Configuration environments
bsr has no restrictions on the target environment such as physical system and virtual machine (VM), hyperconverged infrastructure (HCI) environment, and can flexibly configure replication in any network environment such as a local network and a remote network environment between WANs.
Specifications
The following are the physical requirements of the platforms and target systems supported by the BSR.
Platforms
Supports Windows 2012 or higher, Linux CentOS 6.4, Ubuntu 16.04 LTS or higher x64 environment.
File systems
Block replication solutions usually work regardless of the type of file system. However, bsr has a specification for supported file systems, as it implements fast synchronization that only synchronizes to the areas used by the file system.
Recently, the capacity of the replication volume has been increasing in capacity (several tens to hundreds of terabytes), and accordingly, the time required to initially synchronize the replication volume is increasing significantly. In many cases, it may take days to dozens of days. This is because the volume is initially synchronized because it targets the entire disk volume. If the volume is 10 terabytes in 1 Gbps network bandwidth, it will take at least 27 hours at least as fast as possible to complete the entire synchronization, and over 10 days if 100 TB.
We have implemented Fast Sync (FastSync) to solve this excessive sync time issue. FastSync is a function that synchronizes only the area used in the file system of the replication volume, dramatically improving the initial synchronization time. For example, if you are using only 10 GB of actual volume at 100 TB capacity, FastSync will complete synchronization within 1 minute in the 1 Gbps band. However, since it is a function developed using the characteristics of a file system, it depends on the file system type and has a support specification for the file system type accordingly.
bsr supports NTFS and ReFS file systems commonly used in Windows, and Ext-like file systems (ext3 or higher) and xfs file systems in Linux. These file systems are the types of file systems most commonly used by general users, and we plan to gradually support other file systems.
Even so, it is not possible to configure replication for file systems that are not supported by bsr's FastSync. You can't just use FastSync, and it works with the existing full sync method, so there is no compatibility problem.
CPU
It is recommended to configure at least 2GHz, 4 core or higher, x64 compatible processor. There is no problem in operating in a processor environment with a lower specification, but considering the I / O performance of the system, it is necessary to secure the specification of the configuration machine as high as possible.
Memory
The physical memory of the target system requires at least 4 GB, and the memory for the send buffer must be calculated separately for asynchronous replication. Memory for the send buffer requires a minimum memory capacity of 20MB to 100MB.
However, in order to improve replication performance, it is desirable to secure and configure as many physical memory resources as possible.
Recently, replication configuration through VM is becoming common in virtualized environments. The peculiarity of this environment is that the CPU or memory resource situation allocated to individual VMs is not sufficiently allocated. For example, if an individual VM is configured with 2core, 2 to 4 GB of memory, the minimum configuration of bsr will not be met. When a replication environment is configured with a low-spec VM, there may be a context switching delay between bsr engine threads that process replication, and a network keep alive (ping) delay between both nodes of replication may occur frequently. Even if bsr operates in such an environment, there is no problem in basic operation, but if the I/O load increases or the frequency of occurrence of interrupts in the HW layer of the system increases, the overall performance of the VM decreases, and bsr also affects the operation accordingly. .
There is no special solution to this problem other than to free up system configuration resources.
Disk
Basic installation space
It requires about 200MB to install all the binary execution modules of bsr, and 1GB is required to store the log of bsr, which requires about 2GB of disk installation space.
Mirror Disk
Theoretically, the capacity of the mirror disk of bsr is unlimited, but the size of the mirror volume we verified is 40TB. Limit the size of the maximum mirror volume to 40 TB.
Meta Disk
Depending on the capacity of the replication volume, you need to estimate the capacity of the metadisk. It requires about 33MB of meta disk space per 1TB of the replication volume, and for more accurate size, see Metadata Size Estimation.
Network
In a recent corporate environment, mirroring on a local network is generally configured with a bandwidth of 1 Gbps to 10 Gbps, and a remote replication environment (Disaster Recovery) for DR (Disaster Recovery) is generally operated with a lower bandwidth. That is, it is applied to a wide range of network environments from very low bandwidth (10 ~ 100Mbps) to high bandwidth. However, because replication in a low-band network environment is bound to affect replication performance due to bandwidth limitations, consider such as linking replication accelerators for performance improvement.