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Full Discussion: Software RAID configuration
Operating Systems Linux Red Hat Software RAID configuration Post 302449357 by mark54g on Monday 30th of August 2010 10:41:17 AM
Old 08-30-2010
As well, be advised that RAID 5 without sparing is potentially dangerous, depending on the need for availability.

If you lose 1 drive, you go into a degraded state, which will severely impact performance until another drive has been rebuilt. This is an issue with both software and hardware RAID.

Also, there are lots of things to investigate when using RAID 5, such as the chunk size in relation to your usage patterns as well as other tunables (read ahead, etc).

How many drives are you using in your array?
 

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saconfig(1M)															      saconfig(1M)

NAME
saconfig - Command Line Configuration Utility for the HP SmartArray RAID Controller Family SYNOPSIS
<device_file> <device_file> -N <device_file> -R <RAID_level> [-S <stripe_size>] -p <physical_drive_id> [-p <physical_drive_id> ...] [-s <physical_drive_id>] [-c <capac- ity>] <device_file> -e <low|medium|high> <device_file> -r <low|medium|high> <device_file> -P <default|shortest|longest> <device_file> -A <logical_drive_num> -s <physical_drive_id> <device_file> -D <logical_drive_num> -s <physical_drive_id> <device_file> -D <logical_drive_num> -s all <device_file> -D <logical_drive_num> <device_file> -D all <device_file> -C <read_caching_percentage> <device_file> -F on <device_file> -F off <device_file> -I -p <physical_drive_id> [-p <physical_drive_id> ...] <device_file> -I -l <logical_drive_num> <device_file> -E <logical_drive_num> -c <capacity> <device_file> -E <logical_drive_num> -p <physical_drive_id> [-p <physical_drive_id> ...] <device_file> -M <logical_drive_num> -R <RAID_level> [-S <stripe_size>] <device_file> -M <logical_drive_num> -S <stripe_size> DESCRIPTION
The command is a command line configuration tool for the HP SmartArray RAID Controller Family. This command provides the ability to create a logical drive, add a spare drive to existing logical drive, display configuration, delete a logical drive, and clear configuration. This command also enables the cache when it is used to create the first logical drive on the SmartArray RAID Controller. Furthermore it allows the option of changing the percentage of total cache size used for read caching and write caching. The auto-fail missing disks at boot fea- ture can be enabled or disabled using this command. Prerequisites needs to be able to create the /tmp/saconfig.lock file when it starts executing. This prevents multiple users from running This lock file is removed when exits. Security Restrictions requires either the superuser privilege or and privileges. See privileges(5) for more information about privileged access on systems that support fine-grained privileges. Options recognizes the following options and parameters as indicated in the SYNOPSIS section above. <device_file> To specify the device file for the SmartArray RAID Controller. The device file is as displayed by the command for the appropriate SmartArray RAID Controller. With no other options, displays size and status for all physical drives and RAID level, size, and status for all logical drives. With the option saconfig displays size and status for all physical drives and RAID level, size, and status for all logical drives. But the persistent device files (see intro(7)) will be displayed as against legacy device files in the absence of this option. -R <RAID_level> To create a logical drive with the specified RAID level. The supported RAID levels are 0, 1, 1+0, 5, and ADG. The lowest logical drive number not already in use will be given to the newly created logical drive, starting from 0. To determine the hardware path and device file for the logical drive, use the command. The logical drives are dis- played in the same order as in the output. RAID 1+0 logical drive requires even number of physical drives (minimum of 2). To achieve optimal fault tolerance, it is best to specify the same number of physical drives per channel if possible when creating a RAID 1+0 logical drive. This ensures the physical drives in each mirrored pairs would be on different channels. -S <stripe_size> To specify the stripe size for the logical drive to be created. The supported stripe sizes are 8, 16, 32, 64, 128, and 256 (KB). 128 and 256 stripe sizes are not available for RAID 5 or ADG logical drive. If this option is not used to specify the stripe size, default stripe size will be used to create the logical drive. For RAID 0 and 1+0 logical drive, the default size is 128. For RAID 5 and ADG logical drive, the default size is 16. -p <physical_drive_id> To specify the SCSI physical disk. It can be represented as <channel_id>:<target_id> (e.g., 4:12). Valid channel numbers are between 1 and 4. Valid target numbers are between 0 and 15. To specify the SAS/SATA physical disk. It can be represented as either <connector>:<enclosure>:<bay> (e.g., 2I:1:10) or <wwid> (e.g., 0x500000e010f16432). -s <physical_drive_id> To specify a spare drive to be included in the logical drive configuration. Refer <physical_drive_id> to -p option. -c <capacity> To specify the size in GB of a logical drive to be created. -A <logical_drive_num> To specify which logical drive to add spare drive to. -e <low | medium | high> To change the expand priority of controller to one of Low, Medium, High. When there are no logical drives, expand priority cannot be changed. When the configuration is cleared, or the last logical drive is deleted, the subse- quent logical drive creation will change the expand priority value of the controller to medium. -r <low | medium | high> To change the rebuild priority of controller to one of Low, Medium, High. When there are no logical drives, rebuild priority cannot be changed. When the configuration is cleared, or the last logical drive is deleted, the subsequent logical drive creation will change the rebuild priority value of the controller to high. -P <default | shortest | longest> To change the path selection method by the controller firmware. If it is set to default, firmware will select the Active path on its own. If the selection method is set to shortest, firmware will select the shortest path as the Active Path. If the path selection method is longest, firmware will select the longest path as the Active Path. All multi path configurations are Active-Standby configurations. -D <logical_drive_num> -s <physical_drive_id> To delete the spare drive from the specified logical drive. -D <logical_drive_num> -s all To delete all of spare drives from the specified logical drive. -D <logical_drive_num> To delete the specified logical drive. -D all To clear configuration. -C <read_caching_percentage> To specify the percentage of total cache size to be used for read caching. The remaining percentage will be used for write caching. Valid read caching percentage numbers are 0, 25, 50, 75, and 100 (%). -F on To enable auto-fail missing disks at boot feature. -F off To disable auto-fail missing disks at boot feature. -I -p <physical_drive_id> [-p <physical_drive_id> ...] To identify SAS/SATA physical drive(s) by LED. -I -l <logical_drive_num> To identify a SAS/SATA logical drive by LED. -E <logical_drive_num> -c <capacity> To extend the capacity of the specified logical drive up to larger capacity. The capacity is in GB. -E <logical_drive_num> -p <physical_drive_id> [-p <physical_drive_id> ...] To expand the specified logical drive and others in an array by physical drive(s). -M <logical_drive_num> -R <RAID_level> [-S <stripe_size>] To perform RAID level [with stripe size] migration on the specified logical drive. The stripe size is in KB. -M <logical_drive_num> -S <stripe_size> To perform stripe size migration on the specified logical drive. The stripe size is in KB. Logical Drive State Definitions All physical disks in the logical drive are operational. Some possible causes: Multiple physical disks in a fault-tolerant (RAID 1, 1+0, 5, ADG) logical drive have failed. One or more disks in a RAID 0 logical drive have failed. Cache data loss has occurred. Array expansion was aborted. The logical drive is temporarily disabled because another logical drive on the controller had a missing disk at power-up. Also known as "degraded" state. A physical disk in a fault tolerant logical drive has failed. For RAID 1, 1+0 or 5, data loss may result if a second disk should fail. For RAID ADG, data loss may result if two additional disks should fail. A replacement disk is present, but rebuild hasn't started yet (another logical drive may be currently rebuilding). The logical drive will also return to this state if the rebuild had been aborted due to unrecoverable read errors from another disk. One or more physical disks in this logical drive are being rebuilt. While the logical drive was in a degraded state, the system was powered off and a disk other than the failed disk was replaced. Shut off the system and replace the correct (failed) disk. While the system was off, one or more disks were removed. Note: the other logical drives are held in a temporary "failed" state when this occurs. The data in the logical drive is being reorganized because: Physical disks have been added to the array (capacity expansion). The stripe size is being changed (stripe-size migration). The RAID level is being changed (RAID-level migration). A capacity expansion operation is in progress (or is queued up) that will make room on the disks for this new logical drive. Until room has been made on the physical disks, this newly configured logical drive cannot be read or written. The logical drive is waiting to undergo data reorganization (see EXPANDING above). Possible causes for the delay are a rebuild or expansion operation may already be in progress. Physical Disk State Definitions The physical disk is configured in one or more logical drives and is operational. The physical disk is configured as a spare disk. The physical disk has not been configured in any logical drives. The configured physical disk has failed. Return Value returns the following values: Successful completion. Command line syntax error. Incompatible CISS driver API. Failure opening a file. Other error. Examples To display configuration on the SmartArray RAID Controller /dev/ciss5 - To create a RAID 1+0 logical drive to include physical drives 4:0 and 4:1 and spare drive 4:2 - -R -p -p -s To create a RAID ADG logical drive with stripe size 64 to include physical drives 1:2, 2:2, 3:2 and 4:2 - -R -S -p -p -p -p To create a RAID 5 logical drive with capacity 45 GB to include SAS physical drives 1I:1:16, 1I:1:15, and 1I:1:14 - -R -c -p -p -p To set the expand priority of logical drives on a controller to medium -e To set the rebuild priority of logical drives on a controller to high -r To add spare drive 1:0 to logical drive 1 - -A -s To delete spare drive 1:0 from logical drive 1 - -D -s To delete all spare drives from logical drive 1 - -D -s To delete logical drive 0 - -D To clear configuration - -D To change read caching percentage to 75% - -C To extend logical drive 2 upto 45 GB in capacity - -E -c To expand logical drive 0 with 2 SAS physical drives - -E -p -p To migrate logical drive 2 with stripe 32 - -M -S To migrate logical drive 2 to RAID level 5 with stripe 64 - -M -R -S AUTHOR
was developed by HP. FILES
Executable file. saconfig lock file. Device files. SEE ALSO
sautil(1M), privileges(5), intro(7). saconfig(1M)
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