1 For Small and Medium Businesses Overview May 2008
2 Overview 2 Contents Page 3 Page 6 Page 9 Page 11 Introduction RAID storage Software versus hardware RAID Backup hardware and software Considerations for storage planning Storage Guidelines Home office solutions: Less than 1TB Small solutions: 500GB to 2TB Medium solutions: 2TB to 5TB Large solutions: 5TB to 10TB Internal versus external storage External hard drive considerations Long-term storage media Storage Connections How are you connecting your storage? Higher capacity RAID or SAN solutions RAID Types RAID principles Striping Mirroring Parity
3 Overview 3 Introduction If you re in the business of creating or distributing digital content, your data is growing fast. High-resolution photography, digital video footage, and expanding media asset databases can require terabytes of storage. At the same time, data protection and nearinstant data access are crucial to your operation. Tip: Once your storage requirements grow beyond a single drive, keep your operating system and applications on a separate drive for fastest performance and best protection. What should you store? Back up: Home directory, , documents, original assets, project files, movies, pictures, music, library (with the exception of caches and logs) Archive: Project files, original assets, documents, financial data, , business-related ichat messages Don t need to back up: Applications, render files, cache files, system folder (assuming you have the original installation discs) Note: An offsite copy refers to a hard drive, tape, or DVD that s located at home or in a safe instead of at the office. Insurance companies typically want you to keep data archived offsite. Do you have a strategy for data storage, backup, and archive? This document provides guidelines, recommendations, tips, and valuable information to help you make decisions that are right for your business. First, here are some definitions and comments. Storage involves saving your documents, media files, and other content to a hard drive or other device so that you can access them regularly. Most of the time, storage happens without any thought on your part. When you save a document to your desktop, you are storing it on your computer s hard drive. When you receive an message, it s downloaded and stored in a folder on your hard drive. When you burn photos to a DVD, the DVD is storing your photo files. However, as you accumulate more and more data, finding the files you need and backing up your important files can be difficult. Certain storage methods make finding and backing up data easy, while others render these tasks nearly impossible. Backup is a strategy wherein a primary copy of your data resides in one location, such as the internal hard drive, and a secondary backup copy is close at hand. They might be in the same physical location (such as your office), but not on the same storage device. Frequent backup protects the data you use or might use every day. Whether messages, documents, or media files, this data is essential to your business operations. Backup does not mean moving your data to another drive or device to free up space on the main drive. Even after you ve made the backup copy, you must keep the original or one other copy somewhere else. If your original is lost due to drive failure or accidental deletion (ever done a Save instead of a Save As?), you can connect, insert, or attach your backup volume and copy the file back to its original location. This is also called an online, or near-online, backup. Archive is long-term storage, also known as offline backup. Archived data is crucial to your business for legal, insurance, or other reasons, but it s no longer changing and doesn t need to be accessible on a regular basis. It might be a project that s been completed and signed off by a client or a document that is no longer being updated. DVDs, external hard drives, and tape cartridges are commonly used to archive. Larger, more robust archives use a combination of hard drives and tape-based solutions for a powerful mix of speed and reliability. How does archiving differ from backing up? Backup data is stored in an easily accessible location, while archived data can be stored near or far away since you ll access these files much less often.
4 Overview 4 RAID storage As your storage requirements grow, the obvious solution is to add more hard drives. It s attractive too. Prices are falling so drastically that the latest high-capacity drives barely make a dent in your budget. Why not pick up a new one every few months? The problem is, there s no eﬃcient way to manage, retrieve, and back up your data as those hard drives stack up. Imagine that you have 20 external hard drives (that may all look the same), and you want to find a single asset or group of assets. Do you plug in every single drive and search it? Do you keep and update a list of which assets are on each drive? Or do you resort to Post-it notes slapped on all your drives? And in the case of a drive failure, how long will it take to restore all of your data? Mac Pro Xserve Promise This is where RAID comes in. Redundant Array of Independent Drives (RAID) allows you to use the storage space of multiple drives at one time. This array appears as a single volume on the computer. Using hardware or software RAID (meaning that either dedicated hardware or the operating system will handle the load), you can configure your storage to deliver diﬀerent levels of performance, capacity, and redundancy. The most common are RAID levels 0, 1, and 5. It s important to understand that RAID is not a backup solution. There s a diﬀerence between redundancy and backup. Redundancy is a RAID feature that keeps information about your data. This information is used to re-create your files and documents should one of the drives fail. It s not a backup copy of your files, but a set of instructions on how to rebuild them. The downside is that if you delete, overwrite, or corrupt your files, the instructions for rebuilding them are lost. This is also one of the ways redundancy diﬀers from backup. A file that s backed up can be restored if you delete the original. Redundancy is invaluable in environments where downtime is not an option. With a backup alone, if you lose data, you can t work until the data is restored. This can take a while if you lose an entire hard drive. Additionally, any data you ve created since your last backup will be lost. RAID, on the other hand, will rebuild your data on the fly, which means you can stay working. It s a failover system that provides data despite a failure. It s best to store your data using RAID. Be sure to back up as well to cover you in the event of hardware failure or software data loss. Read on to learn more about how RAID can help you prepare for future storage needs. Software versus hardware RAID Tip: For the ultimate in data protection and enhanced performance, both the Xserve and the Mac Pro may be configured with internal hardware RAID cards. Both cards feature 256MB of RAID cache, a 72-hour cache protecting battery, and hardware RAID levels 0, 1, and 5. The Mac Pro RAID card provides up to 304MB/s, while the Xserve RAID card delivers up to 318MB/s. RAID functionality can be implemented in hardware or software. Software RAID, included in Mac OS X and Mac OS X Server, enables you to stripe or mirror disk arrays for enhanced performance or greater data protection. However, it s not practical for implementing RAID levels that use parity for higher availability and drive eﬃciency. Parity RAID levels, such as RAID 3 and 5, involve compute-intensive operations that can overtax the system processor, aﬀecting overall performance. A hardware RAID controller prevents this bottleneck and delivers maximum throughput while providing the highest level of fault tolerance.
5 Overview 5 Backup hardware and software Are you tired of copying files and folders manually each time you want to back up? Choose a software solution that automates your backup plan to remove the drudgery, while helping to ensure your important data is safe and sound. The best backup software allows you to set a regular backup time say, every Thursday at noon and then forget about it. Backup basics Some software solutions are optimized for backing up media and other files. Others are designed to copy the entire contents of your hard drive, applications and all. No matter what you use, make sure the software allows you to back up as an administrator so you don t have problems with file privileges. Most software products have you covered, but it s a good idea to check. Performance and protection What else should you look for in a backup application? With incremental backup, only data that has changed is backed up, reducing backup time and saving harddrive space. Compression also saves space, and encryption protects your documents from unauthorized access. Most backup software will even check each copied file to verify that it was backed up correctly. And for those occasions when you actually lose backed-up data, you ll be relieved to have software that restores it, putting the data where it belongs quickly and easily. Tip: Once you ve made a decision and have your backup software, do a practice restore. It ll help you become familiar with how the software restores lost data should you ever need to use the process. Advanced solutions The more data you back up, the less practical DVDs become. Tape-based backup provides much higher capacity and faster speed. Using a combination of auto-loading hardware and scheduled backup software, you can automate the process of archiving data. This is far more streamlined than manually loading hundreds of DVDs. As you step up to tape solutions for archiving data, make sure your backup software supports the tape interface you re using, for example, Fibre Channel or SCSI. If you intend to set up a storage area network (SAN) using Apple s Xsan you ll want an application with SAN support. Considerations for storage planning How much is your data worth to your business? How much storage will you need to consolidate 18 months from now? How are you going to find and back up all that data? What is your current backup and archive plan? How much of your data can and should be backed up? How frequently are you producing new data or updating existing data? Should you back up daily, weekly, or monthly?
6 Overview 6 Storage Guidelines Tip: If you have space inside your computer for more hard drives, use it. A Mac Pro has four hard drive bays, and an Xserve can hold three Apple Drive Modules. These drive bays are well cooled, they provide great transfer speeds, and you ve already paid for the enclosure. A Mac Pro or Xserve with one hard drive takes up no more room than a fully loaded system, while each additional external drive requires another cable, another AC adapter, and more room on your desktop. The storage requirements of your business are largely driven by how much data you create or update on a regular basis. Whether you re a large operation or a sole proprietor, you ll want to consider the following: How much data do you need to have online, or instantly accessible, all the time? How much data have you created this year? Spotlight can find all files created in the last 365 days. How much will your data requirements grow? Even if your company isn t growing, consider that you ll most likely create 30 to 50 percent more data in the next year. After determining how many gigabytes or terabytes of data you ll have in the next 18 months, use the following guidelines to scope storage, backup, and archive solutions that are realistic for your business. Home oﬃce solutions: Less than 1TB Storage: Your computer s internal hard disk is usually the primary or only storage device required for your home oﬃce. Additional FireWire or USB hard drives can be added as your storage needs grow. Backup: Time Machine in Mac OS X version 10.5 Leopard is an excellent solution for one-click, continuous backup. It works with attached FireWire or USB hard drives, or wirelessly with Time Capsule. Time Capsule is a full-featured n Wi-Fi base station that includes a 500GB or 1TB server-grade hard drive designed to work with Time Machine in Leopard. Archive: You ll need to archive important data and projects on an external hard drive that s separate from your backup and stored in a diﬀerent location. Small solutions: 500GB to 2TB Storage: The internal storage of a Mac Pro (4TB) or Xserve (3TB) should be suﬃcient. You can choose to consolidate your data using RAID or to store diﬀerent data on each individual drive. Now you have the ability to configure a Mac Pro or an Xserve with an internal hardware RAID card for RAID levels 0, 1, and 5. Whether you re storing photography, video, or your mail server, the Mac Pro and Xserve with an internal hardware RAID card can protect your data without external drive enclosures, power bricks, or cables. Backup: If your storage needs fall into the lower end of this spectrum, you can probably back up to a separate internal drive. But as those needs grow, you ll most likely want to rely on an external drive for backup. This also gives you the flexibility to move your backup to a secure oﬀsite location.
7 Overview 7 Archive: You ll need to archive your data on an external hard drive that s separate from your backup. There are also aﬀordable tape solutions. Depending on how much you need to archive, even DVD media may be suﬃcient. Medium solutions: 2TB to 5TB Storage: As you begin to exceed the storage capacity of your computer, it s time to add external storage to the system. An easy, low-cost solution is to use software RAID in Mac OS X to combine multiple external drives. But for better performance and greater scalability as you continue to create digital content, you may prefer a hardware RAID solution, such as the Promise VTrak E-Class RAID subsystem. Also be sure your storage solution has enough space for the content you re going to create in the future, not just for what you have today. Backup: Start by using external storage in addition to the primary storage devices. An even better solution is RAID, such as the Promise VTrak E-Class RAID subsystem. Since it features two independent RAID controllers, you can use one volume for main storage and the other for backup. Archive: To archive this much data, you ll want to consider a robust tape solution. Multiple external hard drives may work as well, though they present some serious physical management challenges. Don t even consider DVDs. Large solutions: 5TB to 10TB Storage: A high-capacity RAID solution gives you plenty of external storage that scales well without compromising performance. Backup: This is where Xserve RAID is the perfect solution for both storage and backup. It allows you to use a combination of software and hardware RAID for an ideal balance of performance and protection. Archive: It s time to invest in a tape solution no question about it. In fact, with this much data, consider an autoloading tape library system, which allows you to go from disk to disk to tape for storage, backup, and archive using an integrated tiered storage solution. And with automatic backup and archive software, you won t have to worry about loading the tape. Internal versus external storage Tip: Hard drives are made to spin. If you re using a backup drive that isn t connected to the computer, be sure to turn it on regularly. This gets the motor spinning and the head moving, which in turn prevents issues related to sticktion a breakdown of lubricant that can cause the metal surface of the disk to stop or stick. Powering up the drive also allows your system to identify and repair any errors that may have been introduced while the disk was inactive. Internal storage lives inside your computer or server on the internal hard drive (or drives) that comes with your system. Since internal hard drives connect directly to the system controller, typically using a Serial ATA (SATA) interface, data transfers are very fast. And because there are fewer components and no enclosure, internal storage is more reliable, more compact, and less expensive than external solutions. External storage relies on hard drives housed in self-contained enclosures outside the computer. They usually connect to your system via USB or FireWire, though it s now possible to find drives with esata connections. External storage is easy to set up just plug in the hard drives and they become available. The limitation on internal storage is space: If you can no longer add internal storage, it s time to consider using high-quality external storage.
8 Overview 8 External hard drive considerations Not all storage is created equal. In addition to capacity and price, keep an eye on the following attributes. Technology: Make sure that the manufacturer is using the latest and most reliable components (and that they include the cables you ll need to connect the drive to your system). A product that costs far less money could cost you far more in data loss. For example, a well-protected (and more expensive) physical mount will protect the hard disk from shock and resulting data loss. Interface and rotational speed: Rotational speed describes how fast data is being read/written/retrieved from the drive. If your drive s rotational speed is extremely slow, it doesn t matter how fast the data transfer protocol is. Before the transfer cable sees the data, the drive has to find it. Enclosures: As hard drives spin and access data, they can get hot. Metal dissipates heat well, keeping the hard disk cool and decreasing the risk of drive failure. A plastic enclosure without fans or vents might not cool itself as well as a metal enclosure (which has both). Long-term storage media Tape (capacity: 80GB to 320GB for VXA; 200GB to 800GB for LTO) Tape-based storage uses magnetic tape stored in cartridges, which can be placed in autoloading devices that change tapes automatically when needed. This allows you to create a tape library that contains all your backup data. In addition to capacity considerations, you should know how fast your transfers need to be. For example, transferring 1TB of data onto tape can take anywhere from three hours to two days. Tip: If you must use DVDs for archiving, consider DVD+R over DVD-R. CDs and DVDs (capacity: 700MB for CDs; 4.7GB for DVDs) Look for gold- or silver-based media. The write speed of the optical drive determines transfer speeds. Keep your media in a safe environment, protected from moisture, sunlight, and extreme temperatures. Avoid using Sharpie markers and labels for longterm storage, as they contain acids that can eat through CD and DVD media. Neither CDs nor DVDs are recommended for large archives. More than 200 DVDs are needed to back up just 1TB of data.
9 Overview 9 Storage Connections Before choosing a storage solution, you ll need to determine how the storage will be connected to your computer, server, or network. Each storage interface USB, FireWire, esata, Ethernet, SCSI, SAS, and Fibre Channel has its own advantages and disadvantages. Your deployment plans will help you determine the best fit. How are you connecting your storage? Direct-attached storage (DAS) DAS connects directly to your computer. It s the easiest and most inexpensive solution just attach a FireWire or USB drive to your system. Keep in mind that this configuration doesn t allow users on other systems to share your files or storage space. It s truly a single-system solution. Network-attached storage (NAS) NAS is available to multiple computers on the network using file-sharing protocols. A file server most often a dedicated computer acts as a traffic cop, ensuring that multiple people don t write to files at the same time. This is a big step up from DAS. However, since NAS relies on the Ethernet network, large transfers and many transactions can slow down local network activities. Tip for professionals USB versus FireWire: While its theoretical transfer speed is faster than FireWire, USB handles data transfers less efficiently. For this reason, you may prefer FireWire if you ll be constantly accessing data on the drive. Use USB only for backup or for storing data that you don t need to access frequently. Storage area network (SAN) SAN is a separate network used primarily for transferring data between computers and storage devices. With SAN, data transmission for backups, restores, and mirroring doesn t interfere with the local network. This makes it easier to administer and frees up the local network s bandwidth for critical business functions. SAN is the most scalable storage configuration. USB 2.0 (480Mb/s) USB has become the most popular interface for DAS devices. Thanks to high theoretical transfer speed and relatively low cost, it s an ideal solution for many small-office scenarios. And with built-in drivers on both the Mac and PC, USB provides lots of flexibility. FireWire 400 and 800 (400Mb/s and 800Mb/s) FireWire 400 and 800 are popular storage protocols for desktop and portable devices. Because FireWire transfers data in a highly efficient way, it s ideal for transferring video content or any other data that s constantly being read and written. Unlike USB, FireWire drives can be daisy-chained with minimal performance loss. By connecting one drive to the next, you can attach multiple drives to a single port on your computer.
10 Overview 10 esata (3Gb/s) esata is an emerging connection interface that delivers extremely high transfer speeds. In fact, it s so fast that the speed of the physical disk often becomes the bottleneck instead of the connection. To take full advantage of esata, use it in a RAID deployment. Since esata uses the same technology as the internal hard drive, it works well as an external media drive for desktop systems. esata doesn t work as well for portable systems because unlike FireWire and USB, it requires an external power supply. Ethernet (100Mb/s or 1Gb/s) Ethernet is the communications protocol for nearly everyone s local network. Easy to set up and use, it works well for accessing and transferring small files (less than 100MB) that are constantly being used. However, if you use the network for simultaneous access to a shared resource, such as a network-based hard drive, network performance will start to slow. These ineﬃciencies will be especially pronounced with video content and other extremely large files. Higher capacity RAID or SAN solutions SCSI (320MB/s) SCSI is a popular interface for tape backup, delivering high-quality transfers at very high speeds. It works well for DAS but can be somewhat complex to configure in a NAS or SAN solution. As other alternatives become more popular, it s harder to find SCSI-based hard drives designed for use with desktop systems; most are intended for use with servers and in other enterprise environments. Tip for video: When you transfer video content, it s crucial that all the data arrives at a precise time. For this reason, FireWire or Fibre Channel is recommended for video storage. Fibre Channel (2Gb/s or 4Gb/s) Fibre Channel provides some of the fastest transfers available, making it a great solution for huge files, such as HD video or large Adobe Photoshop documents. While Fibre Channel and Ethernet can both be deployed over long distances between oﬃce buildings, for example Fibre Channel has a distinct advantage. Its hardware manages the data transfer, so there s no extra load on the processor as there is with Ethernet. You can connect Fibre Channel storage directly to a computer (DAS) or to a networked file server (NAS). For large deployments, you ll see a significant performance boost by creating a separate network specifically for storage (SAN).
11 Overview 11 RAID Types RAID levels RAID technology can be applied in different configurations each offering a unique balance of performance, data protection, and storage efficiency. Xserve RAID supports the most popular RAID levels, so you can select the best configuration for your application and budget. RAID 0: Striping. Lays down data in stripes across an array of drives for exceptional I/O performance, but with no data protection. RAID 1: Mirroring. Writes identical copies of data on a pair of disks for total redundancy, but with limited performance and inefficient use of drives. RAID 3: Striping with parity. Stripes data across two or more drives and stores parity data on a dedicated drive, providing data redundancy and faster performance than a single drive. RAID 5: Striping with distributed parity. Distributes data and parity information across an array for high throughput, good redundancy, and efficient use of drives. RAID 0+1: Striping over mirroring. Stripes data across pairs of mirrored drives for performance and redundancy. RAID principles RAID technology is based on the practices of striping to improve storage performance, and mirroring and parity to provide redundancy for increased data protection. Most RAID configurations, or RAID levels, combine these techniques to provide a balance of data protection and performance. Striping As the name implies, striping divides a logical drive into data blocks, or stripes, that are distributed across the array of physical drives. Data is then laid down according to the stripe paths so that each file is spread across multiple drives. Striping a set of disks greatly improves overall storage performance because each drive operates concurrently. While one drive is writing or reading a data block, another is seeking the next block in parallel. However, striping alone, known as RAID level 0, offers no data protection. Stripe 1 Stripe 4 Stripe 7 Stripe 10 Drive striping Stripe 2 Stripe 5 Stripe 8 Stripe 11 Disk 1 Disk 2 Stripe 3 Stripe 6 Stripe 9 Stripe 12 Disk 3 Striping breaks a single file into data blocks and distributes it across two or more drives. RAID 10, 30, and 50: Striping over RAID 1, 3, and 5. Uses hardware RAID to create two or more sets in RAID level 1, 3, or 5, and software RAID to stripe across the sets. This creates a single data volume with the best balance of performance and data protection.
12 Overview 12 Mirroring The simplest method of achieving data redundancy, mirroring involves writing identical copies of all data to a pair of physical drives. This results in very high data reliability if one drive fails, the data is still available on the remaining disk drive. However, you ll get only 50 percent storage efficiency because two physical drives are required to achieve a single drive s capacity. Mirroring alone is known as RAID level 1. Mirrored pair Striped pairs Mirrored pair Stripe 1 Stripe 1 Stripe 2 Stripe 2 Stripe 3 Stripe 5 = Stripe 3 Stripe 5 Stripe 4 Stripe 6 = Stripe 4 Stripe 6 Stripe 7 Stripe 7 Stripe 8 Stripe 8 Disk 1 Disk 2 Disk 3 Disk 4 Mirrored drives contain identical sets of data for total redundancy. Parity A more sophisticated method of creating redundancy, parity provides data protection for an array of drives without requiring complete duplication of the drive contents. Parity information can be used along with the data on the surviving drives to reconstruct the contents of a failed drive. The parity data can be stored on a dedicated drive, as in RAID 3, or distributed across an array of drives, as in RAID 5. In either case, parity provides much greater storage efficiency than mirroring up to 85 percent for a set of seven drives. Since parity involves calculating complex algorithms, it usually requires a dedicated hardware RAID processor and shouldn t be implemented in software RAID due to tremendous performance degradation. Parity generation Stripe 1 Stripe 4 Stripe 7 Stripe 10 Stripe 2 Stripe 5 Stripe 8 Stripe 11 Stripe 3 Parity 1 3 Stripe 6 Parity 4 6 Stripe 9 Parity 7 9 Stripe 12 Parity Disk 1 Disk 2 Disk 3 Disk 4 RAID 3 stripes data across two or more drives and stores parity data on a dedicated drive. Parity generation Stripe 1 Stripe 4 Stripe 7 Parity Stripe 2 Stripe 3 Parity 1 3 Stripe 5 Parity 4 6 Stripe 6 Parity 7 9 Stripe 10 Stripe 9 Stripe 11 Stripe 9 Stripe Disk 1 Disk 2 Disk 3 Disk 4 RAID 5 distributes data and parity information across all the drives in an array Apple Inc. All rights reserved. Apple, the Apple logo, FireWire, Leopard, Mac, Mac OS, Xsan, and Xserve are trademarks of Apple Inc., registered in the U.S. and other countries. Adobe is a trademark or registered trademark of Adobe Systems Incorporated in the U.S. and/or other countries. Other product and company names mentioned herein may be trademarks of their respective companies. May 2008 L371597A