Home > Ask the Storage Technology Experts > Storage Management Questions & Answers > RAID-5 configuration
Ask The Storage Expert: Questions & Answers
EMAIL THIS

RAID-5 configuration

Ashley D'Costa EXPERT RESPONSE FROM: Ashley D'Costa

Pose a Question
Other Storage Categories
Meet all Storage Experts
Become an Expert for this site


Digg This!    StumbleUpon Toolbar StumbleUpon    Bookmark with Delicious Del.icio.us   


>
QUESTION POSED ON: 25 April 2007
I have installed four hard disks of 146 GB using RAID-5 (auto configuration) on an HP server DL380. On the disk space, it shows a total of only three disks. Is the problem that the other one has been made a spare? Could you please clarify how RAID-5 utilizes the one that is not showing?


BROWSE BY TAG
SAN (storage area network),   SAN management,   Primary Storage or Storage Hardware,   RAID,   Storage Management,   Related information,   Disk Hardware FAQ,   Disk Storage,   Configuring RAID,   RAID,   VIEW ALL TAGS

Digg This!    StumbleUpon Toolbar StumbleUpon    Bookmark with Delicious Del.icio.us   



RELATED CONTENT
SAN management
Unilever maintains 5 PB Fibre Channel SAN storage performance with Virtual Instruments' NetWisdom
Storage Decisions Chicago 2009 Session Downloads
Storage Decisions Session Downloads: Managing Storage Networks Track (Chicago 2009)
Storage-area networks to become increasingly object based
Data storage management in virtual server environments
10 Gb Ethernet bodes well for iSCSI
Mellanox builds bridge to consolidation
Best storage Products of the Year 2008
Wide stripe before you dive into SSD
How your SAN will evolve
SAN management Research

RAID
Pivot3 and Seanodes increase performance, scalability of iSCSI storage products
Fujitsu adds DX60 and DX80 midrange disk arrays to Eternus line
Storage Decisions Chicago 2009 Session Downloads
MAID technology remains underutilized
The state of MAID in data centers
MAID product roundup
The evolution of RAID data protection
RAID changes its stripes, but not its value
Post-RAID products
Faster disk drive rebuilds: Hot Spots
RAID Research

Storage Management
Why RAID rebuilds obstruct data migration
Creating half a mirror out of 3 drives totaling 300 GB
Growing a RAID group by adding old drives
How to calculate available disk space on a RAID 5
Why does my EMC 45 TB drive yield only 41 TB of usable storage?
RAID 4 vs. RAID 5
External SATA RAID array vs. system replacement
Separate or combine tiers in SAN?
Stephen Foskett: Blogs and more
How much hard disk drive space should I actually use?

RELATED GLOSSARY TERMS
Terms from Whatis.com − the technology online dictionary
Fast Guide to Storage Technologies  (WhatIs.com)
fat provisioning  (SearchStorage.com)
oversubscription  (SearchStorage.com)
RAID  (SearchStorage.com)
storage area management  (SearchStorage.com)
storage area network  (SearchStorage.com)
thin provisioning  (SearchStorage.com)
unified storage  (SearchStorage.com)
virtual provisioning  (SearchStorage.com)
zoned-bit recording  (SearchStorage.com)

RELATED RESOURCES
2020software.com, trial software downloads for accounting software, ERP software, CRM software and business software systems
Search Bitpipe.com for the latest white papers and business webcasts
Whatis.com, the online computer dictionary


RAID-5 is a protection scheme where both data and parity information are striped across three or more drives. The parity information, which is used to rebuild data during a single drive failure, is spread across all the drives in the array in a stripe just like the data itself is. The total space consumed by the parity information is equivalent to an entire drive. So, in your four hard disk configuration, the fourth disk is not a spare but rather is the "parity drive."

However, be aware that this is not an actual physical drive but rather the space that would have been taken up by a physical drive if the parity information were not spread across all four drives. In short, in your RAID-5 configuration, all four drives are fully active, but from the operating system's perspective, total capacity is that of three drives.




Search and Browse the Expert Answer Center
Search and browse more than 25,000 question and answer pairs from more than 250 TechTarget industry experts.
Browse our Expert Advice



Search for Data Management Tools
TechTarget Storage Media
Storage Magazine View this month\\'s issue and subscribe today.
Storage Decisions Apply online for free conference admission.
SearchStorage.com
HomeNewsMagazineTopicsLearningMultimediaWhite PapersBlogsEventsAbout Us

About Us  |  Contact Us  |  For Advertisers  |  For Business Partners  |  Site Index  |  RSS
TechTarget provides technology professionals with the information they need to perform their jobs - from developing strategy, to making cost-effective purchase decisions and managing their organizations' technology projects - with its network of technology-specific websites, events and online magazines.

TechTarget Corporate Web Site  |  Media Kits  |  Site Map




All Rights Reserved, Copyright 2000 - 2009, TechTarget | Read our Privacy Policy
  TechTarget - The IT Media ROI Experts