mirror of
https://github.com/schoebel/mars
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187 lines
4.3 KiB
Plaintext
187 lines
4.3 KiB
Plaintext
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\pdf_title "MARS Manual"
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\pdf_author "Thomas Schöbel-Theuer"
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\end_header
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\begin_body
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\begin_layout Standard
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MARS is a block-level storage replication system for long distances / flaky
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networks under GPL.
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\end_layout
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\begin_layout Standard
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It is a key component for achieving
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\series bold
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geo-redundancy
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\series default
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under Linux, for example Disaster Recovery (DR) at datacenter granularity,
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and/or Location Transparency (LT) at VM / LV granularity.
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\end_layout
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\begin_layout Standard
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It can help to increase
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\series bold
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reliability
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\series default
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via Sharding, and to
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\series bold
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save cost
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\series default
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by optional support for local storage in addition to network storage.
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\end_layout
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\begin_layout Standard
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It eases
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\series bold
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load balancing
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\series default
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and
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\series bold
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background migration of data
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\series default
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, even over long distances.
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\end_layout
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\begin_layout Standard
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MARS runs as a Linux kernel module.
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The sysadmin interface is similar to DRBD, but its internal engine is completel
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y different from DRBD: it works with transaction logging, similar to some
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database systems.
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\end_layout
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\begin_layout Standard
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Therefore, MARS can provide stronger consistency guarantees.
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In case of network bottlenecks / problems / failures, the secondaries may
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become outdated (reflect an elder state), but will not become inconsistent.
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In contrast to DRBD, MARS preserves the order of write operations even
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when the network is flaky (Anytime Consistency).
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\end_layout
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\begin_layout Standard
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The current version of MARS supports k > 2 replicas and works asynchronously.
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Therefore, application performance is completely decoupled from any network
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problems.
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Future versions are planned to also support synchronous or near-synchronous
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modes.
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\end_layout
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\begin_layout Standard
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MARS supports a new method for building Cloud Storage / Software Defined
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Storage, called
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\series bold
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LV Football
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\series default
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.
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It comes with some automation scripts, enabling a similar functionality
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than Kubernetes, but devoted to stateful LVs over
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\series bold
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virtual LVM pools
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\series default
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in the petabytes range.
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\end_layout
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\begin_layout Standard
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MARS is in production since 2014, and on thousands of Linux servers replicating
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petabytes of data.
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\end_layout
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\end_body
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\end_document
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