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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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January 27th, 2010 by Andrew H.
Virtualization offers advantages that take many forms, but with it can come challenges because virtualization lies. The basic premise of virtualization is that the operating system running on a virtual machine is presented with hardware that doesn’t really exist. Performance monitoring on any platform can be complicated and influenced by a variety of factors, but measuring performance on a system that involves lies is even harder. Luckily, most virtualization products have special ways to gather more accurate system performance. This article will focus on Hyper-V, but similar tools are available for other platforms.
Disk
Since Hyper-V supports dynamically expanding disks, the disk capacity of the virtual machine can be misleading. When dynamically expanding disks are used, plenty of free capacity might appear to be available on the virtual machine, but the host’s free space could be very low. For this reason, it’s important to monitor the available capacity of the Hyper-V host as well as the virtual machines. Disk performance can be monitored accurately in Hyper-V virtual machines the same way as physical machines.
Network
Multiple virtual machines can share the same network adapter. Since each virtual machine can only report its own usage, it’s important to watch the usage of all virtual machines. VMs will also report that they are on a 10gbps connection; however, the bandwidth of the link will always actually equal the bandwidth of the external link.
Processor
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Tags: Hyper-V, monitoring, virtual machines, virtualization
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January 20th, 2010 by Rich H.
RAID-5 was long hailed as the enterprise-level storage solution and a fit for nearly every application. The truth is, RAID-5 was designed back in the 80’s to save cost without completely sacrificing redundancy. Back then the cost per byte for storage on enterprise-class drives was so expensive that researchers were scrambling for a solution to store more data for less money.
Let’s say you needed 100MB of storage space and disk-level redundancy. Let’s also say, a 20MB SCSI drive cost $1,000.00. Before RAID-5, you’d buy 10 drives, create 5 RAID-1 arrays at 20MB each, and split your data set up to fit across these 5 separate arrays. Not only is this expensive at $10,000.00, but the storage space you require is split across 5 arrays. With RAID-5, 6 20MB disks gave you 100MB of space, and redundancy. That saves $4,000.00 per storage unit implemented! Sure, there were caveats, but with those kinds of savings, nobody was paying attention.
Welcome to the 21st century. The database is king, and everyone wants performance! Unfortunately, one of RAID-5’s biggest caveats is sacrificing performance, and developers and admins are finally starting to notice. Let’s take a look at the 5 biggest caveats of the RAID level most synonymous with enterprise storage for so many years:
- Performance, Performance, Performance! RAID-5 has significant write penalties all the time due to the requirement for parity calculation. Most implementations also suffer poor read performance, even though RAID-5 proponents consider this one of the “strengths” of RAID-5.
- Rebuild times are horrifying slow. Try days instead of hours for large storage arrays due to the need to read, calculate parity and write every disk in the array for each megabyte rebuilt. This can literally translate to days of downtime for a single disk failure depending on the I/O performance required for the storage to be usable.
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Tags: array, controller, database, DB, I/O, performance, RAID, RAID-10, RAID-5, rebuild, spindles, storage
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January 13th, 2010 by Jeff P.
Here are some disturbing statistics:
- A recent Hotmail security breach revealed that an overwhelming number of users are using predictable, insecure passwords:
- 61% of passwords were either only lowercase letters or all digits (examples: iloveyou or 123456).
- 20% of passwords were six or fewer characters.
- An estimated 1 in 9 people use one of the Top 500 passwords posted on WhatsMyPass.com
- 1 in 50 people are estimated to use one of the Top 20 passwords, among which are password, 123456, and qwerty.
- Many of the Top 500 passwords are simple dictionary words, curse words, or common first names.
- 60% of web users only have one password that they use for all of their online accounts, including Facebook, PayPal, email, and banks, according to a recent study.
A typical strong password guide looks a little something like this:
- At least 8 characters long
- At least three of the following:
- lower case letter
- capital letter
- numeral
- special character
But this really seems to miss the point. For example, go to Microsoft’s password checker and type in this password: qwerty123456! The checker gives this password strength “Best.” But is it really?
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Tags: hacking, password policy, security
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January 6th, 2010 by Scott W.
You can’t open a browser or read a technology magazine without seeing something about the cloud. What is the cloud and what is the big hubbub? I am not able to pinpoint a definition of the cloud, but I think the impact of the cloud is getting clearer. Computing and communication will be sold on a usage basis much like water and electricity. This clarity elucidates a fascinating point that in our future we will buy more services and experiences than products and physical objects. If this comes to fruition, are we losing out on the physicality of life? Or have objects always been a symbol of experience? Because the symbols can be converted into zeroes and ones and sent across the world in seconds, does it mean they are less meaningful than physical symbols?
Computing and communication previously required a significant investment to have useful tools. Today, most mobile phone providers will give you a phone and charge you for the service for committing to a one or two year contract. A good computer system can now be purchased for around $500. Instead of buying shrink wrapped software, you can get your e-mail for free, and pay a monthly or yearly fee for backups, customer relationship management, and home finance software. Companies, of course, love subscriptions for the reoccurring revenue and consumers enjoy fixed rate fees over time instead of large one-time charges.
So with these enablers, we can now send photographs to each other on phones and computers. We can send digital cards and flowers to each other. Music no longer needs to be purchased at a store on a shiny disc of digital data. So what are we buying today? What were we paying for in times past?
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Tags: cloud, virtualization
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