raid
- Thread starter dd_viper
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- NAS / RAID Video
Good or Bad have no meaning at all, depends on what your point of view is.
- Dec 31, 2007
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RAID means "Redundant Array of Independant Disk" (originally joked as "Inexpensive" disk so they could use a different acronym for large expensive disk).
Level 0 isn't actually RAID because it's not redundant, but uses the same technology so it's called RAID anyway.
Level 0 is striping, all data is broken up into chunks and split between two drives. That gives you the bandwidth of 2 drives as opposed to 1 in order to speed up transfers.
Level 1 is mirroring, one drive is an exact copy of the other. It doesn't help performance, but offers 100% redundance in case 1 drive fails. Because one is a copy of the other, you only get the capacity of 1 drive (half the capacity of the 2 drives you're using).
Level 3 requires at least 3 drives because the third is used to store parity information uses to recover a drive without having all the data. The other drives sort of act like level 0, but you don't get a performance boost because the controller has a lot of calculations to do (it creats parity bits).
Level 5 is similar to level 3 but divides the drives into several chunks and distributes the parity to certain places on each drive, rather than putting it all on one drive. It's generally faster than level 3.
Level 10 (or 0+1) uses 4 drives, which consist of 2 level 0's. The second level 0 array is a copy of the first. It has all the advantages of Level 0 and 1, and the disadvantage that it still gives you only 1/2 your capacity.
Level 50 is a Level 5 array constructed of several Level 0 arrays. It's probably the fastest and has great redundancy, but requires you to have a lot of drives.
There are also some oddball types, but those are the main ones.
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
Level 0 isn't actually RAID because it's not redundant, but uses the same technology so it's called RAID anyway.
Level 0 is striping, all data is broken up into chunks and split between two drives. That gives you the bandwidth of 2 drives as opposed to 1 in order to speed up transfers.
Level 1 is mirroring, one drive is an exact copy of the other. It doesn't help performance, but offers 100% redundance in case 1 drive fails. Because one is a copy of the other, you only get the capacity of 1 drive (half the capacity of the 2 drives you're using).
Level 3 requires at least 3 drives because the third is used to store parity information uses to recover a drive without having all the data. The other drives sort of act like level 0, but you don't get a performance boost because the controller has a lot of calculations to do (it creats parity bits).
Level 5 is similar to level 3 but divides the drives into several chunks and distributes the parity to certain places on each drive, rather than putting it all on one drive. It's generally faster than level 3.
Level 10 (or 0+1) uses 4 drives, which consist of 2 level 0's. The second level 0 array is a copy of the first. It has all the advantages of Level 0 and 1, and the disadvantage that it still gives you only 1/2 your capacity.
Level 50 is a Level 5 array constructed of several Level 0 arrays. It's probably the fastest and has great redundancy, but requires you to have a lot of drives.
There are also some oddball types, but those are the main ones.
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
Ned_Flanders
Splendid
- Jan 30, 2004
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<A HREF="http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&p=61149#61149" target="_new">You complete Sh!t, look before you ask</A>
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Actually refering to "RAID" as "Redundant Arrays of Inexpensive Disks" was NOT a joke.
This was, indeed, the original wording of what RAID was. (As defined in a 1987 paper published at the University of California Berkeley by Patterson, Gibson, and Katz. The paper was titled "A Case for Redundant Arrays of Inexpensive Disks (RAID)".)
Inexpensive was important at the time, since hard drives often could cost tens of thousands of dollars. (One really cool thing though was that many of the IBM drives had Field Replaceable motors, read/write heads, bearings, etc..... BY TECHNICIAN's.)
Of course, like many things, someone else "claimed" to have invented the concept. A company call "Storage Computer Corporation" discoved in 2001 that it had filed a paper on that same concept and had actually patented that concept as well! Later they sued several manufacturers but in 2002 their patent was ruled invalid.
This was, indeed, the original wording of what RAID was. (As defined in a 1987 paper published at the University of California Berkeley by Patterson, Gibson, and Katz. The paper was titled "A Case for Redundant Arrays of Inexpensive Disks (RAID)".)
Inexpensive was important at the time, since hard drives often could cost tens of thousands of dollars. (One really cool thing though was that many of the IBM drives had Field Replaceable motors, read/write heads, bearings, etc..... BY TECHNICIAN's.)
Of course, like many things, someone else "claimed" to have invented the concept. A company call "Storage Computer Corporation" discoved in 2001 that it had filed a paper on that same concept and had actually patented that concept as well! Later they sued several manufacturers but in 2002 their patent was ruled invalid.
Sorry crashman, not quite correct.
It is a popuilar misconception Raid 0+1 is the same as raid 10 or 1+0.
For example say 10 Hard disk drives are to be used;
Raid 0+1 is 2 sets of five drives mirrored as compared to raid 1+0 or 10 as five sets of two drives mirrored.
the difference is somewhat complicated and is better described<A HREF="http://www.pcguide.com/ref/hdd/perf/raid/levels/multXY-c.html" target="_new"> here</A>.
- Dec 31, 2007
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Yes, I was sloppy, RAID 10 is a Level 1 array made up of two RAID 0 arrays. And RAID 0+1 is a RAID 0 array made up of two RAID 1 arrays. You still need a minimum of 4 disks, just to keep anyone else from being confused.<A HREF="http://adaptec-tic.adaptec.com/cgi-bin/adaptec_tic.cfg/php/enduser/std_adp.php?p_sid=HlPuEemh&p_lva=&p_faqid=3621&p_created=1017241779&p_sp=cF9zcmNoPTEmcF9ncmlkc29ydD0mcF9yb3dfY250PTE1NTImcF9zZWFyY2hfdGV4dD13aGF0IGlzIFJBSUQgMTAmcF9zZWFyY2hfdHlwZT0zJnBfcHJvZF9sdmwxPX5hbnl_JnBfcHJvZF9sdmwyPX5hbnl_JnBfY2F0X2x2bDE9fmFueX4mcF9wYWdlPTE*&p_li=" target="_new"> </A>
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
- Dec 31, 2007
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Nah, it's just in order, 0+1, 1+0 (10), depending on which array comes first.
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
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