Administrator Guide

4. The missing drive is placed back in its slot or the missing drive is detected and shows up. The status of the drive is
LEFTOVER.
5. Metadata of the LEFTOVER drive is cleared and the drive joins the disk group.
NOTE: If more than one drive in the disk group has a status of LEFTOVER, please contact technical support before
proceeding with any action.
6. A copyback operation from the spare drive to the drive that joined the disk group begins. The status of the disk group is
CPYBK.
7. When the copyback operation completes, the original spare drive exits the disk group and it becomes a spare drive again.
About quick rebuild
Quick rebuild is a method for reconstructing a virtual disk group that is no longer fault-tolerant after a disk failure. This method
takes advantage of virtual storage knowledge of where user data is written to rebuild only the data stripes that contain user
data.
Typically, storage is only partially allocated to volumes so the quick-rebuild process completes significantly faster than a
standard RAID rebuild. Data stripes that have not been allocated to user data are scrubbed in the background, using a
lightweight process that allows future data allocations to be more efficient.
After a quick rebuild, scrub starts on the disk group within a few minutes.
About performance statistics
You can view current or historical performance statistics for components of the storage system.
Current performance statistics for disks, disk groups, pools, tiers, host ports, controllers, and volumes are displayed in tabular
format. Current statistics show the current performance and are sampled immediately upon request.
Historical performance statistics for disks, pools, and tiers are displayed in graphs for ease of analysis. Historical statistics focus
on disk workload. You can view historical statistics to determine whether I/O is balanced across pools and to identify disks that
are experiencing errors or are performing poorly.
The system samples historical statistics for disks every quarter hour and retains these samples for 6 months. It samples
statistics for pools and tiers every 5 minutes and retains this data for one week but does not persist it across failover or power
cycling. By default, the graphs show the latest 100 data samples, but you can specify either a time range of samples to display
or a count of samples to display. The graphs can show a maximum of 100 samples.
If you specify a time range of samples to display, the system determines whether the number of samples in the time range
exceeds the number of samples that can be displayed (100), requiring aggregation. To determine this, the system divides the
number of samples in the specified time range by 100, giving a quotient and a remainder. If the quotient is 1, the 100 newest
samples will be displayed. If the quotient exceeds 1, each quotient number of newest samples will be aggregated into one sample
for display. The remainder is the number of oldest samples that will be excluded from display.
● Example 1: A 1-hour range includes 4 samples. 4 is less than 100 so all 4 samples are displayed.
● Example 2: A 30-hour range includes 120 samples. 120 divided by 100 gives a quotient of 1 and a remainder of 20. Therefore,
the newest 100 samples will be displayed and the oldest 20 samples will be excluded.
● Example 3: A 60-hour range includes 240 samples. 240 divided by 100 gives a quotient of 2 and a remainder of 40.
Therefore, each two newest samples will be aggregated into one sample for display and the oldest 40 samples will be
excluded.
If aggregation is required, the system calculates values for the aggregated samples. For a count statistic (total data transferred,
data read, data written, total I/Os, number of reads, number of writes), the samples' values are added to produce the value of
the aggregated sample. For a rate statistic - total data throughput, read throughput, write throughput, total IOPS, read IOPS,
write IOPS - the samples' values are added and then are divided by their combined interval. The base unit for data throughput is
bytes per second.
● Example 1: Two samples' number-of-reads values must be aggregated into one sample. If the value for sample 1 is 1060 and
the value for sample 2 is 2000 then the value of the aggregated sample is 3060.
● Example 2: Continuing from example 1, each sample's interval is 900 seconds so their combined interval is 1800 seconds.
Their aggregate read-IOPs value is their aggregate number of reads (3060) divided by their combined interval (1800
seconds), which is 1.7.
You can export historical performance statistics in CSV format to a file on the network for import into a spreadsheet or other
application. You can also reset current or historical statistics, which clears the retained data and continues to gather new
samples.
Getting started
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