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Understanding backup |
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Kay Ewbank finds out what's important when you're considering a backup solution, and which are the leading products in the field. |
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A modern IT system is a very reliable beast. Built-in duplication and uninterruptable power supplies mean that your data is in pretty safe hands. Nevertheless, only the foolhardy would do without a backup system, and all but the smallest of organisations would do well to look beyond the basic backup facilities that come built in to the modern operating system. As we shall see, a backup system provides much more than simply duplication of data so that it can be recovered in the event of loss.
Archiving
Just as you might archive old bank statements in case you need to refer to them in the future, so a data archive allows you to keep older data for legal or audit compliance purposes. This is not the same as simple backup, and indeed if you are running a business and need to keep copies of data for a specific length of time, you may need to keep a backup of the archive. There are statutory requirements that require contracts to be kept for 6 years, for example, while financial organisations may have to keep records for 25 years or more.
Ideally, an archive solution should give you the means to prove that the data has not been altered once placed in the archive. Either way, any archive system should be able to give you easy access to the archived data when necessary.
Backup selection
While there are many types of data that are vital to your business, and so vital that you back up, there may also be a lot of data in your system that you don’t need to back up, or that you have no responsibility to back up, such as personal images, audio files or emails that your employees are keeping on your system. All backup solutions allow you to select which drives and which directories to back up, but some allow you to set more sophisticated selection rules that could save you a lot of space.
Disk imaging
Backing up data need not mean taking a copy of your data files. It might be more appropriate to take a disk image. Disk image backup involves making a bit-for-bit copy of a complete data storage device, such as a hard disk or a DVD. The image is stored as a single file, made by copying the individual sectors of the original medium. If you need to restore the drive, you have a perfect copy that can simply be recreated without having to reconstruct the device one data file at a time.
Continuous data protection
If your data changes frequently and you need to be sure that nothing is lost, then a scheduled backup will not provide sufficient protection. Instead you need to have continuous data protection. This monitors the disk continuously, recording every change that is made. Usually, this is carried out at a low level recording changes to individual blocks or sectors, rather than when a complete file is saved.
Data encryption
Data is valuable and people may try to steal it, particularly when it is backed up onto a medium that can easily be taken out of the business premises. Encryption is not without problems, however. Encrypting data takes time and reduces the effectiveness of subsequent data compression utilities as the obvious patterns of normal data are hidden by the encryption. However, if your backup solution requires data to be transferred to an offsite storage location then encrypting it first ensures the data is secure while in transit.
Protection agents
Some of the most valuable data in your organisation can be the most difficult to back up. Databases and email central storage present problems because the data is constantly in use, so every time the backup software attempts to copy the files, the operation is cancelled because the file is open and backing up an open file can result in inconsistencies with partial changes to data.
The traditional solution is to do the backup at times when few or no employees are working – after midnight, for example. However this has its own problems. You only need one late night worker to prevent a daily backup being taken, while a failure late in the afternoon loses an entire day’s work. A better solution is to use a protection agent. This is a piece of software that comes into play while a file is being backed up. If the file is marked open then the protection agent intercepts all the changes that would have been applied. These changes are stored in a buffer and then applied to the file once the backup is completed.
Virtualisation
Virtualisation is a technique which packages an operating system and its applications into a ‘virtual machine’ and then runs a number of such virtualised machines on a single server that is running a host operating system or hypervisor. The problem is that each virtual machine has its own data that needs to be backed up.
One option is to install the backup software on each virtual machine and then to back up the data to a standard backup device such as a tape drive. This can cause problems because backup can be heavy on system resources, so starving the other virtual machines while backing up. It’s also important to stagger backups so that only one virtual machine is backed up at a time.
Virtualisation software providers such as Microsoft and VMware provide tools specifically for backing up virtualised machines which work by taking a snapshot of the entire disk drive. This can then be used to create identical copies of the virtual machines.
Generational backup
The most common problem with recovering data from a backup (apart from discovering there was never anything being recorded onto the tapes) is that the error you’re trying to recover from has been faithfully recorded onto the backup. One method of avoiding this is to use a ‘grandfather-father-son’ backup, otherwise known as generational backup.
The basic idea is that you have three copies of the data at any one time. On the first day you make a backup on Tape One. The next day, you make a backup onto Tape Two, and the third day you make a backup onto Tape Three. You then re-use Tape One on day four. A similar technique can be adopted no matter what backup medium you use, and whatever the frequency of your backups, so that you always have three copies each taken at a different time. If an error occurs and is propagated to one copy then hopefully the earlier copies will be clean, even though more data will have changed in the interim.
Backup solutions
Symantec
Symantec’s backup solutions include Veritas NetBackup, Backup Exec and Backup Exec System Recovery. Veritas NetBackup provides data protection for UNIX, Windows, Linux and NetWare environments. It is designed to protect the entire enterprise, from remote offices to the central data vault, from a single console.
Backup Exec and Backup Exec System Recovery are certified for use on Windows Server 2008 and earlier, and the latest versions are integrated with other Symantec products so that, for example, you can have Backup Exec trigger a backup if the Symantec ThreatCon system shows an increased likelihood of a widespread security attack. Backup Exec provides continuous file and data protection, including Microsoft Exchange, SQL Server databases and Active Directory data. The software makes use of Microsoft Volume Shadow Copy Services (VSS) snapshot integrations to improve performance. If a file is open, it will still be backed up. There is also an agent available for working with Oracle databases. The software includes 256-bit AES encryption and data can be encrypted across the network or to the storage device.
Backup Exec has good management options with support for load-balancing and bandwidth throttling to ensure the network and servers remain usable while backup is in progress. There are good monitoring and reporting features, and you can monitor all your servers across the network and even in remote offices. Backup options include disk-to-disk and disk-to-tape, or disk-to-disk-to-tape where older backups are migrated to slower tape systems. The software is also integrated with Symantec’s Online Storage, so you can store data off-site at Symantec’s storage facilities.
Backup Exec System Recovery is concerned with the system as well as the data, and the backups it creates can be used to recover a server onto similar or different hardware. You can also recover to a virtual server.
Computer Associates
ARCserver Backup from Computer Associates allows you to manage multiple
servers and clients from its main window.Computer Associates ARCserve Backup has versions available for file servers, email servers, database servers and application servers. You can manage multiple servers and clients from its main window, including data replicated from remote offices. ARCserve integrates with CA’s XOsoft replication software to give a simpler way to deal with backing up branch offices. You don’t need to have the hardware or the staff available on site to handle the backups; instead, you just back up on a central backup server.
ARCserve has good support for applications that would normally prove problematic because their nature means they are always in use. To overcome this, ARCserve comes with protection agents for all the big-name SQL databases, SAP, Exchange, Lotus Notes and Novell GroupWise.
The choice of backup device for ARCserve is comprehensive and it’s easy to mix and match. You can back up to tape, disk, or disk to disk to tape. You manage your backup devices from the console where the main backup server controls a hierarchy of other backup servers. You can choose which servers should be used for backing up and restoring, and can manage the local devices for each server. ARCserve supports VTL (virtual tape libraries) and you can also use VSS snapshots. Encryption comes in the form of FIPS certified AES 256 Bit encryption and hardware-based tape drive encryption.
If you’re backing up virtualised servers, ARCserve has an agent for VMWare that supports VMware ESX virtual machines.
The management console in ARCserve has good facilities for ensuring successful backups and for disaster recovery. In normal use you’re shown potential problems with your backup jobs, along with options for correcting the problems. If something goes wrong and you need to recover a particular server, ARCserve allows you to customise the server’s parameters so the recovery has the best possible chance of getting you up and running.
Acronis
Acronis True Image Echo range has products that you can use for backing up systems ranging from workstations to enterprise servers with versions for Windows and Linux, and support for virtual machines. As the name suggests, the True Image range create an image of the hard disk of a machine, including the operating system, applications, user settings and all data. If a problem occurs then the image can be used to restore the entire machine either to the same or a different computer. You don’t have to back up or restore the entire machine either: you can specify individual file types for particular applications, or exclude particular file types to concentrate on business data.
Acronis has a central management console from which you can back up and restore machines across the network, and the software can do more than merely take disk images. You can take 
Acronis True Image Echo creates disk images that can be restored to both
physical and virtual machines.images of dynamic disks and of data that is spread across multiple disk volumes. You can encrypt the images to keep them secure. It’s also possible to change data in existing disk images by loading them for read/write and then applying the necessary changes. The data generated by application servers such as Microsoft Exchange, SQL Server and Oracle can be backed up while running. Another useful option is the ability to run scripts before or after you take a backup to ensure company backup policies are being met.
The software supports VMware Consolidated Backup if you’re using VMware ESX servers to handle virtual machines. One nice touch is the ability to take a standard image file and convert it to a format suitable for use in creating a virtualised machine. You can convert to formats for use in VMware, Microsoft Virtual Server, SWsoft or Parallels.
If problems do occur and you need to restore your machines, you can restore them across the network from the central console, and even boot a system from the image so that essential systems are brought back up as quickly as possible.
Yosemite
Yosemite Backup is available in four versions to suit different environments, starting with the Single Server Edition through to a version designed to protect large numbers of servers. Yosemite Backup will run natively on Windows, Netware or Linux. The software consists of a Master Server that handles local backup and scheduling and gives you a central management console for managing Media Servers and Client Servers. You can run all three on a single system if necessary, or divide the servers across multiple machines.
The management console is designed for ease of use with task Wizards to guide you through the creation and running of backup jobs, adding and managing backup media and devices, and recovering data. This ease of use is also seen in a self-tuning option that analyses the configuration of your data sources and the archiving devices you have installed and automatically selects the most effective drive to device configuration.
Yosemite takes the route of providing the core of the software for the basic licence fee with features such as native support for Exchange and SQL Server as options that can be turned on if required in your organisation.
Yosemite supports both software and hardware data encryption. The software encryption has three levels of security while the hardware encryption supports a range of hardware-based devices including LTO-4. You can optionally add support for storage hardware such as backup to disk, Storage Area Networks (SAN) and iSCSI.
The basic modules provide protection for open files using Microsoft Volume Shadow Copy Service, but if your servers don’t support this you have the option of using St. Bernard Open File Protection. Native protection agents are also available for Microsoft Exchange and Microsoft SQL Server to enable them to be backed up while in use.
EMC Insignia
EMC Insignia provides both hardware and software for a pre-configured backup solution, consisting of EMC Retrospect backup software along with EMC CLARiiON network disk storage. Insignia Solution for Data Protection adds an agent for backing up open files, while Insignia Solution for Exchange adds the EMC Retrospect Exchange Server Agent add-on. The agent protects Exchange open files, and can restore data down to the message level. The network disks in both cases are the EMC CLARiiON AX150 dual controller with five 500Gb SATA II drives. The systems are designed to provide high quality local backup, and most organisations would add tape backup for off-site secure archiving.
The software element of Insignia is Retrospect. This makes it easy to keep track of machines on your network, with wizards to guide you through tasks such as scheduling backups and automatic handling of backups once you’ve assigned a drive for protection. Clients are backed up when they become available on the network, rather than on a fixed schedule. This is especially useful for machines which are only occasionally connected to the network, such as laptops.
Retrospect provides incremental backups for your drives and minimises the amount of wasted space through the use of an automated grooming feature that deletes out-of-date backups. It’s easy to copy backups from the disk system onto tape, and when you do, those backups are protected using AES media encryption. The latest version also integrates with Mozy, an online backup tool that can be used to back up data to an off-site server. Restoring can be done by end users who can browse for their data using a Web browser.
In addition to the Exchange version of Insignia, there’s an SQL Server add-on that will back up SQL Server databases even when they’re in use. Insignia can be used to protect computers running Red Hat Enterprise Linux 4, Novell Linux Desktop 9 and Mac OS X 10.4 Tiger, as well as Windows.
Novastor
NovaNET Backup comes in three versions ranging from Professional, an entry level product for PC and workstation backup, through File 
NovaBACKUP can work with Microsoft's Volume Copy Shadow Service and with
Data Protection Manager.Server to Business Essentials. File Server is the product to choose if you want networked backup of your servers and workstations, while Business Essentials includes back up of Microsoft SQL and Exchange Servers.
The software comes with wizards to help you set up the disks to be backed up, together with a scheduler. NovaNET can be used to back up and recover machines running Windows, Linux, or NetWare, and can back up your data to tape, disk, SAN or NAS. The disk-to-disk backup support is provided as an integrated Virtual Tape Library (VTL). You can also use online backup via FTP and Internet Storage.
The latest version has added disk imaging so that you can take a snapshot of the entire system for use if a major problem occurs. If you need to restore data, you can choose to restore specific files, and you have the choice of overwriting existing files or restoring to an alternative location.
The support for SQL Server and Exchange Server lets you back up their open files while users continue to use the databases, or send and receive emails. NovaBACKUP can also work with Microsoft’s Volume Copy Shadow Service, and Microsoft Data Protection Manager support has been added to the latest version. If you want to back up open files on other operating systems, NovaStor also produces the NovaStor Open File Manager Plug-Ins which let you back up files that are open and locked while in use.
Microsoft
Microsoft Data Protection Manager (DPM) 2007 is
Disaster recovery with O&O
While we all have good intentions when it comes to backing up vital data, it’s easy to forget to do it on a regular basis. The products mentioned elsewhere ensure data is backed up automatically, but machines can still slip through the net and miss the backup window. O&O DriveLED is a package that monitors the health of your hard disks. It runs as a constant background job and will warn you of potential problems so you can back up those vital files before the drive malfunctions.
O&O DriveLED uses SMART (Self Monitoring, Analysis and Reporting Technology) as supported by most modern hard disks. This checks the interface, disk surface and disk mechanics including the read/write heads. When the analysis shows a potential problem, you are warned and can back up the files.
The other products in the O&O range can help you if your backup plans fail and you need to recover data from the original computer rather than from a backup device. O&O FormatRecovery can be used to recover information from hard disks where data has been wrongly deleted, or even where the disk partition has been formatted or removed. You are guided through the recovery by an on-screen Assistant, and the software will recover files even if the data is fragmented, or if directories and configuration information is missing.
O&O DiskRecovery offers similar functionality but searches hard disks, memory cards or digital camera cards at the sector level to find lost files. The program recognises and will restore over 300 file types including Microsoft Word, Excel and Access data files and documents.
If the files that have been deleted are photographs, videos or music files then O&O MediaRecovery is designed specifically to look for multimedia file types. Over 80 file types are recognised and can be recovered from your hard disk or the storage media of your camera or MP3 player. You can preview the files before recovering them to find the particular ones that you want, and the program will recover files even if the storage media has damaged or destroyed them.
O&O RescueBox combines O&O DiskRecovery with O&O UnErase and O&O DriveLED. O&O UnErase is a program for recovering specific files that have been deleted from your hard disk. part of the Microsoft System Center family. DPM will protect documents as well as applications such as Exchange, SQL Server, SharePoint and Microsoft Virtual Server. It does this using Microsoft’s Volume Shadow Copy Service (VSS). This allows you to take a snapshot of all the data stored on a drive, giving you a ‘point-in-time’ backup. VSS also handles open files to ensure they’re included.
If an application is VSS aware, as is Exchange, SharePoint or SQL Server, then VSS can back up data while the application continues to use it. Applications that are not VSS aware are still backed up, but the backup is simply the file in its current status rather than a static copy. In this way, DPM creates and maintains a replica of the data on protected servers, with the replica synchronised at whatever intervals you specify. You can use both disk and tape-based protection, with choices of disk-to-disk, disk-to-tape and disk-to-disk-to-tape.
DPM will look familiar to anyone used to administering Microsoft applications, with copious wizards to help you set up data protection on your systems. You see the data that needs to be protected organised in the same way you’d see it in the original server application, so you see Exchange Storage Groups, for instance, or SQL Server databases, and can select a database for backup rather than having to work out which tables, stored procedures and indexes form a particular database. The same thing is true of virtual machines managed by Virtual Server, and SharePoint farms. Under DPM you select the application ‘item’ to be protected, and DPM then backs up the files that make up that ‘item’. |
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KAY EWBANK
Kay is a database consultant specialising in EIS, financial analysis and GIS systems. While much of her work is based in London, being a consultant gives her the freedom to sail, travel and help out as a part-time sheep farmer
kaye@hardcopymag.com
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