Thank you for purchasing through links and ads on this site.
OWC / MacSales.com...
diglloyd Deal Finder...
Buy other stuff at Amazon.com...
Upgrade the memory of your 2019 iMac up to 128GB
Handpicked deals...
$1799 $1399
SAVE $400

$719 $230
SAVE $489

$198 $138
SAVE $60

$695 $195
SAVE $500

$1997 $897
SAVE $1100

$1099 $999
SAVE $100

$348 $278
SAVE $70

$348 $278
SAVE $70

$3099 $2499
SAVE $600

$2099 $1799
SAVE $300

$275 $275
SAVE $0

$699 $499
SAVE $200

$1398 $1098
SAVE $300

$1699 $1299
SAVE $400

$2999 $2999
SAVE $0

$1699 $1443
SAVE $256

$2798 $2498
SAVE $300

$2399 $2249
SAVE $150

$3798 $1898
SAVE $1900

$2798 $2498
SAVE $300

$2497 $1997
SAVE $500

$2498 $1798
SAVE $700

$3297 $2197
SAVE $1100

$2798 $2498
SAVE $300

$2998 $2498
SAVE $500

$1398 $1198
SAVE $200

$898 $798
SAVE $100

$400 $250
SAVE $150

$1299 $939
SAVE $360

$4078 $4078
SAVE $0

$4499 $2999
SAVE $1500

$4999 $4599
SAVE $400

$2199 $1999
SAVE $200

$2799 $2349
SAVE $450

$3099 $2499
SAVE $600

$2001 $1298
SAVE $703

$2199 $1499
SAVE $700

$249 $149
SAVE $100

$2844 $2297
SAVE $547

$1199 $1099
SAVE $100

$2019 $1399
SAVE $620

$999 $949
SAVE $50

RAID Fault Tolerance : Keep a Cold Spare

Last updated 2014-06-08 - Send Feedback
Related: fault tolerance, RAID, storage

See the discussion of fault tolerance.

When using fault-tolerant RAID such as RAID-5 or RAID 1+0 or RAID-1, it is essential to have a cold spare on hand so that the failed drive can be replaced immediately.

A cold spare is a matching drive for the other drives in the RAID, set aside as a replacement to be used when needed. Some hardware RAID systems also support a hot spare (a drive that is already in the RAID, but not used until a failure occurs).

By keeping a cold spare on hand, the RAID can restore (“rebuild”) its fault-tolerant state, which can be a lengthy process (all day or longer). Without a cold spare, it might take some days to obtain a replacement before that process can begin, if a matching drive can be found at all (discontinued).

For example, the failure of one drive in a RAID-5 means that it reverts to a RAID-0: failure of another drive failure means total loss of the volume. It’s all a matter of odds, and perhaps the Murphy’s Law principle: when something bad happens, something worse might follow!. By starting the rebuild process ASAP, the risk of losing the volume is minimized.

The ideal cold spare is one already mounted in a spare drive carrier, and pre-tested and pre-initialized, ready for immediate use.

Spare hard drive mounted in drive sled for use as cold spare


View all handpicked deals...

Dell UltraSharp 27 U2717D 27" 16:9 InfinityEdge IPS Monitor
$719 $230
SAVE $489

diglloyd.com | Terms of Use | PRIVACY POLICY
Contact | About Lloyd Chambers | Consulting | Photo Tours
Mailing Lists | RSS Feeds | Twitter
Copyright © 2019 diglloyd Inc, all rights reserved.
Display info: __RETINA_INFO_STATUS__