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February 3rd, 2010 by Jeff P.
In a perfect world your website would be available all day, every day, completely without fail. In reality, downtime happens. Hosting providers like to guarantee uptime, but what does that really mean? Here are three things your hosting provider isn’t telling you about 100% uptime:
#1 - Uptime is your responsibility, too.
When you talk about uptime, you mean that your site is available to your audience. When a hosting provider talks about uptime, they mean network uptime, and possibly hardware availability if you are using shared resources instead of dedicated servers.
In a dedicated hosting environment, device availability and fault tolerance are your responsibility. If a hard drive fails, did you purchase a RAID configuration to protect yourself? Did you elect to build out a database cluster? Redundant firewalls?
Application availability is also affected by your developers. In many cases, changing a single file can drop your site off the radar, even though the pipes are live and the hardware is functional. Do you have a separate development area to prevent this kind of thing from happening? What controls do you have in place to make sure that only stable edits are pushed live?
#2 - Downtime happens. There is no preventing it.
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Tags: application availability, downtime, high availability, managed hosting, uptime
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November 4th, 2009 by Chris K.
Minimizing traffic loss and preventing downtime in a server migration comes down to planning. If you do not take care when you move your website, significant outages can take place. This translates to a number of potential negative consequences for your business including revenue loss, impact on search engine rankings, and damaged customer relationships.
Most failed server migrations can be traced back to poor planning and/or a lack of careful execution of a plan. If planned and executed right, successful migrations can result in no downtime or data loss. At minimum, you can severely reduce the impact of a server transfer by following this easy 5 step approach.
What you need to pull this off:
- Server environments running parallel at your current host and new host. This is a minimum requirement to transition smoothly because taking your old servers down before uploading your data on new servers equals major downtime.
- The ability to control DNS transfer at the record level with the ability to control Time to Live (TTL) – either through a control panel or via helpful hosting company admins. This is critical in minimizing the time it takes the rest of the Internet to recognize your DNS changes.
- Attention to detail, because without it you may lose critical data.
Step 1: Setup DNS at your new host before the cutover.
A great way to execute this transfer is to set up DNS at your new host before the “real” DNS cutover. In the new host’s name servers, point the appropriate DNS records related to what you are moving (http, etc.) to your current servers at your current host and set TTL reasonably low (about 10-60 minutes). Most networks on the Internet will recognize DNS changes based on Time to Live, which means if you set this up right, once you make that real cutover traffic will flow to the new servers much quicker. By default, this type of transfer would take anywhere from 12-24 hours to be recognized. That is a lot of time to have customers visiting both sets of servers.
Step 2: At the registrar, point your name servers to the new host.
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Tags: dns, migrate, uptime
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October 28th, 2009 by Scott W.
Be careful about the distinction between uptime and high availability. One should be the goal of your server infrastructure. The other is just a geek bragging right.
Many system administrators will brag about their systems having high uptimes. The uptime of a system is how long it has been running without a reboot. The current longest running uptime, as being tracked by Uptimes Project, is a VMS cluster that has been up just shy of 12 years as of the date this blog was published. Since we strive for 100% uptime, shouldn’t this be an impressive record to share with all of your friends as an exemplary form of sysadmin kung-fu? Actually no, never rebooting your systems fosters a “if it ain’t broke don’t fix mentality” that carries quite a few risks:
- First, if a machine has not been rebooted kernel, OS, and application patches are probably not being kept up-to-date. In today’s age on the Internet this can be a very dangerous practice. Your systems may be vulnerable to known exploits. In addition, if you run into problems with your system, your vendor will require applying recommended patches as a first course of action. It’s better to have these things taken care of before adding to work during a problem. We’ve seen out of date Windows servers need over 4 hours of patches requiring multiple reboots.
- Second, you’re potentially leaving around rotten Easter eggs. By rotten Easter eggs I mean changes to systems that don’t make it through a reboot: production services that should be running, startup scripts that do not work properly, IP addresses that have been added, speed/duplex issues that have been resolved since the machine has been up. So worst case scenario is that your server goes down (either planned or unplanned) and after the reboot you have a server with poor network performance, not all IP addresses are alive, and the database application isn’t running. If the reboot was not planned (a crash) this adds to the confusion when trying to bring the system back online.
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Tags: high availability, uptime
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August 26th, 2009 by Scott W.
Today’s websites are expected to be available 100% of the time. The Internet has connected a global marketplace of consumers and businesses where any amount of unplanned downtime can be disastrous for retail orders and/or reputation. If you desire to have a highly available website, study this list of the three reasons websites fail:
1. Management, developers and administrators aren’t invested in disciplined change management.
If you want high availability, you must manage your changes. A stack of shiny hardware alone does not provide uptime. So the last time you suffered a web site outage and during the problem your developers and admins were all claiming innocence that nothing changed, well, odds are they are lying. After you discover the cause, you get the same song and dance, “Oh, well that shouldn’t have caused a problem.”
Anyone with experience in IT will intuitively understand this truth. Luckily, we also have some data to back this up. Donna Scott, VP & Research Director, Gartner, notes that, “80 percent of unplanned downtime is caused by people and process issues, including poor change management practices, while the remainder is caused by technology failures and disasters.” I think our unwillingness to address this truth directly is because we’d rather blame some “system” or “hardware” for root cause rather than the people who should be held accountable for uptime. Throwing money at software and hardware will not solve people problems. Buying the super redundant n+4 failover hot-cold-warm standby solution won’t fix the problem that “Jimmy type-twice-think-once” has root (Administrator) access to the production environment.
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Tags: development cycle, uptime, virtualization
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June 17th, 2009 by Jeff P.
Yesterday Opera Labs unveiled Opera Unite, which essentially turns the Opera web browser into a web server. Over at their blog, Lawrence Eng writes:
Our computers are only dumb terminals connected to other computers (meaning servers) owned by other people — such as large corporations — who we depend upon to host our words, thoughts, and images. We depend on them to do it well and with our best interests at heart. We place our trust in these third parties, and we hope for the best, but as long as our own computers are not first class citizens on the Web, we are merely tenants, and hosting companies are the landlords of the Internet. (http://labs.opera.com/news/2009/06/16/)
But is “landlords of the Internet” an appropriate epithet for hosting companies? Consider for a moment what hosting companies bring to the table:
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Tags: opera unite, security, uptime
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