SIRIS 3 vs SIRIS 4 Enterprise Comparison


This article compares hardware and virtualization performance of SIRIS 3 and SIRIS 4 Enterprise devices.


  • Datto SIRIS 3 Enterprise
  • Datto SIRIS 4 Enterprise


Hardware comparison

SIRIS 3 Enterprise SIRIS 4 Enterprise Improvements in SIRIS 4
CPU Intel Broadwell Intel Cascade Lake

Greater CPU core count

40% higher CPU performance


4x channel

Up to 32 GB per DIMM

Up to 512 GB DIMM

6x channel

Up to 64 GB per DIMM

Up to 1 TB DIMM

More channels

More memory bandwidth

More capacity

ZFS SLOG None Intel Optane NVMe

10x faster VM boot

Improved VM IOPS

NIC 2x 10 Gbe 2x 10 Gbe + 2x 1 Gbe 2x additional 1 Gbe NIC
Hard Drive Up to 6 TB HDD Up to 12 TB HDD

Larger capacity drive

Saves rack space

Backplane Active backplane Passive backplane Improved reliability
Chassis 2U and 4U 2U only

Denser system

Saves rack space

Virtualization boot time test

This test compares how fast you can recover in the event of a disaster.

Test setup

  • 10 Agents (Windows 7 server pack, new install, all identical).
  • SIRIS 3 Enterprise (S3E): S3E36, dual Intel 2650 v4, 9x 6TB HDD, 128GB memory
  • SIRIS 4 Enterprise (S4E): S4E36, dual Intel 4216, 9x 6TB HDD, 128GB memory
  • Virtual machines for the agents were spun up one by one, and boot time was measured.

Test results

  • S4E bootup time is much faster: 4 VMs take 5 minutes, ~9x faster than S3E (44 minutes).
  • S3E takes longer to boot, especially when more VMs are running.
  • S4E curve is linear and maintains consistent bootup time, which means that it can handle more VMs at the same time.
VM boot up time in minutes (cumulative)
Number of VMs SIRIS 3 Enterprise SIRIS 4 Enterprise
1 3 0.7
2 13 2
3 28 3
4 44 5
5 62 6
6 80 8
7 98 10
8 116 12

Figure 1: SIRIS VM bootup time

IOPS virtualization performance test

This test measures input and output per second (IOPS) within a virtual machine running on the Datto device.

Test setup

  • 1 Agent (Windows 2012 R2, new install, with diskspd installed).
  • Siris 3 Enterprise (S3E): S3E36, dual Intel 2650 v4, 9x 6TB HDD, 128GB memory installed.
  • Siris 4 Enterprise (S4E): S4E36, dual Intel 4216, 9x 6TB HDD, 128GB memory installed.
  • Test tool: diskspd. Storage performance tool written by Microsoft. Refer to (external link) for details.
  • Engineers ran diskspd in a Windows VM and measured the performance.

Test results

  • Test 1-2 (100% write test): S4E gains 2000%-7000% improvement over S3E because SLOG offloads synchronous write away from the pool, and frees up resources for real application.
  • Test 3-4 (100% read test): S4E shows 20-30% improvement over S3E. This result is reasonable as slog is a write buffer, doesn’t help reading speed directly.
  • Test 5 (70% read and 30% write): S4E is 71x times faster. Slog improves overall system performance when the system has a mixed workload.
IOPS (diskspd) Test results
Test S3E IOPS S4E IOPS Percent improvement
1 Random write
(storage/incremental backup)
206 14850 7097%
2 Sequential write
(storage/backup/video surveillance)
660 17525 2554%
3 Random read
(Desktop/web server)
22361 29597 32%
4 Sequential read
(Video streaming/application server)
26337 31803 21%
5 Random 70% read, 30% write
(Database query/file server/email)
243 17505 7104%


  • S4E is 9x faster at VM boot up because ZFS SLOG offloads a high-latency synchronous write from the pool drive and reduces data IO latency, thereby reducing the time to boot a VM.
  • S4E has 25-70x better IOPS within the VM for write-related workload, thereby improving VM performance for a variety of real-time workloads.

Additional Resources