存储数据保护Raid技术DDP说明

“With Dynamic Disk Pools, you can add or lose disk drives without impact, reconfiguration, or headaches.”
Flexible: Add ANY* number of drives for additional capacity— system automatically rebalances data for optimal performance.
* After the minimum of 11.
Combining effort: All drives in the pool sustain the workload— perfect for virtual mixed workloads or fast reconstruction if needed.
2TB Drive
3TB Drive
Typical rebalancing improvements are based on a 24-disk mixed workload
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RAID Level Comparison
RAID-0
RAID-1 and 1+0
RAID-5
RAID-6
Description
IOPS
IOPS | MB/s
IOPS | MB/s
Advantages
Performance due to parallel operation
of the access
Performance as multiple requests can be fulfilled simultaneously. Also offers the highest data availability
▪ Some sites have thousands of large-capacity drives ▪ Drive failures are continual, particularly with NL-SAS drives
Production I/O is impacted during rebuilds
Data is reconstructed onto hot spare
▪ Single drive responsible for all writes (bottleneck) ▪ Reconstruction happens linearly (one stripe at a time)
All volumes in that group are significantly impacted
SSDs operated independently with user data
and redundant information (dual parity) are striped across the SSDs. The
equivalent capacity of two SSDs is used for redundant
Disadvantages
No redundancy. One drive fails, data is lost
Storage costs are doubled
Writes are particularly demanding
Writes are particularly demanding
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Data Data Data Data
RAID 1 (10) – mirrored and striped
Data Data
Mirror Mirror
RAID 5 – data disks and rotating parity
Data Data
Data Data
Data Parity Parity Data
▪ Dynamic rebalance completes up to 8x faster than traditional RAID in random environments and up to 2x faster in sequential environments
Large pool of spindles for every volume reduces hot spots
Hot spares sit idle until a drive fails
▪ Spare capacity is “stranded”
24-drive system with 2 10-drive groups (8+2) and 4 hot spares
4
Traditional RAID—Drive Failure
Host LUNs Volumes Disk Pool SSDs
Dynamic disk pools
– Min 11 SSDs – Max 120 SSDs – Up to 10 disk pools
per system
2
SANtricity RAID Levels
RAID 0 – striped
24-drive system with 2 10-drive groups (8+2) and 4 hot spares
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The Problem
The Large-Disk-Drive Challenge
Staggering amounts of data to store, protect, access
3
Traditional RAID Volumes
Disk drives organized into RAID groups Volumes reside across the drives in a RAID group
▪ Performance is dictated by the number of spindles
▪ Larger drives equal longer rebuilds—anywhere from 10+ hours to several days
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Dynamic Disk Pools
Maintain SLAs during drive failure
Stay in the green
▪ Performance drop is minimized following drive failure
Dynamic Disk Pools Overview
DDP dynamically distributes data, spare capacity, and parity information across a pool of SSDs
– All drives are active (no idle hot spares) – Spare capacity is available to all volumes
Good for reads, small IOPS, many concurrent IOPS and random I/Os. Parity utilizes small portion of raw capacity.
Good for reads, small IOPS, many concurrent IOPS and random I/Os. Parity utilizes small portion of raw capacity.
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Data Rebalancing in Minutes vs. Days
Maintain business
SLAs with a drive1f2ai0lure
Performance Impact of a Disk Failure
Optimal Acceptable
100 80 60
Performance
Data is dynamically recreated/redistributed whenever pools grows or shrinks
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DDP: Simplicity, Performance, Protection
Simplified administration
– No RAID sets or hot spares to manage – Data is automatically balanced within pool – Flexible disk pool sizing optimizes capacity utilization
Business Impact
RAID
Time
DDP
40
DDP RAID 6
Business Impact
99% Exposure Improvement
1.3 Days
2.5 Days More than 4 Days
20
0 Hours
96 Minutes
300GB Dr(ivEestima9te00dG) B Drive
▪ Each volume spread across all drives in pool
Dynamic distribution/redistribution is a nondisruptive background operation
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mirrored SSD pairs
SSDs operated independently with user data
and redundant information (parity) are striped across the SSDs. The equivalent capacity of one SSD is used for redundant information.