Ask the Experts

Ask the Experts

• Star schema vs snowflake schema: Which is better?

  Yahoo’s data and business intelligence architect, Rohit Chatter, answers the latest debate, Star versus Snowflake schema, by breaking down the differences, one aspect at a time  Continue Reading

• Securing big data: Architecture tips for building security in

  Expert Matt Pascucci advises a reader on securing big data with tips for building security into enterprise big data architectures.  Continue Reading

• Techniques for preventing a brute force login attack

  A brute force login attack can enable an attacker to log in to an application and steal data. Rob Shapland explains how to prevent brute force attacks.  Continue Reading

• File upload security best practices: Block a malicious file upload

  Do your Web app users upload files to your servers? Find out the dangers of malicious file uploads and learn six steps to stop file-upload attacks.  Continue Reading

• Session fixation protection: How to stop session fixation attacks

  Session fixation attacks rely on poorly managed Web application cookies. Rob Shapland answers a reader’s question on session fixation protection.  Continue Reading

• The reasons for missing hard drive space on storage arrays

  If you installed disk and didn’t get the capacity you expected, the missing hard drive space can be a result of operating system calculations, formatting, RAID and use of hot spares.  Continue Reading

• Adding an old hard drive to RAID sets on servers

  When adding an old hard drive to RAID sets on servers, it’s important to account for factors such as the number of drive bays in the host. See how to configure the drives to the appropriate RAID format for the workload.  Continue Reading

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  summary text for test CW eoc answer.  Continue Reading

• Fibre Channel over IP: What it is and what it’s used for

  Fibre Channel over IP bundles Fibre Channel frames into IP packets and can be a cost-sensitive solution to link remote fabrics where no dark fibre exists between sites.  Continue Reading

• Key steps for a successful SAN migration

  For a successful SAN migration, it’s key to understand your current environment and the future state of the SAN, as well as to carry out a testing phase against each platform and migration strategy.  Continue Reading

• Choosing a RAID level depends on capacity needs and data criticality

  In this Ask the Expert, Steve Pinder talks about which RAID level to choose, depending on the criticality of your data or the capacity required.  Continue Reading

• Planning a NAS migration project

  NAS migration requires careful planning around the needs of your organization. In this Ask the Expert, find out which approach to use for an effective migration.  Continue Reading

• RAID 5 explained: Sharing a 10 MB file among 5 drives

  Find out how RAID 5 handles sharing data shares data in a 10 MB file among five drives, including how striping and parity data figure into the equation.  Continue Reading

• Synchronous vs asynchronous replication: Order of events during data writes

  Learn about the order of events during data writes in synchronous vs asynchronous replication.  Continue Reading

• How to set up a Dell EqualLogic configuration in a VMware environment

  Find out what the key steps are for setting up a Dell EqualLogic configuration for an iSCSI SAN in a VMware virtual server environment.  Continue Reading

• SAN troubleshooting: What are the key steps and best practices when troubleshooting a SAN?

  Learn which tools you need to perform SAN troubleshooting, which metrics point to a sign of trouble, and why granular and regular data collection is important.  Continue Reading

• How does the RAID 5 calculation work?

  Learn how to determine how much capacity you'll have in a RAID 5 drive configuration.  Continue Reading

• What does the parity bit do in RAID?

  Find out how the use of a parity bit protects RAID groups and how it's used as a method for error detection.  Continue Reading

• RAID 4 vs RAID 5: Which one costs more to implement?

  RAID 4 vs RAID 5: Which one costs more to implement? RAID 4 uses a dedicated parity disk while RAID 5 distributes parity data across all drives in the RAID set.  Continue Reading

• Hitachi replication: How do you do replication for HDS arrays?

  Hitachi replication: Find out how to do replication for HDS arrays, as well as which replication method is best suited for AIX servers.  Continue Reading

• Backup best practices: Is it best to use a dedicated backup server or a shared server that also runs

  Backup servers are responsible for scheduling thousands of backup jobs per day and committing thousands of associated backup details to the database. Here are some best practices for dealing with backup servers.  Continue Reading

• Dynamic code analysis vs. static analysis source code testing

  Managing vulnerabilities involves a wide array of security testing, including both dynamic and static source code analysis. Learn how the two differ, as well as how they are performed in this expert response.  Continue Reading

• RAID 5 recovery: What is the maximum number of physical drives in a RAID 5 configuration?

  Adding drives to a RAID 5 set increases your ROI and the likelihood of simultaneous drive failures, and lengthens RAID rebuild times. So what should be your physical drive limit?  Continue Reading

• Do all drives in a RAID 10 array need to be the same specification?

  We tell you the one requirement when matching drive specs in a RAID 10 array. But will mixing drives of various performance levels compromise your RAID level?  Continue Reading

• RAID 10 vs RAID 50: What is the best way to configure a storage array with 16 1 TB drives?

  Learn the characteristics of RAID 10 and RAID 50, as well as which RAID level is appropriate for your applications. I/O and protection needs contribute to your RAID choice.  Continue Reading

• Thin provisioning: Over-allocation, wide striping, space reclamation

  Learn how the three main advantages of thin provisioning -- over-allocation, wide striping and space reclamation -- can help you make the most of your storage.  Continue Reading

• SAN vs. DAS: Which is better in terms of performance and scalability?

  Is SAN or DAS better in terms of performance and scalability? Learn why the server configuration you want to support plays such a big role in your decision.  Continue Reading

• Virtual server backup: image-level backup and file-level backup

  Virtual server backup involves two types of backup: image-level backup and file-level backup. Learn the differences between them, and the limitations of file-level backup.  Continue Reading

• Using RAID 1 and RAID 5 in a virtual server environment

  We tell you the pros and cons of using RAID 1 and RAID 5 for your OS and applications in a virtual server environment. Data protection and recovery are factors to consider.  Continue Reading

• LUN masking or LUN zoning: Which one is a better fit for a SAN fabric?

  GlassHouse Technologies' Steve Pinder weighs the pros and cons of using LUN masking and LUN zoning in SAN fabrics, switches and HBA configurations.  Continue Reading

• Fibre Channel SAN zoning: Pros and cons of WWN zoning and port zoning

  Learn the difference between World Wide Name zoning (WWN zoning) and port zoning, as well as the pros and cons of each on a Fibre Channel storage-area network (Fibre Channel SAN).  Continue Reading

• Storage-area network (SAN) fabrics: Mesh versus core-edge topology

  When designing a storage-area network (SAN) fabric, it is important to examine both mesh and core-edge SAN topologies. Learn about the pros and cons of both topologies for designing SAN fabrics and which choice is best suited for small- and ...  Continue Reading

• How to calculate the optimum fan-out ratio on a storage-area network (SAN) array

  Learn how to calculate the optimum fan-out ratio –- number of hosts connected to a port -- for a SAN array hosted in your enterprise data storage infrastructure.  Continue Reading

• What are the main steps when configuring a storage-area network (SAN) switch?

  Learn how to perform a storage-area network (SAN) switch configuration by determining the required port speed and topology, and configuring zones so devices can communicate with each other.  Continue Reading

• What are some best practices for storing backup tapes offsite?

  Shipping tapes offsite? Learn the importance of recovery time objectives and recovery point objectives, inventory lists and migrating media to newer technology.  Continue Reading

• What type of data storage media is best for data with long retention requirements?

  Learn what types of data storage technologies, including SATA, MAID, virtual tape libraries (VTLs) and tape drives, are best suited for data with long retention requirements.  Continue Reading

• What causes slow data backups and how can you make your backup environment more efficient?

  GlassHouse UK consultant Hywel Matthews says slow data backups -- caused by either the size of the backup pipe or the flow of the backup data -- can be addressed with various backup agents, data deduplication products, and more.  Continue Reading

• Recovering from a two-drive failure in a RAID 10 configuration

  In a RAID 10 configuration with four drives, data can be recovered if two of the drives fail. But recovering the data depends on which drives in the RAID configuration fail.  Continue Reading

• How to choose the right RAID configuration for a new storage-area network (SAN)

  Before choosing a RAID configuration for a new storage-area network (SAN), you need to consider the performance requirements of your data and the number of disks needed for an effective implementation.  Continue Reading

• What makes a fabric port change to a loop port?

  If ports in your storage-area network switch are changing without updates, you need to examine the fabric device and loop device, and check to see if any drives may have been improperly connected.  Continue Reading

• RAID 10 vs. RAID 1: Mirrored drives matter

  While RAID 10 and RAID 1 are both mirroring technologies that utilise half the available drives for data, a crucial difference is the number of drives they can use in a RAID group.  Continue Reading

• RAID 10: How many disk drives should you use?

  The minimum number of drives required for RAID 10 is four. RAID 10 should not be confused with RAID 0+1, which involves creating two RAID 0 stripe sets and then mirroring them.  Continue Reading

• How do you defragment NAS?

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• Active-active array vs active-passive array: Storage arrays explained

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• What is a LUN and why do we need storage LUNs?

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• RAID 5 configuration: How to calculate disk space for data storage and parity storage

  Find out how to calculate the disk space available for data storage and how much disk space is utilised for parity storage in a RAID 5 configuration.  Continue Reading

• Can I use a PC server as a NAS device?

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• NAS Backup: What are my options?

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• RAID 1 vs RAID 5: What are the pros and cons?

  What are the pros and cons of the mirrored disk sets of RAID 1 and the parity disk protection of RAID 5?  Continue Reading

• Managing offsite backup tape storage: How far away should tapes be stored?

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• Agent-based and agentless replication - what are the pros and cons?

  Agent-based and agentless replication - what are the pros and cons?  Continue Reading

• What are the dangers of using Facebook, other social networking sites?

  Ken Munro discusses the dangers associated with allowing employees to access social networking sites such as Facebook, and explains how corporations can avoid these risks by monitoring the information placed in employee profiles and using email ...  Continue Reading

• What are the advantages and applications of FCoE?

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• Disk-based backup vs. tape

  Get advice on choosing disk versus tape for small businesses.  Continue Reading