Share This [+]
February 11th, 2010 by Jason C.
There will be many times when you’ll need to initialize or reinitialize a subscriber in a transactional replication configuration with a new snapshot. This is usually the case when creating new publications, creating a new snapshot because changes are made to a publication, or when recovering from replication failures. The snapshot process can be rather resource-intensive depending on your server hardware and consists of capturing the schema and all of the data for the tables to be replicated into text files. These text files are created in the snapshot directory that was designated during the initial replication configuration and then bulk copied into the subscriber database.
I have seen replication snapshots cause the publishing server to become unresponsive in worst case scenarios. Although I’ve found these circumstances to be rare, it is something to be taken into consideration. This kind of side effect is usually seen in lower-end servers that do not have adequate hardware resources combined with other underlying factors. You can imagine the chaos this would cause during normal business hours in a production environment. You could schedule a snapshot to occur after hours to avoid impacting your users, but suppose you are required to add a few new tables to the publication so you can get those updated TPS reports to management before 5 o’clock. Now you’re left with two options: either you slow the productivity of your office while the snapshot process completes, or you tell management that they’ll have to wait until after hours. Luckily, there is a way out of this nightmare.
The Initialize From Backup setting allows a backup of the publication database to initialize the subscriber without the need of a snapshot. The setting can be found in the subscription options page of the publication properties dialog box. Select a value of True for the Allow initialization from backup files option to enable this functionality. The remaining steps to initialize the subscriber from a backup are as follows:
Read the full post »
Tags: backups, replication, snapshots, SQL, SQL Server Replication
Share This [+]
February 9th, 2010 by INetU
EdgeCast Networks, the superior, cost-effective rich media content delivery network (CDN), and INetU, a managed hosting provider, today announced the availability of global content delivery services to all INetU customers.
This agreement opens EdgeCast’s worldwide content delivery network to INetU clients, enabling any INetU customers to instantly deploy web applications, site content, and media streams via any of EdgeCast’s sixteen points of presence around the world. This will mean dramatic increases in performance and the worldwide availability of customer sites.
“EdgeCast and INetU have something very important in common, and that is a culture of commitment to going above and beyond for every customer,” said James Segil, president of EdgeCast Networks. “This partnership is an example of that commitment in action - INetU’s customers sought a way to overcome the bottlenecks of long distance site performance, and INetU delivered. Now their customers have a true one-stop-shop for quickly delivering their content and applications to any computer around the world.”
INetU’s managed hosting customers previously served all content - media streams, web applications, and hosted files - from their servers in Allentown, PA. While the servers were connected to top tier Internet providers via fiber optics, latency for time sensitive applications to remote parts of the globe was challenging for some customers.
Read the full story about our CDN partnership.
Tags: cdn, managed hosting, news
Share This [+]
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.
Read the full post »
Tags: application availability, downtime, high availability, managed hosting, uptime
Share This [+]
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
Read the full post »
Tags: Hyper-V, monitoring, virtual machines, virtualization
Share This [+]
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.
Read the full post »
Tags: array, controller, database, DB, I/O, performance, RAID, RAID-10, RAID-5, rebuild, spindles, storage
![[]](/imagesb/reflection02.gif)