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Home -> Community -> Mailing Lists -> Oracle-L -> RE: SAME, WAFL and RAID
Great
! Thanks for the info..
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Kirti
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<FONT face=Tahoma
size=2>-----Original Message-----From: Nick Wagner
[mailto:Nick.Wagner_at_quest.com]Sent: Tuesday, January 15, 2002 3:49
PMTo: Multiple recipients of list ORACLE-LSubject: RE:
SAME, WAFL and RAID
good question... RAID and WALF -- see below.
SAME... no idea...
RAID - (from <A
href="http://www.uni-mainz.de/~neuffer/scsi/what_is_raid.html"
target=_blank>http://www.uni-mainz.de/~neuffer/scsi/what_is_raid.html
) What does RAID stand for ? In
1987, Patterson, Gibson and Katz at the University of California Berkeley,
published a paper entitled "A Case for Redundant Arrays of Inexpensive Disks
(RAID)" . This paper described various types of disk arrays, referred to by the
acronym RAID. The basic idea of RAID was to combine multiple small, inexpensive
disk drives into an array of disk drives which yields performance exceeding that
of a Single Large Expensive Drive (SLED). Additionally, this array of drives
appears to the computer as a single logical storage unit or drive.
The Mean Time Between Failure (MTBF) of the array will be equal
to the MTBF of an individual drive, divided by the number of drives in the
array. Because of this, the MTBF of an array of drives would be too low for many
application requirements. However, disk arrays can be made fault-tolerant by
redundantly storing information in various ways.
Five types of array architectures, RAID-1 through RAID-5, were
defined by the Berkeley paper, each providing disk fault-tolerance and each
offering different trade-offs in features and performance. In addition to these
five redundant array architectures, it has become popular to refer to a
non-redundant array of disk drives as a RAID-0 array.
WAFL (from the NetApp website) The WAFL
(Write Anywhere File Layout) file system and the following features deliver
enterprise-class availability:
Consistency
points. Always a consistent file-system image on disk, even after unplanned
shutdowns. Virtually eliminates the need to run time-consuming file-system
checks.
Snapshot technology.
Snapshots are near-instantaneous, transparent, read-only, online copies of the
active file systems. Up to 31 Snapshots can be maintained for each data volume.
Users can quickly recover deleted or modified files without administrative
assistance or restore from tape backup. The Snapshot function requires minimal
disk space and causes no disruption of service. Snapshots can be backed up to
other media while users are modifying the active file system to minimize
business disruption.
SnapRestore software.
Allows any system to revert back to a specified data volume Snapshot for instant
file-system recovery. Terabytes can be recovered in minutes, rather
than hours, without going to tape. The software also greatly facilitates
scenario testing as well as providing disaster recovery and virus protection.
Easy, cost-effective clustering. Safeguards against hardware failures by automatic filer takeover. Gives users continuous access to data.
SnapMirror software. Provides remote mirroring at high speeds
over a LAN or WAN. The asynchronous mirroring can be used for disaster recovery,
replication, backup, or testing on a nonproduction system.
-----Original Message----- From:
Deshpande, Kirti [<A
href="mailto:kirti.deshpande_at_verizon.com">mailto:kirti.deshpande_at_verizon.com]
Sent: Tuesday, January 15, 2002 1:23 PM <FONT
size=2>To: Multiple recipients of list ORACLE-L Subject:
RE: SAME, WAFL and RAID
Good idea..
All I know about WAFL is the House where breakfast is served ;)
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