Open Infrastructure

h1. Uptime objectives

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h2. Introduction

This is an internal (and public) planning document for our data center. It does *not* constitute an SLA (send us an email if you need SLAs). It is used for planning further stability improvements.

h2. Uptime definitons

| %  | Downtime / year |

| 99 |  87h or 3.65 days |

| 99.9 | 8.76h |

| 99.99 | 0.876h or 52.55 minutes |

| 99.999 | 5.25 minutes |

h2. Power Supply

* What: Power supply to all systems

* Setup:

** Core systems are connected to UPS that last between 7-30 minutes

** Virtualisation systems are not (yet) fully connected to UPS (to be finished 2019-07)

* Expected outages

** Prior to full UPS installation: <= 24h/year (99%)

** After UPS installation: 99.9%

*** Probably less, as most power outages are <1m

** Values for 2020/2021 are estimated, need to be confirmed with actual power outages

* Uptime objective

** 2019: 99%

** 2020: 99.9%

** 2021: 99.99%

h2. L2 Internal Network

* What: The connection between servers, routers and switches.

* Setup: All systems are connected twice internally, usually via fiber

* Expected outages

** Single switch outage: no outage, maybe short packet loss (LACP link detection might take some seconds)

** Double switch outage: full outage, manual replacement

* Uptime objectives

** From 2019: >= 99.999%

h2. L2 external Network

* What: the network between the different locations

* Setup:

** Provided by local (electricity) companies.

** No additional active equipment / same as internal network

* Expected outages

** 1 in 2018 that could be bridged by Wifi

** If an outage happens, it's long (digging through the cable)

** But it happens very rarely

** Mid term geo redundant lines planned

** Geo redundancy might be achieved starting 2020

* Uptime objectives

** 2019: >= 99.99%

** 2020: >= 99.999%

** 2021: >= 99.999%

h2. L3 external Network

* What: the external (uplink) networks

* Setup

** Currently 2 uplinks

** Soon 2 individual plus a third central uplink

* Expected outages

** 2019 added bgp support

** Outage simulations still due

* Uptime objectives

** 2019: >= 99.99%

** 2020: >= 99.999%

** 2021: >= 99.999%

h2. Routers

* What: the central routers

* Setup

** Two routers running Linux with keepalived

** Both routers are rebooted periodically -> downtime during that time is critical, but unlikely

** Routers are connected to UPS

** Routers are running raid1

* Expected outages

** Machines are rather reliable

** If one machines has to be replaced, replacement can be prepared while other routers are active

** Rare events, nice 2017 no router related downtime

* Uptime objectives

** 2019: >= 99.99%

** 2020: >= 99.999%

** 2021: >= 99.999%

h2. VMs on servers

* What: Servers host VMs and in case of a defect VMs need to be restarted on a different server

* Setup:

** Servers are dual power connected

** Servers are used hardware

** Servers are being monitored (prometheus+consul)

** Not yet sure how to detect soon failng servers

** So far 3 servers affected (out of about 30)

** Restart of a VM takes a couple of seconds, as data is distributed in ceph

** Detection is not yet reliably automated -> needs to be finished in 2019

* Expected outages

** At the moment servers "run until they die"

** In the future servers should be periodically rebooted to detect broken hardware (live migrations enable this)

** While a server downtime effects all VMs (up to 100 per server), it's a rare event

* Uptime objectives (per VM)

** 2019: >= 99.99%

** 2020: >= 99.999%

** 2021: >= 99.999%

h2. Storage backends

* What: the ceph storage that contains the data of VMs and services

* Setup

** A disk is striped into 4MB blocks

** Each block is saved 3x

* Expected outages

** Downtime happens at 3 failures at the same time in a near time window

** 1 disk failure triggers instant replication

** Disks (HDD, SSD) are ranging from 600GB to 10TB

** Slow rebuild speed is around 200MB/s

** Thus slowest rebuild window is 14.56h

* Uptime objectives (per image)

** 2019: >= 99.999%

** 2020: >= 99.999%

** 2021: >= 99.999%