How long does it take to expand a storage pool in QuTS hero?
Last modified date:
2024-08-08
Applicable Products
- QuTS hero
- Storage & Snapshots
Overview
The precise duration for expanding a storage pool in QuTS hero depends on a complex multitude of factors. However, we can use three items of information and the following equation to calculate an approximate estimate:
- The size of existing data in the storage pool (MB in binary)
- The read speed of the old RAID group (MB/s)
- The write speed of the new RAID group (MB/s)
| Estimated duration of pool expansion (in seconds) = (A / B) + (A / C) |
Important
The time calculated from this equation serves only as an approximate reference. The actual duration may vary considerably depending on many factors such as the following:
- The amount of free space in the storage pool
- The RAID group's RAID type
- The type and speed of the disks
- Current level of data fragmentation
- Available system resources (especially RAM)
- The number of other services running concurrently
Note
The storage pool expansion process is an internal I/O operation. Expanding a storage pool may affect other internal I/O operations or resync operations, just as other system operations may affect the duration of pool expansion.
Calculation Example
Let's use the above equation to calculate the approximate duration of expanding a storage pool consisting of a RAID 5 group with six 1 TB HDDs. In this example, we are adding a 1 TB HDD to the RAID group without changing the RAID type. There is 3 TB of data stored in the storage pool.
| Variable | Variable Definition | Details | Variable Value |
|---|---|---|---|
| A | The size of existing data in the storage pool (MB) | 3 TB is equivalent to 3,145,728 MB (in binary). | 3,145,728 MB |
| B | The read speed of the old RAID group (MB/s) |
| 600 MB/s |
| C | The write speed of the new RAID group (MB/s) |
| 600 MB/s |
| Estimated duration of pool expansion = (A / B) + (A / C) = (3,145,728 MB / 600 MB/s) + (3,145,728 MB / 600 MB/s) = 10,486 seconds (2 hours 55 minutes) |
Laboratory Tested Examples
In the following table, you can examine some laboratory tested examples and compare their actual durations of pool expansion against their estimated durations of pool expansion.
| Details | Example 1 | Example 2 | Example 3 | |
|---|---|---|---|---|
| Expansion method | Expanding a RAID 5 group by adding an HDD | Expanding a RAID 5 group by adding an SSD | Expanding a RAID 5 group to RAID 6 by adding two HDDs | |
| System and hardware | NAS model | TS-h3087XU-RP | TS-h3087XU-RP | TS-h3087XU-RP |
| Firmware | QuTS hero h5.1.0.2409 build 20230525 | QuTS hero h5.1.52617 build 20231219 | QuTS hero h5.1.52617 build 20231219 | |
| Memory | 64 GB | 64 GB | 64 GB | |
| Disk model | WD Ultrastar DC HC330 10TB (WUS721010ALE6L4) | Samsung SSD 870 EVO 1TB | Seagate ST1000NM0008-2F2100 1TB | |
| Storage pool before expansion | RAID group type | RAID 5 | RAID 5 | RAID 5 |
| Total disks | 3 x 10 TB HDDs | 3 x 1 TB SSDs | 3 x 1 TB HDDs | |
| Pool capacity | 17.93 TB | 1.70 TB | 1.70 TB | |
| Data (A) | 12.55 TB (13159629 MB in binary) | 1.36 TB (1426063 MB in binary) | 1.36 TB (1426063 MB in binary) | |
| Read speed (B) | 461 MB/s | 1684 MB/s | 359 MB/s | |
| Write speed | 314 MB/s | 913 MB/s | 194 MB/s | |
| Storage pool after expansion | RAID group type | RAID 5 | RAID 5 | RAID 6 |
| Total disks | 4 x 10 TB HDDs | 4 x 1 TB SSDs | 5 x 1 TB HDDs | |
| Pool capacity | 26.90 TB | 2.52 TB | 2.5 TB | |
| Read speed | 600 MB/s | 1668 MB/s | 486 MB/s | |
| Write speed (C) | 560 MB/s | 1426 MB/s | 401 MB/s | |
| Estimated duration of pool expansion (A / B) + (A / C) | (13159629 / 461) + (13159629 / 560) = 52045 seconds = 14 hours 27 minutes | (1426063 / 1684) + (1426063 / 1426) = 1847 seconds = 31 minutes | (1426063 / 359) + (1426063 / 401) = 7529 seconds = 2 hours 5 minutes | |
| Actual duration of pool expansion | 18 hours 55 minutes | 47 minutes | 2 hours 29 minutes | |
Important
- The above data is provided for reference only.
- Performance in laboratory testing conditions may be lower than in typical operational conditions.
- Actual storage pool expansion duration can vary considerably due to a multitude of factors including, but not limited to, network environment, hardware configuration, and other system usage conditions.
