Figure 1. With hardware acceleration for RAID 5 and 6 operations plus dedicated memory for caching, the e offer the ultimate performance for connectivity with external SAS disk enclosures for ThinkSystem servers. This feature boosts the performance of applications with a highly random data storage access pattern, such as transactional databases.
To avoid the possibility of data loss or corruption during a power or server failure, flash cache protection technology transfers the contents of the DRAM cache to NAND flash using power from the offload power module. Auto-resume uses non-volatile RAM NVRAM to save the rebuild progress during a host reboot or power failure to automatically resume from the last checkpoint. Auto-resume ensures that data integrity is maintained throughout the process. The card supports a number of features that can be implemented without rebooting the server.
Applications, such as email and web server, benefit from avoiding downtime during the transition. Online Capacity Expansion OCE allows the capacity of a virtual disk to be expanded by adding new physical disks or making use of unused space on existing disks, without requiring a reboot.
System availability and application functionality remain unaffected. Fast initialization quickly writes zeros to the first and last sectors of the virtual drive. This feature allows you to immediately start writing data to the virtual drive while the initialization is running in the background.
Consistency check verifies that all stripes in a virtual disk with a redundant RAID level are consistent. Consistency checks can be scheduled to take place periodically. Management tools provide convenience for the configuration of logical volumes and alerting when errors have occurred or are about to occur. Patrol read is a background sentry service that pro-actively discovers and corrects media defects bad sectors that arise normally as a disk drive ages.
The service issues a series of verify commands, and if a bad block is discovered, the card's firmware uses RAID algorithms to re-create the missing data and remap the sector to a good sector. The task is interruptible based on controller activity and host operations.
The firmware also provides an interface where the patrol read task can be initiated, set up for continuous operation, and terminated from a management application. Patrol read can be activated by a manual command or automatically. A hot spare rebuilds data from all virtual disks within the disk group in which it is configured. You can define a physical disk as a hot spare to replace a failed drive. Hot spares can be configured as either global or dedicated. A global hot spare allows any physical drive to be designated as a hot spare.
A dedicated hot spare allows the user to assign a hot spare drive to a particular array of the same drive type. Drive roaming occurs when the physical disks are changed to different ports on the same controller. Because each drive contains both data and parity, numerous writes can take place concurrently. Table 9 provides an overview of RAID 5.
Figure 9 provides a graphic example of a RAID 5 drive group. With two independent parity blocks, RAID 6 can survive. RAID 6 provides a high. In the case of a failure of one drive or two drives in a virtual drive, the RAID controller uses the parity blocks to re-create all of the missing information. If two drives in a RAID 6 virtual drive fail, two drive rebuilds are required, one for each drive.
These rebuilds do not occur at the same time. The controller rebuilds one failed drive, and then the other failed drive. Table 10 provides an overview of a RAID 6 drive group. Not well-suited to tasks requiring a lot of writes. A RAID 6 virtual drive has to. Figure 10 shows a RAID 6 data layout. The second set of parity drives is denoted by Q. A RAID 00 drive group is a spanned drive group that creates a striped set from a series. RAID 00 does not provide any data redundancy, but, along with.
RAID 00 breaks up data into. The size of each data segment is determined by the stripe size. RAID 00 offers high bandwidth. RAID 00 involves no parity calculations to complicate the write operation.
This situation makes RAID 00 ideal for applications that require high bandwidth but do not require fault tolerance. Table 11 provides an overview of RAID Figure 11 provides a graphic example of a RAID 00 drive group. RAID 10 breaks up data into smaller blocks and then mirrors the blocks of data. The first RAID 1 drive in each drive group then duplicates its. The size of each block is determined by the stripe size. Spanning is used because one virtual drive is defined across more than one drive group.
Data is striped across drive groups to increase performance by enabling access to multiple drive groups simultaneously. If drive failures occur, less than total drive capacity is available. RAID 10 supports a maximum of 8 spans, with a maximum of 32 drives per span. You must use an even number of drives in each RAID 10 virtual drive in the span. In Figure 12 , virtual drive 0 is created by distributing data across four drive groups drive groups 0 through 3.
RAID 50 includes both parity. RAID 50 is best implemented on two. RAID 5 breaks up data into smaller blocks, calculates parity by performing an exclusive-or on the blocks and then writes the blocks of data and parity to each drive in the drive group. The size of each block is determined by the stripe size parameter, which is set during the creation of the RAID set. RAID level 50 can support up to 8 spans and tolerate up to 8 drive failures, though less than total drive capacity is available.
Though multiple drive failures can be tolerated, only one drive failure can be tolerated in each RAID 5 level drive group. RAID 6 supports two independent parity. A RAID 60 virtual drive can survive the loss of two drives in each of the. RAID 6 sets without losing data. RAID 6 breaks up data into smaller blocks, calculates parity by performing an exclusive-or on the blocks, and then writes the blocks of data and parity to each drive in the drive group. RAID 60 can support up to 8 spans and tolerate up to 16 drive failures, though less than total drive capacity is available.
Two drive failures can be tolerated in each RAID 6 level drive group. Figure 14 shows a RAID 60 data layout. You cannot configure a virtual drive that optimizes all three factors, but it is easy to. For example, RAID 1 mirroring provides excellent fault tolerance, but. The following subsections describe how to use the RAID levels to maximize virtual.
Fault tolerance is achieved through the ability to perform automatic and transparent. A hot spare drive is an unused online. After the hot spare is automatically moved into the RAID drive group, the failed drive is automatically rebuilt on the spare drive. A hot swap is the manual substitution of a replacement unit in a disk subsystem for a defective one, where the substitution can be performed while the subsystem is running hot swap drives.
The RAID drive group continues to handle requests while the rebuild occurs, providing a high degree of fault tolerance and zero downtime. All data is lost if any drive fails. Disk striping writes data across multiple drives instead of just one drive. It involves partitioning each drive storage space into stripes that can vary in size. RAID 0 is ideal for applications that require high performance but do not require fault tolerance.
If one drive fails, the contents of the other drive in the drive group can be used to run the system and reconstruct the failed drive. The primary advantage of disk mirroring is that it provides percent data redundancy. Because the contents of the drive are completely written to a second drive, no data is lost if one of the drives fails.
Both drives contain the same data at all times. RAID 1 is ideal for any application that requires fault tolerance and minimal capacity. Parity provides redundancy for one drive failure without duplicating the contents of entire drives. If a drive fails, the RAID controller uses the parity data to reconstruct all missing information. In RAID 5, this method is applied to entire drives or stripes across all drives in a drive group.
Using distributed parity, RAID 5 offers fault tolerance with limited overhead. RAID 6 can sustain two drive failures and still maintain data integrity. Parity provides redundancy for two drive failures without duplicating the contents of entire drives.
In RAID 6, this method is applied to entire drives or stripes across all of the drives in a drive group. Using distributed parity, RAID 6 offers fault tolerance with limited overhead. All data in a virtual drive is lost if any drive in that virtual drive fails. RAID 00 is ideal for applications that require high bandwidth but do not require fault tolerance. RAID 10 works well for any environment that requires the percent redundancy offered by mirrored drive groups.
RAID 10 can sustain a drive failure in each mirrored drive group and maintain data integrity. RAID 50 includes both parity and disk striping across multiple drives. If a drive fails, the RAID controller uses the parity data to re-create all missing information. It provides the highest level of protection against drive failures of all of the RAID levels. RAID 60 includes both parity and disk striping across multiple drives.
The RAID drive group appears to the. Table 16 describes the performance for each RAID level. RAID 0 breaks up data into smaller blocks and then writes a block to each drive in the drive group. It involves partitioning each drive storage space into stripes that can vary in size from 8 KB to KB. Disk striping enhances performance because multiple drives are accessed simultaneously. Performance is impaired during drive rebuilds. Use this RAID level for any application that requires high read request rates, but low write request rates, such as transaction processing applications, because each drive can read and write independently.
In addition, robust caching algorithms and hardware-based exclusive-or assist make RAID 5 performance exceptional in many different environments.
Drive performance is reduced when a drive is being rebuilt. Clustering can also reduce drive performance. Environments with few processes do not perform as well because the RAID overhead is not offset by the performance gains in handling simultaneous processes. It provides high data throughput, data redundancy, and very good performance. However, RAID 6 is not well suited to tasks requiring a lot of writes. A RAID 6 virtual drive has to generate two sets of parity data for each write operation, which results in a significant decrease in performance during writes.
Drive performance is reduced during a drive rebuild. RAID 00 breaks up data into smaller blocks and then writes a block to each drive in the drive groups. Striping involves partitioning each drive storage space into stripes that can vary in size from 8 KB to KB.
Spanning increases the capacity of the virtual drive and improves performance by doubling the number of spindles. The system performance improves as the number of spans increases. The maximum number of spans is 8. RAID 60 is not well suited to tasks requiring a lot of writes. A RAID 60 virtual drive has to generate two sets of parity data for each write operation, which results in a significant decrease in performance during writes. RAID 5, which provides redundancy for one drive failure without duplicating the contents of entire drives, requires less space than RAID 1.
Table 17 explains the effects of the RAID levels on storage capacity. RAID 0 provides maximum storage capacity for a given set of drives. The usable capacity of a RAID 0 array is equal to the number of drives in the array into the capacity of the smallest drive in the array. This situation is expensive because each drive in the system must be duplicated.
The usable capacity of a RAID 1 array is equal to the capacity of the smaller of the two drives in the array. The usable capacity of a RAID 5 array is equal to the number of drives in the array, minus one, into the capacity of the smallest drive in the array. However, it requires extra capacity because it uses two parity blocks per stripe.
This makes RAID 60 more expensive to implement. The usable capacity of a RAID 6 array is equal to the number of drives in the array, minus two, into the capacity of the smallest drive in the array. RAID 00 provides maximum storage capacity for a given set of drives. RAID 10 works well for medium-sized databases or any environment that requires a higher degree of fault tolerance and moderate-to-medium capacity.
Disk spanning allows multiple drives to function like one large drive. Spanning overcomes lack of disk space and simplifies storage management by combining existing resources or adding relatively inexpensive resources. This RAID level works best when used with data that requires medium to large capacity. However, it requires extra capacity because a RAID 60 virtual drive has to generate two sets of parity data for each write operation.
This situation makes RAID 60 more expensive to implement. Data availability without downtime is essential for many types of data processing and.
Businesses want to avoid the financial costs and customer frustration. RAID helps you maintain data availability and avoid. RAID offers several features, such as. The following subsections describe these features. A replacement drive must be at least as large as the drive it replaces. Spare drives. A hot swap is the manual substitution of a replacement unit in a disk subsystem for a.
The backplane and enclosure must support. Hot spare drives are drives that power up along with the RAID drives and operate in a. Standby state. If a drive used in a RAID virtual drive fails, a hot spare automatically takes. Hot spares can be. NOTE: If a rebuild to a hot spare fails for any reason, the hot spare drive will be marked. If a drive fails in a drive group that is configured as a RAID 1, 5, 6, 10, 50, or 60 virtual. If you have configured hot.
Manual rebuild is necessary if hot spares with enough capacity to rebuild the failed. Each type of data stored in the disk subsystem has a different frequency of read and write activity.
If you know the data access requirements, you can more successfully determine a strategy for optimizing the disk subsystem capacity, availability, and performance. Servers that support video-on-demand typically read the data often, but write data infrequently. Both the read and write operations tend to be long.
Data stored on a general-purpose file server involves relatively short read and write operations with relatively small files. The number of drives in a drive group determines the RAID levels that can be supported.
Only one RAID level can be assigned to each virtual drive. Important factors to consider when creating RAID drive groups include availability, performance, and capacity. Define the major purpose of the drive group by answering questions related to these factors, such as the following, which are followed by suggested RAID levels for each situation:. Use RAID 5, 6, 10, 50, or Use RAID 1, 5, 6, 10, 50, or Use RAID 0 or Use RAID 0, 00, or Fill out Table 18 to help you plan the drive group configuration.
Rank the requirements for your drive group, such as storage space and data redundancy, in order of importance, and then review the suggested RAID levels.
SafeStore encryption services supports local key management. The SafeStore Disk Encryption service offers the ability to encrypt data on drives and. This solution provides data.
With self-encrypting drives, if. Any encryption solution requires management of the encryption keys. The security. You can use. In addition, SafeStore local key management removes the administrator from most of the daily tasks of securing data, thereby reducing user error and decreasing the risk of data loss.
Also, SafeStore local key management supports instant secure erase of drives that permanently removes data when repurposing or decommissioning drives. These services provide a much more secure level of data erasure than other common erasure methods, such as overwriting or degaussing. Table 19 describes the terminology related to the SafeStore encryption feature. The RAID configuration is keyed to a user password. The password must be provided on system boot to.
A blob is created by encrypting a keys using another key. There are two types of blob in the system —. You need to provide the controller with a lock key if the controller is replaced or if you choose to migrate. An optional authenticated mode is supported in which you must provide a password on each boot to. Firmware uses the user password to encrypt. Re-provisioning disables the security system of a device. For a controller, it involves destroying the. For SafeStore encrypted drives, when the drive lock key is deleted, the drive is unlocked and.
This situation does not apply to controller-encrypted drives,. See Section 3. Instant Secure Erase , for information about the instant secure erase feature. A key based on a user-provided string. The controller uses the security key to lock and unlock access to the. This key is encrypted into the security key blob and stored on the controller. If the. You must take all precautions to never lose the. This mode allows controller to boot and unlock access to user configuration without user intervention.
The controller uses the volume encryption keys to encrypt data when a controller-encrypted virtual disk is. These keys are not available to the user. The firmware uses a unique bit key for each virtual.
You can enable security on the controller. After you enable security, you have the. There are three procedures you can perform to create secure virtual drives using a security key:. If you have. The controller provides a default identifier for you. You can use the default setting or. You can choose a. The password provides additional security. The password should be different from the. You can select a setting in the utilities so that you must enter the password.
When you use the specified security key identifier, security key, and password, security. You can change the security settings on the controller, and you have the option to. If you have previously. You can perform three procedures to change the security settings on the controller:. See Section 4. If you plan to change the security. You can select whether you want to keep the current security key identifier or enter a. To change the security key identifier, enter a new security key identifier.
To change the. To keep the existing password, enter the current. If you choose this option, you must enter the password whenever you boot. This procedure updates the existing configuration on the controller to use the new. You can create a secure virtual drive and set its parameters as desired.
To create a. You can select either simple. If you select simple configuration, select the redundancy type and drive security. See Section 8. After the drive group is secured, you cannot remove the security without deleting the virtual drives.
You can import unsecured or unlocked configurations when security is disabled. A foreign configuration is a RAID configuration that already exists on a replacement set of drives that you install in a computer system. To import a foreign configuration, you must first enable security to allow importation of.
If the drives are locked and the controller security is disabled, you. Only unlocked drives can be imported when security. After you enable the security, you can import the locked drives. To import the locked.
Verify whether any. If there are. After all of the drives. Instant Secure Erase is a feature used to erase data from encrypted drives. After the. All encrypted drives, whether locked or unlocked, always have an encryption key. This key is set by the drive and is always active. When the drive is unlocked, the data to host from the drive on reads and from the host to the drive cache on writes is always provided. However, when resting on the drive platters, the data is always encrypted by the drive.
Welcome to ManualMachine. We have sent a verification link to to complete your registration. Log In Sign Up. Forgot password? Enter your email address and check your inbox. Please check your email for further instructions. Enter a new password. Other features such as FastPath and SafeStore are described in other chapters of this guide. They are an ideal RAID solution for the internal storage of workgroup, departmental, and enterprise systems.
This helps to share resources more efficiently and lowers the cost. This feature is configurable and can be disabled. Dimmer Switch III - This new feature spins down any Logical Disk after 30 minutes of inactivity, by default, if the array can be spun up within 60 seconds. Table 1 lists the valid drive mix configurations you can use when you create virtual drives and allow HDD and CacheCade 2. The valid drive mix configurations are based on manufacturer settings. NOTE: Only one of the valid configurations listed in Table 1 is allowed based on your controller card manufacturing settings.
For hot spare information, see Section 2. Devices connected to enclosures have multiple paths to them. With redundant paths to the same port of a device, if one path fails, another path can be used to communicate between the controller and the device. Using multiple paths with load balancing, instead of a single path, can increase reliability through redundancy.
Applications show the enclosures and the drives connected to the enclosures. The firmware dynamically recognizes new enclosures added to a configuration along with their contents new drives.
In addition, the firmware dynamically adds the enclosure and its contents to the management entity currently in use. MegaRAID products give you the flexibility to combine these two similar technologies on the same controller, within the same enclosure, and in the same virtual drive.
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