| || Ahsay Offsite Backup Manager \\ || R1Soft Continuous Data Protection \\ ||
| Backup Software Technology Category \\ | [Legacy|TP:Categories of MySQL Backup Software] | [Continuous Data Protection|TP:Categories of Backup Software] \\ |
| Backup Method Used \\ | [Incremental|TP:Backup Method - Incremental Backup]& [Differential|TP:Backup Method - Differential]\\ | [Virtual Full|TP:Backup Method - Virtual Full Backup]\\ |
| Data Lost In Disaster \\ | Days \\
_(improved on Windows Desktops_ \\
_with Ahsay 5.5 and CDP for files)_ \\ | Minutes \\ |
| File or Block Level \\ | [File Level|TP:File Based Backup Technology]\\ | [Block Level|TP:Block Based Backup Technology] \\ |
| Method for Computing Deltas \\ | [Check Sums|TP:Computing Deltas - Check Sums]\\ | [CDP|TP:Computing Deltas - near-Continuous (CDP)]&nbsp; \\ |
| Backup Window Length \\ | {color:#000000}Hours or Days{color}&nbsp; \\ | {color:#000000}Minutes when CDP is in Sync{color}&nbsp; \\ |
| Online Backup (Snapshots)&nbsp; \\ | {color:#000000}Windows Only{color} | {color:#000000}Yes Integral Part of the Product{color}&nbsp; \\ |
| Bare-Metal Restore \\ | No \\ | Yes \\ |
| Backup Window Critical Path \\ | {color:#000000}= Time to Read All Data from Disks{color} \\
&nbsp; (needed to compute checksums) &nbsp; | {color:#000000}= Only Time to Read Deltas{color}&nbsp; \\ |
| Core Technological Concept \\ | Remote Branch Office Backup \\
Windows Desktop Backup \\
Backup over DSL and Cable Modem \\
Small Office Backups \\
MS Outlook&nbsp;/ Outlook Express \\
Reselling Branch Office Backups \\ | Minimal Backup Window \\
Little or No Load on Production Server \\
Virtual Full Backups \\
Continuous Data Protection \\
Proprietary Device Drivers \\
Web Interface \\
Easy of Deployment \\
Manageability \\
Data Centers \\
Multi-User&nbsp; \\ |
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h2. Ahsay Continuous Data Protection for Files Feature (Windows only)

Ahsay has added a method of detecting changes to files they call "Continuous Data Protection".&nbsp; Ahsay's continuous data protection works by having a daemon run on Windows servers that monitors when files are saved.&nbsp; When files are saved and detected the daemon schedules a backup of the file.&nbsp; This triggers delta computation on the full file.&nbsp; The changed files contents are read from disk to compute deltas and the deltas are sent to the Ahsay backup server creating another backup point-in-time for that file.

*Advantages*
* Saved files are instantly backed up.&nbsp;
* There is no waiting for a scheduled backup operation or even a scheduled CDP synchronization like R1Soft CDP performs.&nbsp;
* Designed for Desktops

*Disadvantages*
* Ahsay CDP for Files is Only Available on Windows.&nbsp; There is No Linux support for this feature.&nbsp;
* A resource intensive program must run constantly tracking changes to the file system to detect the saved file.&nbsp; The program consumes both memory and CPU resources and Ahsay warns it can potentially slow down a computer considerably.&nbsp; It is not recommended for servers.&nbsp; See page 30 section 5.4 (Continuous Data Protection) of the AhsayOBS v5.5 User's Guide: [http://pedia.ahsay.com/display/2n/kb/article.aspx?aid=1752&n=6&s=1]
* Ahsay must read the changed files full contents from disk to compute deltas.&nbsp; This is very resource intensive.
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h2. Linux Server Data Protection

|| || Ahsay Offsite Backup Manager&nbsp; || R1Soft Continuous Data Protection ||
| Easy To Use Web Interface \\ | No&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \\ | Yes |
| Point-in-Time Snapshots \\ | No | Yes \\ |
| Bare-Metal Restore \\ | No \\ | Yes \\ |
| Real-Time Backup (backup without interrupting your work) \\ | No | Yes \\ |
| Hourly or Minutely Backups \\ | No \\ | Yes \\ |
| Backup Archiving \\ | Yes \\ | Yes \\ |
| Virtual Full Backups \\ | No \\ | Yes \\ |
| Significantly Reduce Disk I/O Load with Linux Kernel Level CDP \\ | No \\ | Yes \\ |

h2. Windows Server Data Protection

|| || Ahsay Offsite Backup Manager || R1Soft Continuous Data Protection ||
| Easy To Use Web Interface \\ | No&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \\ | Yes |
| Point-in-Time Snapshots \\ | Yes \\ | Yes \\ |
| Bare-Metal Restore \\ | No | Yes \\ |
| Real-Time Backup (backup without interrupting your work)&nbsp; \\ | No \\ | Yes \\ |
| Hourly or Minutely Backups \\ | No \\ | Yes \\ |
| Backup Archiving \\ | Yes \\ | Yes \\ |
| Virtual Full Backups \\ | No \\ | Yes \\ |
| Significantly Reduce Disk I/O Load with R1Soft Windows CDP Volume Filter Driver \\ | No \\ | Yes \\ |
| Windows Volume Shadow Copy Service Integration \\ | Yes \\ | Yes \\ |
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h2. Special Features for Hosting Service Providers and Resellers

|| || Acronis True Image Enterprise Server || R1Soft Continuous Data Protection \\ ||
| Easy To Use Web Interface \\ | No &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; \\ | Yes&nbsp;&nbsp; \\ |
| Multi-User System for Backup and Restore with Granular Permissions \\ | Yes | Yes \\ |
| Customer self-managed backup and restore \\ | Yes \\ | Yes \\ |
| Quotas for Backup Storage \\ | Yes&nbsp; \\ | Yes \\ |