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Supports Windows 2012 or higher, Linux CentOS 6.4, Ubuntu 16.04 LTS or higher x64 environment.
OS | CPU Architecture |
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Windows 2012 or higher | x64 |
RHEL / CentOS 6.4 ~ 8.4 | x64 |
RHEL / Rocky 8.5 or higher | x64 |
Ubuntu 16 LTS or higher | x64 |
ProLinux 7 or higher | x64 |
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.
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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 For types of filesystems 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 problemit behaves as a traditional full sync.
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 system typically starts paging virtual memory when memory usage exceeds 70%, depending on kernel settings. Because paging degrades system I/O performance, it is beneficial for replication to be configured to always have at least 30% free physical memory so that paging is suppressed.
The memory
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used by BSR is primarily required for buffering purposes and is determined by the maximum write request value (max-req-write-count) in the BSR settings and the size of the transmit buffer. Below is an example for a Windows environment.
For synchronous without a send buffer
At the default setting for write requests (10k), use a maximum of 1.5GB per resource.
At the write request maximum setting (100,000), use a maximum of 3 GB per resource.
For asynchronous with a 1GB send buffer setting, use a maximum of 3GB per resource in the
Use a maximum of 2.5 GB per 1 resource at the write request default setting.
Use a maximum of 4 GB per resource at the Write Request Max setting.
For a server with 64 GB of physical memory, approximately 20 GB (30%) of memory free space is required, and of the memory space used, a maximum of 2.5 GB per 1 resource is required for asynchronous by default.
If you don't have that 30% free memory, you'll have to accept a degradation in basic I/O performance due to paging.
The 3 to 4 GB NP memory usage per resource required by replication should be kept free, otherwise you will run out of memory, which can lead to failure.
Transmit buffer size
The size of the transmit (TX) buffer on the local side is ideally set to a number that allows for the free transfer of locally generated I/O data to the remote side. It is found by the following equation
Maximum size of transmit band per time (s) * Transmit timeout time (s)
For example, for a 1 Gbps band, you can get (about 100 MB/s * 5 s) = 500 MB, and you can set a buffer of 500 MB to 1 GB.
If you need to consider the variable bandwidth of the WAN segment, you can add more capacity to the above size plus the time (s) to tolerate the WAN bottleneck delay, or buffer it with a proxy (DRX). Typically, WAN leg buffering is specified at 5 to 10 times the TX buffer.
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When paging occurs can vary depending on your system's memory capacity, platform, and OS version. The 70% figure described above is typical and should be understood in the context of your environment. BSR memory usage on Linux is similar or less than on Windows. It uses a bit more memory on Windows due to some differences in the replication architecture. |
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Recently, replication configuration configurations through VM is VMs are becoming more common in virtualized environments. The peculiarity of this environment is that virtualization environments, but there are cases where the CPU or memory resource situation resources allocated to individual VMs is are not sufficiently allocatedsufficient. For example, if an individual VM is configured with 2core, 2 to 4 GB of memory, 1 core CPU and 1~2GB memory, it will not meet the minimum configuration specifications 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 end VMs, performance delays due to frequent CPU context switching, and thus inter-node communication (keep alive) delays, become frequent. Operating replication on VMs in this environment has severe limitations. There is no solution to this problem other than to free freeing 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
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disks
Theoretically, the capacity of the a BSR's 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 TBthe actual disk capacity is limited to 10 TB. At higher capacity, the meta-area corresponding to the mirror disk capacity grows along with it, and the operation (Attach) that needs to process the entire meta-disk becomes time-consuming and impedes operations.
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Multi-volume Storage corresponding to one service task is often composed of multiple volumes. In this case, it is necessary to treat these volumes as one resource. In this way, operating multiple volumes by tying them to one resource is called a multi-volume configuration. When operating resources as multiple volumes, the data processing buffer queue is operated as a single queue, thereby serializing the service's write I/O order to the disk volume to ensure service consistency. There is no limit to the number of multiple volumes (maximum 65535), but in reality, as the number of volumes increases, the queue buffer delay may become severe and difficult to control. It is realistic to configure no more than 4 to 5 volumes in a 10G network. |
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
throughput
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.
ports
The mirroring ports for replication (specified in the configuration file) must be open. On Windows, additionally TCP loopback ports 5678, 5679 must be open for control.
Storage provisioning
Of the storage provisioning methods on the virtualisation platform, only thick provisioning is supported. For thin provisioning, the disk space reclamation feature is incompatible with block replication operations.
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It is only supported for the THICK provisioning method of storage provisioning. Thin provisioning environments with disk space reclamation are not compatible with BSR.
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Disk space reclamation in THIN provisioning can cause data inconsistency issues in certain situations. To use a THIN environment, you must disable space reclamation. |