caisan

原文：架构师

架构师（JiaGouX）

我们都是架构师！

分布式系统中经常需要考虑对象（或者记录、文件、数据块等）的读写的顺序以及并发访问问题。通常来说，如果两个对象没有共享的资源，就可以进行并发的访问，如果有共享的部分，就需要对这部分资源进行加锁；而对于同一个对象的并发读写（尤其是并发写更新时），就需要注意顺序性以及并发访问的控制，以免数据错乱。本文主要对ceph中对象读写的顺序及并发性保证机制进行介绍。

PG的概念

原文：架构师

架构师（JiaGouX）

我们都是架构师！

ceph后端支持多种存储引擎，以插件式的方式来进行管理使用，目前支持filestore，kvstore，memstore以及最新的bluestore，目前默认使用的filestore，但是因为filestore在写数据前需要先写journal，会有一倍的写放大，并且filestore一开始只是对于机械盘进行设计的，没有专门针对ssd做优化考虑，因此诞生的bluestore初衷就是为了减少写放大，并针对ssd做优化，而且直接管理裸盘，从理论上进一步减少文件系统如ext4/xfs等部分的开销，目前bluestore还处于开发优化阶段，在jewel版本还是试用版本，并且最新的master相比jewel已经做了大的重构，预期会在后续的大版本中稳定下来成为默认的存储引擎。本文基于master分支对bluestore存储引擎进行分析。

bluestore整体架构

vstart

setup

start:

MON=1 OSD=1 MDS=0 MGR=0 RGW=1 ../src/vstart.sh -n -d -o rgw_max_objs_per_shard=50 -o rgw_reshard_thread_interval=60

verify the number was set, and that dynamic reshard is enabled:

bin/ceph -c ceph.conf daemon out/radosgw.8000.asok config get rgw_max_objs_per_shard
bin/ceph -c ceph.conf daemon out/radosgw.8000.asok config get rgw_dynamic_resharding

Running Tests Locally

you run the tests locally from your "build" directory in your test environment
then you need to add a "test_multi.conf" file:

[DEFAULT]
num_zonegroups=1
num_zones=1
num_ps_zones=0
gateways_per_zone=1

Setting up Qemu with a tap interface

There are two parts to networking within QEMU:

The virtual network device that is provided to the guest (e.g. a PCI network card).
The network backend that interacts with the emulated NIC (e.g. puts packets onto the host's network).

	#!/usr/bin/env bash
	#
	# Usage:
	# s3-get.sh <bucket> <region> <source-file> <dest-path>
	#
	# Description:
	# Retrieve a secured file from S3 using AWS signature 4.
	# To run, this shell script depends on command-line curl and openssl
	#
	# References:

	#!/usr/bin/env bash
	#
	# Usage:
	# s3-get.sh <bucket> <region> <source-file> <dest-path>
	#
	# Description:
	# Retrieve a secured file from S3 using AWS signature 4.
	# To run, this shell script depends on command-line curl and openssl
	#
	# References:

	# Copyright 2017 Cloudbase Solutions SRL
	# All Rights Reserved.
	#
	# Licensed under the Apache License, Version 2.0 (the "License"); you may
	# not use this file except in compliance with the License. You may obtain
	# a copy of the License at
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software

	#!/bin/bash

	## Updates to this file are now at https://github.com/giovtorres/kvm-install-vm.
	## This updated version has more options and less hardcoded variables.

	# Take one argument from the commandline: VM name
	if ! [ $# -eq 1 ]; then
	echo "Usage: $0 <node-name>"
	exit 1
	fi

	qemu-img create -f qcow2 /pool/vms/xp.qcow2 50G

	sudo virt-install --connect qemu:///system -n xp -r 512 --disk path=/pool/vms/xp.qcow2,size=50 \
	-c /pool/iso/windows/en_windows_xp_professional_with_service_pack_3_x86_cd_vl_x14-73974.iso \
	--graphics vnc,listen=0.0.0.0,port=65322 --noautoconsole \
	--os-type windows --os-variant winxp