White Paper A New RAID Configuration for Rimage November 2012
Combining RAID 5 and RAID 0 to Reduce the Impact of Hard Drive Failures Rimage is changing the hard drive layout and RAID configurations for its disc publishing products containing embedded computing systems. This new layout reduces the impact of a hard drive failure while maintaining peak system performance. The new hard drive layout is implemented in the Rimage Professional 5410N and Producer 8200N/7200N/6200N systems. Previous Storage Architecture Previously, Rimage utilized a single RAID 0 configuration for Professional and Producer system storage. RAID 0, otherwise known as a striped array without parity, is used when performance is of primary concern. Rimage implemented RAID 0 due to the large amount of disk I/O required to feed multiple recorders as well as staging future jobs to ensure maximum throughput. The 5400N and 6100N systems had RAID 0 implemented across two hard drives and the Producer 7100N and 8100N systems had RAID 0 implemented across three hard drives (Figure 1). A single RAID volume was created utilizing 100% of the disk's capacity; then the RAID volume was broken up into two logical partitions: C: and D:. The C: partition was intentionally quite small, containing the active boot partition, OS and Rimage software. The D: partition contained the rest of the available space and was utilized for temporary storage of images, caching space and the Rimage shared working folder. 5400N and 6100N Systems 7100N and 8100N Systems Figure 1: Previous Rimage RAID architecture 2
Why the Change? In the older Rimage environment and workflow, RAID 0 offered the best system performance. However, it carried a risk as there is no parity information stored in a RAID 0 array. The data from a failed disk could not be regenerated once it was replaced. Losing any one of the hard drives resulted in complete data loss and a non-bootable system. To recover, users were required to start from scratch and reload the OS and software using either Rimage Recovery Disc or a customer s backup image, if one was created. This recovery process was usually painful and time consuming, since any custom settings, computer names, network configurations, third-party software and service packs would need to be recreated manually. Rimage s New Storage Architecture To meet both performance and throughput requirements, as well as to lessen the risks imposed by a RAID 0 configuration, Rimage investigated the possibility of using different RAID configurations. Rimage found that the Intel Rapid Storage Technology RAID controller offers a feature called Matrix RAID. This feature allows Rimage to implement two different RAID types on a single set of physical drives (Figure 2). This solution creates a RAID 5 (striping with parity) volume for the OS, applications, system and boot partitions improving data security and fault tolerance and simplified serviceability while still keeping the RAID 0 (striping w/o parity) volume for caching to maintain the high performance needed for maximum system throughput. 5410N and 6200N Systems 7200N and 8200N Systems Figure 2: New Rimage RAID architecture 3
Same Performance, Improved Recovery From a user's perspective this new hard drive configuration behaves similar to the previous hard drive configuration. Windows Explorer will still list a C: and a D: drive. In Device Manager you will see two physical hard drives. Previous configurations had only one drive in Device Manager with both C: and D: drives listed within it. Volume 1 is the RAID 5 protected volume containing two partitions: a hidden partition and the C: drive. The first partition is the Windows Active System & Recovery partition that did not exist with Embedded XP systems. This partition is a hidden Type 0x27 partition. It contains the master boot code and windows boot manager code used to boot the computer. It does not have any drive letters assigned and is not visible from Windows Explorer. The second partition on the RAID 5 protected volume is the windows boot partition assigned drive letter C:. This partition contains the operating system files and applications. Volume 2 is the RAID 0 non-protected volume containing one partition assigned to drive letter D:. This partition is used to store temporary images and as a caching drive. It also hosts the Rimage shared working folder. One additional physical hard drive has been added to each of the systems to offset a small loss of capacity and performance caused by the addition of the parity information in the RAID 5 array. There are a total of three physical drives in the 5410N and 6200N systems and a total of four physical drives in the 7200N and 8200N systems. Though you may not notice much difference when using the systems, the difference will be quite apparent in the event of a hard drive failure. In that case the C: partition (Volume 1) will remain intact and not result in a non-bootable state. Since it is a RAID 5 volume it can survive the loss of a single physical drive from the array. While all of the data on the D: partition will be lost, this volume only contains the temporary and system caching data, along with the Rimage working folder. It is easy to recover from this, since the critical system and boot information remain intact due to the RAID 5 parity information. Once the failed hard drive has been replaced, the storage controller can rebuild the volume from the parity information on the remaining drives. NOTE: a second drive failure either before or during the rebuild will result in complete data loss, leaving the system in a non-bootable state. 4
D: Partition is for Caching and Working Files Only Although the D: partition has a large amount of storage capacity, this space should only be used as temporary storage. The D: partition is intentionally kept mostly empty to maximize the read/write performance for caching and the work folder. The average data rate of the storage will decrease as the drive fills up. The faster data rates are achieved when the data is being read from or written to the outer portion of the disks. It is best to keep the amount of data stored on the D: drive to a minimum to achieve the best performance and disc burn quality. It is also best practice to run a disk defragment utility on storage volumes with a high number of file writes and deletes. If the D: drive is utilized as general storage space, the Rimage cache files and temporary files used for disc production end up on the slower areas of the disk, impacting throughput and disc burn quality. Keeping drive D: mostly empty and defragmented is the key to optimum performance. In addition, since the D: drive is using RAID 0 (non-parity), any data stored on the D: drive is at risk of being lost and should be backed up. Rimage s new RAID configurations improve the recoverability of the system in the case of a hard drive failure while maintaining the performance that you expect from Rimage publishing systems. By following the file storage and recovery recommendations listed above, your Rimage system will recover even more rapidly, should a drive failure occur. 5
White Paper A New RAID Configuration for Rimage November 2012 2012 Rimage Corporation. All rights reserved. This document is provided for information purposes only and the contents hereof are subject to change without notice. This document is not warranted to be error-free, nor subject to any other warranties or conditions, whether expressed orally or implied in law, including implied warranties and conditions of merchantability or fitness for a particular purpose. We specifically disclaim any liability with respect to this document and no contractual obligations are formed either directly or indirectly by this document. This document may not be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose, without our prior written permission. Rimage is a registered trademark of the Rimage Corporation. All other brand or product names are trademarks of their respective owners and are used without intention of infringement. Blu-ray Disc is a trademark of the Blu-ray Disc Association. RAID-WP028-1013