CAPÍTULO 2: FASE DE FORMACIÓN
2.2. Formación brindada por la IED O.E.A
Whether you protected a disk using the Protect Multiple Disks interface or the Protect Disk Wizard, you can review and modify protection policy details in the Properties dialog for an individual disk or group. You can modify a variety of options for mirror mode, synchronization and snapshot schedules, and performance.
To display the Properties dialog, expand DiskSafe --> Protected Storage in the DiskSafe console.
For a disk that is not part of a group, select Disks.
In the right pane, double-click the disk or right-click a disk below the Disks object or in the right pane and select Properties.
For a group, expand Groups.
Right-click a group name below the Groups object or in the right pane with Groups selected and select Properties.
For a disk that is part of a group, expand a group name and select the disk in the
right pane.
Notes:
If you are returning to the DiskSafe console after working in the Protect Multiple
Disks window, click Refresh to refresh information about protected disks.
It is not possible to modify protection properties if a restore operation is in
General tab
For a protected device:
The General tab includes information about the protection policy.
Information includes:
Name of the device
Capacity - size of the device
Mirror - name used to identify the mirror
Mode - mirror synchronization mode (Continuous or Periodic)
For a mirror in Periodic mode, the data difference between the primary and mirror disks before the most recent synchronization
Current activity - What is happening on the mirror right now?
Activity duration - How long has the current activity been going on? Status - normal or not normal
Maximum I/O allowed - amount as set for the device Encryption - Whether or not data on the mirror is encrypted
Last synchronization - date/time of the most recent synchronization
Last result - result of the most recent synchronization
Number of snapshots - number of existing snapshots (not displayed for a device in a group)
Last snapshot - date/time of the most recent snapshot (not displayed for a device in a group)
For a protected group:
Similar information is displayed in the General tab for a group:
Group name
Group synchronization mode (the group itself does not have a mirror)
Current activity Total members
Last synchronization Last result
Number of snapshots Date/time of last snapshot.
Mode tab
For a protected device, the Mode tab displays information about the mirror. For a group, the Mode tab displays information about the group’s synchronization mode and synchronization/snapshot schedule.
Mirror mode and schedule
To change the current mirror synchronization mode for the selected device or group, select the appropriate radio button. If you change the synchronization mode, define a synchronization or snapshot schedule.
Periodic mode updates the mirror at regularly scheduled intervals. For a
Periodic mode policy, the current synchronization schedule is displayed. Click Change to create/review/change the schedule.
Continuous mode saves every write to the protected disk to the mirror. For a Continuous mode policy, the current schedule for taking automatic snapshots of the mirror device is displayed.
Note: For a weekly or monthly schedule, the selected day of the week is represented by a number as follows: 1=Monday, 2=Tuesday... 7=Sunday.
Click Schedule to create/review/change the schedule.
Schedule
Synchronization and snapshot schedules include similar dialogs.
The Schedule Details dialog is displayed for a mirror set to Periodic mode in order to create the required synchronization schedule.
Notes:
Snapshots will not be taken if you do not set a snapshot schedule; however,
but you can still take manual snapshots (refer to ’Take a manual snapshot’).
If you chose a local mirror for the selected disk, this option will not be available because snapshots are not supported.
Snapshot agents can be invoked for only one protection policy for a single resource or for a group at a time. In order to avoid possible snapshot failure, make sure snapshot schedules do not overlap.
If any other DiskSafe operation (such as synchronization, disk analysis, or
restore) is in progress at the time a snapshot is scheduled, the snapshot will be taken when the operation has finished.
However, if Suspend active disk analysis... is selected for Global Disk Analysis, disk analysis will be suspended during a scheduled synchronization or snapshot operation (refer to ‘Global disk analysis options’).
In the Task Creation dialog that is displayed when you click Schedule, you
The synchronization and snapshot schedules include similar dialogs for Periodic and Continuous synchronization modes.
The Task Creation dialog is displayed for a mirror set to Continuous mode in order to create a snapshot task that will occur based on the specified schedule. The task name is created by default and cannot be modified.
Specify a start date and time. Click the button to the right of the date/time fields to display a calendar.
Specify schedule details; available options depend on the selected frequency. By default, the schedule is set to perform synchronization/take a snapshot once a day at the current time, starting on the current date.
Click Hourly to run the task every x hours and y minutes. Enter the number of hours (0-24) and minutes (between 0 and 60).
Click Daily to run the task every specified number of days.
Click Weekly to run the task every specified number of weeks and then specify the
day of the week the synchronization is to occur.
Click Monthly to run the task every specified number of months and specify the day of the month or the first, second, third, fourth or last instance of a specified day of the week.
Each schedule allows you to specify months, days, dates, or times - plus holidays - that you want to exclude from the synchronization or snapshot schedule. To view and select Advanced Schedule Options, click Advanced in the Schedule Details or
Note: If synchronization takes longer than the specified interval, the next
synchronization begins at the next scheduled time. For example, if you schedule synchronization to occur every 30 minutes beginning at 9:00 A.M., and
synchronization takes 45 minutes, the next scheduled synchronization will occur at 10:00 A.M., since the 9:30 A.M. synchronization time will have already elapsed.
For a daily schedule, you can specify dates to exclude in all or selected months and weekdays.
For an hourly schedule, you can also exclude times, based on a 24-hour clock
(for example, 1, 15, 24),
For a weekly schedule, you can exclude dates and months. For a monthly schedule, you can exclude months and weekdays.
All schedule options allow you to define holidays to exclude from the schedule. Select Defined Holidays in the Advanced Schedule Options dialog and then select View. To add holidays to the list, click Create and enter the name of the holiday and its date and month, then click OK.
To modify this list later on, display it the same way and then create additional holidays or select an item in the list to delete or edit it via the related command buttons in the dialog.
When you are done, click OK to return to Advanced Schedule Options, then OK again to return to the Schedule Details or Task Creation dialog. Review the schedule, then click OK again to return to the Mode tab.
Snapshot frequency
When synchronization for a DiskSafe mirror is set to Periodic mode, you can change this value, which controls how often a snapshot should be taken relative to synchronizations. This option is not available for local mirrors, which do not support snapshots.
Advanced disk options
To view/modify advanced disk options related to synchronization and mirror
performance for a mirror set to Periodic or Continuous mode, click Advanced in the Mode tab for the protected disk or group. Choose the options that are appropriate for your system. (For a group, refer to ‘Advanced group options’.)
Synchronization options
Note: If synchronization is occurring when a snapshot is scheduled to occur, the snapshot will be taken after that operation has completed. However, for systems that experience non-stop I/O, synchronization may never complete entirely, and as a result, automatic snapshots will not occur. To resolve this, you can
Synchronization options affect synchronization behavior based on I/O, optimization preference, conditions that trigger this operation, and whether or not failed
synchronization should be retried. The following options are available:
Optimize data copy during synchronizations - DiskSafe scans the protected disk and its mirror in 64 KB blocks and copies any 64 KB block containing changed data to the mirror. For example, if only one KB of data changed on the disk, the entire 64 KB block that contains this change is copied to the mirror. Block size changes dynamically based upon available memory. The size of the protected disk, the physical location of the changed data on the disk, the speed of the processor, and the bandwidth of the network all affect how quickly the disk can be scanned for changes and how quickly the changes can be copied to the mirror. This option provides some control over this process.
Consider the following factors when deciding whether this option is appropriate for your environment:
This option minimizes the amount of data copied to the mirror. If you select
this option, DiskSafe scans the protected disk and its mirror in 4 KB blocks and copies any 4 KB block containing changed data to the mirror. For example, if only one KB of data changed on the disk, only a 4 KB block is copied to the mirror.
In environments with slow connection speeds or low bandwidth, this can minimize impact on the network if you previously mirrored to the selected disk. However, the scan to identify changed data will require more
processing time.
In addition, the first synchronization/snapshot that occurs after a mirror disk is expanded from the DiskSafe console will require extra processing to scan added space for changes.
By comparison, default synchronization copies more data to the mirror but requires less processing time to identify changed blocks.
Limit I/O throughput generated (KB/s) - Select or clear the Limit I/O throughput generated (KB/s) check box to indicate whether or not to limit the speed at which data is written to the mirror.
Note: If the selected device is part of a group, options for synchronization retry and for performing synchronization based on the amount of new/changed data are not available; they are controlled at the group level.
Note: This option can reduce the need for event-based disk analysis during restart after ungraceful shutdown (refer to ‘Understand automatic analysis during restart following ungraceful shutdown’).
If you select this option, you must also specify the number of kilobytes per second in the adjacent text box. If the throughput generated by DiskSafe exceeds this maximum, mirroring is temporarily paused, thereby freeing the host’s processing bandwidth for other ongoing activities.
If you clear this option, data is written to the mirror as quickly as possible. This might slow the performance of other applications, since processing bandwidth will be used for this DiskSafe activity.
If synchronization fails, retry for every (specified number of minutes) - This
option is available for both Periodic and Continuous mode and is automatically selected for Continuous mode.
This option retries synchronization between the protected disk and its mirror with the specified frequency.
For Continuousmode, clear this checkbox to cancel retries.
Perform synchronization when the amount of data exceeds x MB) - This option is available only for Periodic mode and is selected by default.
Select this option to trigger synchronization when the amount of delta data exceeds the number specified. The values are as follows:
For disks equal to or greater than 1 GB, the minimum is 10 MB, the default is 1024 MB, and the maximum is equal to the primary disk capacity.
For disks greater than 512 MB and less than 1 GB, the minimum is 10 MB, the default is 512 MB, and the maximum is 1024 MB.
For disks less than 512 MB, the minimum is 10 MB, the default is 256 MB, and the maximum is 512 MB.
Number of outstanding I/Os for synchronization - This option allows you to specify concurrent I/O commands during synchronization. The value is between 1 to 128. When you are protecting a system disk or the encrypted policy, the default is 1, otherwise the default is 4.
Suspend I/O when mirror disk throughput deteriorates - This option allows you to specify whether or not to temporarily pause synchronization when the mirror is not responding quickly enough.
If you do not select this option, DiskSafe will wait until data is successfully written to the mirror before it continues to write data to the protected disk, which can adversely affect system performance
If you select this option, data will continue to be written to the protected disk even if there are delays in writing it to the mirror. This is particularly important when you set Continuous mirror mode for a system disk. If you select this
Note: If you configured registry settings for SnapshotRetryCount and SnapshotRetryInterval, do not use this option (refer to ’Modify snapshot retry settings’).
Acceptable throughput - This option allows you to select a maximum number of kilobytes per second that can be written to the mirror. If you clear this option, synchronization will not be temporarily paused when the mirror is not responding quickly enough. As a result, the host might hang while waiting for the mirror to acknowledge that data has been written to it.
Click Detect to determine the optimum throughput setting for the disk where the mirror resides. It is recommended that you do not set this value higher than the value displayed by the test to ensure DiskSafe trigger a
synchronization pause when needed.
For example, you might set the acceptable throughput to 10240 KB/s, and the deterioration threshold to 75%. If the throughput to the mirror falls to 7680 KB/s, DiskSafe will temporarily pause synchronization.
Deterioration threshold to suspend I/O - This option allows you to select the percentage of the acceptable throughput at which synchronization will pause.
Performance options
Performance options allow you to favor synchronization between the protected resource and its mirror over performance as a whole, or conversely, to favor performance over synchronization. When the number of synchronization I/Os reaches the maximum number of mirror buffers multiplied by two, mirror synchronization stops and then resumes after a specified wait time. When the maximum number of mirror buffers is set to 1024, you can have up to 2048 pending I/Os before performance is affected. The following mirror performance options are available; you can select only one.
Minimize performance impact to primary I/O - Select this option to favor
primary I/O performance, even if this might result in synchronization failure. This option sets the maximum number of mirror buffers to 64 and sets the wait time to 1 second.
Optimize data mirror coverage - Select this option to favor synchronization
even if this might impact primary I/O performance. This option sets the
maximum number of mirror buffers to 64 and sets the wait time to 10 seconds. If the mirror is a disk that you just allocated in the wizard, or if you selected a mirror that was used before as the target for a different source disk, do not select this option.
Balance performance and coverage - (Default setting for Continuous mode.)
This option balances I/O performance and mirror synchronization by setting the maximum number of mirror buffers to 64 and setting the wait time to 2 seconds.
Aggressive performance - (Default setting for Periodic mode.) This option favors synchronization by expanding both the maximum number of mirror buffers as well as the wait time, decreasing the possibility of disengaging the mirror before scheduled synchronization completes. The maximum number of
Advanced custom settings - Select this option to enable the Set button. Clicking Set displays the Advanced Settings dialog that provides control
parameters for the mirror buffer maximum and wait time. The default values are 512 mirror buffers and 10-second wait time. You can increase the number of mirror buffers up to 1024 and the maximum wait time up to 3600 seconds.
Advanced group options
For a group, click Advanced in the Mode tab to change advanced synchronization options and advanced snapshot options in the Advanced Group Options dialog.
Refer to ‘Advanced disk options’ for information about synchronization options. Refer to ‘Snapshot tab’ for information on snapshot options for temporary snapshots (Continuous mode only) and the snapshot retention policy.
When you are done, click OK to return to the Mode tab.
Storage tab
The Storage tab displays information about the primary disk and its mirror. The same information is displayed for a primary disk that belongs to a group. You cannot change this information.
This tab is not displayed for a group.
Information includes:
Primary disk name
Device ID
Location - SCSI address (local disks only), or port number, bus number, target ID, and logical unit number (remote disks only)
Storage server - name or IP address of the storage server that manages the primary disk (Local Host for a local disk)
Original name - name of the primary disk on the storage server (N/A for a local disk)
Mirror disk name
Name/number Device ID
Original name - name of the mirror disk on the storage server (N/A for a local disk)
Protocol - communications protocol used to communicate with the storage server (remote disks only)
Snapshot - Enabled/disabled - whether or not snapshots are enabled for the mirror
Max snapshots - The maximum number of snapshots supported by the storage server
Snapshot tab
The Snapshot tab displays snapshot settings for the selected device or group. You can change these options.
This tab is not displayed if the selected device belongs to a group, or for a group.
Snapshot options
Snapshot options control temporary snapshots that can be taken before synchronization in Continuous mode and whether snapshot agents should be invoked before a snapshot is taken in both Periodic and Continuous synchronization modes.
Take a temporary snapshot before each synchronization to recover the mirror in case of failure - (Continuous mode only) When this option is selected, a snapshot of the mirror is taken before the protected disk and its mirror are synchronized. This ensures that, if an error occurs during
synchronization, the mirror can be restored to its previous state. Once