Administrator’s Command Line Guide

3.1. About Object Storage
3.1.3.2 Name Server
A name server performs the following functions:
• Stores object names and metadata.
• Provides the API for pasting, deleting, listing object names and changing object metadata.
Name server consists of data (i.e. object metadata), object change log, an asynchronous garbage collector,
and asynchronous handlers of incoming requests from different system components.
The data is stored in a B-tree where to each object’s name corresponds that object’s metadata structure. S3
object metadata consists of three parts: information on object, user-defined headers (optional), and ACL for
the object. Files are stored in the corresponding directory on base shared storage (i.e. Acronis Storage).
Name server is responsible for a subset of S3 cluster object namespace. Each NS instance is a userspace
process that works in parallel with other processes and can utilize up to one CPU core. The optimal number
of name servers are 4-10 per node. We recommend to start with creating 10 instances per node during
cluster creation to simplify scalability later. If your node has CPU cores that are not utilized by other storage
services, you can create more NSes to utilize these CPU cores.
3.1.3.3 Object Server
An object server performs the following functions:
• Stores object data in pools (data containers).
• Provides an API for creating, reading (including partial reads), writing to, and deleting objects.
Object server consists of the following:
• information on object’s blocks stored on this OS,
• containers that store object data,
• asynchronous garbage collector that frees container sections after object delete operations.
Object data blocks are stored in pools. The storage uses 12 pools with blocks the size of the power of 2,
ranging from 4 kilobytes to 8 megabytes. A pool is a regular file on block storage made of fixed-size blocks
(regions). In other words, each pool is an extremely large file designed to hold objects of specific size: the
first pool is for 4KB objects, the second pool is for 8KB objects, etc.
Each pool consists of a block with system information, and fixed-size data regions. Each region contains has
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