Starlight

From HacDC Wiki
Revision as of 22:36, 14 May 2016 by Mirage335 (talk | contribs) (Recommendations)

Jump to: navigation, search


Simple project server, comparable to Shimmer. Increased emphasis on performance and redundancy.

Most likely, this server will continue operating for several years, even as newer and better servers supplant it.

For discussion purposes, server is nicknamed "Starlight".

ChiefAdmins

  • Julia "juri" Longtin
  • Matthew "mirage335" Hines

Support

#hacdc on irc.freenode.net (or via chat.hacdc.org)

Login

On any unix terminal emulator, enter the command:

ssh <userName>@starlight.srv.hacdc.org -p ####

On other platforms, try applications like PuTTY with similar settings. Local connections (within HacDC's network) will need to use IP address 192.168.14.254 .

Recommendations

  • Set restrictive permissions on directories belonging to you.
  • Create a directory for yourself on the fast array at "/mnt/fast/users".
  • Physically, disk array consists of six, 4kB sector size, devices. Try to keep blocksize greater than 24kB - ie. "dd if=/dev/zero of=./test bs=24576" .
  • Use fast array for I/O intensive active jobs (eg. compilation, statistics, simulation). Fast array provides maximum speed, theoretically sustaining upwards of 900MB/s or 1000 IOPS.
  • Use root filesystem (eg. "/home", "/var/www/html") for lightweight services including important data (eg. MediaWiki, git, email). Root filesystem provides maximum durability, surviving 2/6 disk failures.
  • Periodically backup (rsync) important data from fast array to root filesystem.
  • Backup especially critical data (eg. databases) offsite (eg. dropbox).

HacDC admins are happy to help, and may be able to provide assistance with other services (eg. offsite backup).

CommandReference

Routinely important commands unique to this server documented as follows.

Users

List

List OpenVZ VMs created for you.

cat ~/hovzList

Startup

sudo /usr/sbin/vzctl start <name>

Shutdown

sudo /usr/sbin/vzctl stop <name>

Console

Opens command line of running VM <name> .

sudo /usr/sbin/vzctl enter <name>

Root (Admin)

hostedOpenVZ

  • ./hovzNewUser <userName> # Creates user account with default OpenVZ VM and permissions.
  • ./hovzDelUser <userName> # Deletes user account, associated VMs, and associated OpenVZ permissions.
  • ./hovzNewVM <userName> <VM_Number> <dist> # Creates VM accessible to non-root user <userName> . Dist is often"debian-7.0-x86_64-minimal" .
  • vzctl set CTID --ram 128M --swap 256M --save
  • vzctl set CTID --diskspace 4G:4.2G --save

Autostart

Through normal reboots, host will suspend/resume any guest VMs.

iptables

Investigation

  • iptables -t nat -L -n -v #Lists port forwarding rules.
  • iptables -t nat -F #Deletes port forwarding rules.
  • iptables -D PREROUTING 1 #Deletes port forwarding rule.

Forwarding

Specific
/sbin/iptables -t nat -A PREROUTING -p tcp -i eth0 --dport 20283 -j DNAT --to 10.174.10.5:22

Persistent

Package iptables-persistent has been installed. Upon installation, existing iptables rules were saved. Edit /etc/iptables/rules.v4 .

ReInstall

Characteristics

  • CPU - Dual Processor, Octo-Core, Intel Xeon X5355
  • RAM - 48GB ECC
  • HDD Bulk Array - 20TB RAID6
  • HDD Fast Array - 5TB RAID0, Estimated 900MB/s, 1000 IOPS.
  • Hostname - HacDC-shared-m335-2
  • FQDN - HacDC-shared-m335-2.srv.hacdc.org

Redundancy (RAID)

Root filesystem is comprised of six WD60EZRX (WD Green 6TB) disks in a RAID6 (dual-parity array). Disks were intentionally purchased from diverse sources. Data will not be lost unless more than two drives in this array fail simultaneously.

Fast filesystem has worse than no redundancy, being a RAID0 stripe across the front of each disk.

Internal backups and some spare hardware are kept to minimize potential downtime. Disk failures are generally expected to be repaired without shutdown.

Policies

Permissions

Root

HacDC members with a demonstrable need or willingness to manage non-root users may be given root access. Imperative that root users do not jeopardize uptime.

Shell

All HacDC members are welcome to non-root shell accounts, directly provided by the server.

OpenVZ

All HacDC members are welcome to OpenVZ Virtual Machines. Resources, including CPU, disk space, and external network ports, will be allocated on an as-needed first-come-first-serve basis.

Root users, please use the provided hostedOpenVZ scripts. Following the naming conventions set therein helps account for which resources belong to whom.

Notifications

Internal server email will notify users, if feasible, on the following schedules, subject to change.

  • Three days before planned downtime exceeding one hour.
  • One week before planned permanent downtime (obsolescence).

Forwarding to another email address is possible with the following command.

echo 'person@mail.com' > ~/.forward

Removal

  • Up to three months before removal of ex-member accounts. Exceptions on a case-by-case basis.
  • Compromised accounts will be immediately removed or disabled as discovered.
  • Excessive resource use, including disk space consumption, may be terminated, particularly if account holder is not responsive to inquiries.

DataLoss

  • Failure of more than two disks will result in unrecoverable loss of data on this server.
  • Failure of any disk on fast array will result in unrecoverable loss of data from that partition.
  • Removed accounts or terminated services may result in immediate, permanent deletion.
  • As array repair procedures are rarely done, catastrophic mistakes are possible.
  • Virtual Machines are stored on fast array by default, periodically backed up internally.

Privacy

Machine is security is not especially tight. Sysadmins may investigate possible abuse. Privacy may exist, but is not a reasonable expectation.

AcceptableUse

Disk

Vast quantities of disk space are available. Still, please be considerate, and understand that on-mission HacDC activities may be given priority.

Sharing

Sharing of account resources is permitted, however, additional resources will be allocated according to individual member needs for specific purposes. As a reminder, compromised accounts will be immediately removed or disabled as discovered.

Bandwidth

Although HacDC has a high-capacity 175/15Mbit link, it is shared with other tenants. Please be courteous. If internet bandwidth use is required for downloading large files, between 2200EDT and 0600EDT is best.

Hard bandwidth limits have not been set to ease administration of local file servers. However, please configure applications to limit maximum bandwidth use where possible, particularly for web servers.

  • NOTE: If your bandwidth use is too high during normal hours, the church administrator will cut bandwidth available to the whole subnet and will call mirage335, juri_, Ethan Waldo, or other admin team members to resolve the issue (no one will be happy).

Special Services

HTTP/HTTPs

Ports 80/443 are available through reverse proxy. Please setup a relevant domain name (eg. *.member.hacdc.org) through FreeDNS or other service, and contact the HacDC admin team for assistance.

NamingConvention

Preferred network names for participating machines and virtual machines.

Physical

Hostnames

HacDC-shared-m335-2

  • HacDC - Identifies machine as HacDC or HacDC member property on the local network.
  • shared - One of private, restricted, shared. Private = one member only (eg. RasPi). Restricted = limited access (eg. HacDC web server). Shared = shared resources (ie. remote shells).
  • m335 - Abbreviated member name or screen name. Full contact details should be written on the physical machine.
  • 1 - Unique identifier.

FQDNs

HacDC-shared-m335-2.router.hacdc.org

Virtual

Hostnames

mirage335-1

  • mirage335 - Local username.
  • 1 - Unique machine identifier.

FQDNs

mirage335-1.HacDC-shared-m335-2.router.hacdc.org

Timezone

EST/EDT aka US Eastern, America/NewYork, or "Eastern"

Workarounds

SSH KeepAlive

Due to limited bandwidth, SSH sessions may freeze. To prevent this, consider the following to configuration, appended to client-side ~/.ssh/config .

Host *
  ServerAliveInterval 30

Disclaimer

No guarantees. Admins are expected to make best efforts toward reliability, security, and privacy. Monitoring may include without limitation system health, resource consumption, and authentication failures, and the like. More intrusive monitoring, such as of user filesystems, should be avoided if possible.

Excepting the case, reasonably requsitioned as a supply, the server is property of Julia Longtin. Administration is at the discretion of her and designated admins.


Credits

Julia Longtin - Donated core hardware.

Reference