- Notes, cautions, and warnings
- Introduction
- About your MD Series storage array
- Physical disks, virtual disks, and disk groups
- Disk pools
- Thin virtual disks
- RAID levels
- Segment size
- Virtual disk operations
- Disk group operations
- RAID background operations priority
- Virtual disk migration and disk roaming
- Advanced features
- Multi-path software
- Load balancing
- Monitoring system performance
- Interpreting performance monitor data
- Viewing real-time graphical performance monitor data
- Customizing the performance monitor dashboard
- Specifying performance metrics
- Viewing real-time textual performance monitor
- Saving real-time textual performance data
- Starting and stopping background performance monitor
- Viewing information about the current background performance monitor session
- Viewing current background performance monitor data
- Saving the current background performance monitor data
- Viewing saved background performance monitor data
- Invalid objects in Performance Monitor
- Discovering and managing your storage array
- Out-of-band management
- In-band management
- Storage arrays
- Setting up your storage array
- Locating storage arrays
- Naming or renaming storage arrays
- Setting a password
- Adding or editing a comment to an existing storage array
- Removing storage arrays
- Enabling premium features
- Displaying failover alert
- Changing the cache settings on the storage array
- Changing expansion enclosure ID numbers
- Changing the enclosure order
- Configuring alert notifications
- Battery settings
- Setting the storage array RAID controller module clocks
- Using iSCSI
- Changing the iSCSI target authentication
- Entering mutual authentication permissions
- Creating CHAP secrets
- Changing the iSCSI target identification
- Changing iSCSI target discovery settings
- Configuring the iSCSI host ports
- Advanced iSCSI host port settings
- Viewing or ending an iSCSI session
- Viewing iSCSI statistics and setting baseline statistics
- Edit, remove, or rename host topology
- Event monitor
- About your host
- Disk groups, standard virtual disks, and thin virtual disks
- Creating disk groups and virtual disks
- Thin virtual disks
- Advantages of thin virtual disks
- Physical vs virtual capacity an a thin virtual disk
- Thin virtual disk requirements and limitations
- Thin virtual disk attributes
- Thin virtual disk states
- Comparison—Types of virtual disks and copy services
- Rollback on thin virtual disks
- Initializing a thin virtual disk
- Changing a thin virtual disk to a standard virtual disk
- Utilizing unmapping for thin virtual disk
- Enabling unmap thin provisioning for thin virtual disk
- Choosing an appropriate physical disk type
- Physical disk security with self encrypting disk
- Configuring hot spare physical disks
- Physical disk security
- Enclosure loss protection
- Drawer loss protection
- Host-to-virtual disk mapping
- Creating host-to-virtual disk mappings
- Modifying and removing host-to-virtual disk mapping
- Changing RAID controller ownership of the virtual disk
- Removing host-to-virtual disk mapping
- Changing the RAID controller module ownership of a disk group
- Changing the RAID level of a disk group
- Removing a host-to-virtual disk mapping using Linux DMMP
- Restricted mappings
- Storage partitioning
- Disk group and virtual disk expansion
- Disk group migration
- Storage array media scan
- Disk pools and disk pool virtual disks
- Difference between disk groups and disk pools
- Disk pool restrictions
- Creating a disk pool manually
- Automatically managing unconfigured capacity in disk pools
- Locating physical disks in a disk pool
- Renaming a disk pool
- Configuring alert notifications for a disk pool
- Adding unassigned physical disks to a disk pool
- Configuring the preservation capacity of a disk pool
- Changing the modification priority of a disk pool
- Changing the RAID controller module ownership of a disk pool
- Checking data consistency
- Deleting disk pool
- Viewing storage array logical components and associated physical components
- Secure disk pools
- Changing capacity on existing thin virtual disks
- Creating thin virtual disk from disk pool
- Using SSD cache
- How SSD cache works
- Benefits of SSD cache
- Choosing SSD cache parameters
- SSD cache restrictions
- Creating an SSD cache
- Viewing physical components associated with an SSD cache
- Locating physical disks in an SSD cache
- Adding physical disks to an SSD cache
- Removing physical disks from an SSD cache
- Suspending or resuming SSD caching
- Changing I/O type in an SSD cache
- Renaming an SSD cache
- Deleting SSD cache
- Using the performance modeling tool
- Premium feature—Snapshot Virtual Disk
- Snapshot images and groups
- Snapshot Virtual Disk read/write properties
- Snapshot groups and consistency groups
- Understanding snapshot repositories
- Creating snapshot images
- Scheduling snapshot images
- Performing snapshot rollbacks
- Creating snapshot group
- Converting a snapshot Virtual Disk to read-write
- Viewing associated physical components of an individual repository virtual disk
- Creating consistency group
- Creating a snapshot virtual disk of a snapshot image
- Snapshot Virtual Disk limitations
- Creating Snapshot Virtual Disk
- Creating a Snapshot Virtual Disk repository
- Changing the settings of a Snapshot Virtual Disk
- Disabling Snapshot Virtual Disk or consistency group Snapshot Virtual Disk
- Re-creating a Snapshot Virtual Disk or consistency group Snapshot Virtual Disk
- Renaming a Snapshot Virtual Disk or consistency group Snapshot Virtual Disk
- Creating consistency group Snapshot Virtual Disk
- Manually creating a consistency group Snapshot Virtual Disk repository
- Disabling Snapshot Virtual Disk or consistency group Snapshot Virtual Disk
- Re-creating a Snapshot Virtual Disk or consistency group Snapshot Virtual Disk
- Changing the modification priority of an overall repository virtual disk
- Changing the media scan setting of an overall repository virtual disk
- Changing the pre-read consistency check setting of an overall repository virtual disk
- Increasing capacity of overall repository
- Decreasing the capacity of the overall repository
- Performing revive operation
- Premium feature—virtual disk copy
- Types of virtual disk copies
- Creating a virtual disk copy for an MSCS shared disk
- Virtual disk read/write permissions
- Virtual disk copy restrictions
- Creating a virtual disk copy
- Preferred RAID controller module ownership
- Failed RAID controller module
- Copy manager
- Copying the virtual disk
- Storage array performance during virtual disk copy
- Setting copy priority
- Stopping a virtual disk copy
- Recopying a virtual disk
- Removing copy pairs
- Device Mapper multipath for Linux
- Configuring Asymmetric Logical Unit Access
- Premium feature—Remote Replication
- About asynchronous Remote Replication
- Remote replicated pairs and replication repositories
- Types of Remote Replication
- Remote Replication requirements and restrictions
- Setting up Remote Replication
- Activating Remote Replication premium features
- Deactivating Remote Replication
- Remote Replication groups
- Replicated pairs
- Management firmware downloads
- Downloading RAID controller and NVSRAM packages
- Downloading both RAID controller and NVSRAM firmware
- Downloading only NVSRAM firmware
- Downloading physical disk firmware
- Downloading MD3060e Series expansion module EMM firmware
- Self-Monitoring Analysis and Reporting Technology (SMART)
- Media errors and unreadable sectors
- Firmware inventory
- System interfaces
- Storage array software
- Start-up routine
- Device health conditions
- Trace buffers
- Collecting physical disk data
- Event log
- Recovery Guru
- Storage array profile
- Viewing the physical associations
- Recovering from unresponsive storage array condition
- Locating a physical disk
- Locating an expansion enclosure
- Capturing state information
- SMrepassist utility
- Unidentified devices
- Recovering from unidentified storage array
- Starting or restarting the Host Context Agent software
- Getting help
Dell EMC PowerVault MD 34XX/38XX Series Storage Arrays Administrator's Guide
Segment size migration
Segment size
refers to the amount of data (in kilobytes) that the storage array
writes on a physical disk in a virtual disk before writing data on
the next physical disk. Valid values for the segment size are 8 KB,
16 KB, 32 KB, 64 KB, 128 KB, and 256 KB.
Dynamic segment size migration enables the segment size of a given virtual disk to be changed. A default segment size is set when the virtual disk is created, based on such factors as the RAID level and expected usage. You can change the default value if segment size usage does not match your needs.
When considering a segment size change, two scenarios illustrate
different approaches to the limitations:
- If I/O activity stretches beyond the segment size, you can increase it to reduce the number of disks required for a single I/O. Using a single physical disk for a single request frees disks to service other requests, especially when you have multiple users accessing a database or storage environment.
- If you use the virtual disk in a single-user, large I/O environment (such as for multimedia application storage), performance can be optimized when a single I/O request is serviced with a single data stripe (the segment size multiplied by the number of physical disks in the disk group used for data storage). In this case, multiple disks are used for the same request, but each disk is only accessed once.
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