RAID Technology

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Time
12 hours 9 minutes
Difficulty
Beginner
CEU/CPE
12
Video Transcription
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>> This is lesson 5.5 and
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we're going to talk about RAID technology.
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An overview of RAID 0,
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1, 5, and RAID 10.
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Let's go ahead and get started.
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Let's have a brief RAID technology overview.
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Then we're going to talk about
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>> the RAID levels in detail.
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>> We're going to finish off talking about
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the hot swappable drives.
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Let's go ahead and get started.
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RAID technology.
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RAID redundant array of inexpensive disks or drives,
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or redundant array of independent disks,
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however you want to call it.
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It is a data storage virtualization technology
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that combines multiple
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physical disk drives components into
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one or more logical units
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for the purpose of data redundancy,
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performance improvement or both.
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RAID bot works by placing
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data on multiple disk and allowing
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input-output operations to overlap
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in a balanced way, improving performance.
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Because the use of multiple disc increases
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the mean time between failures or MTBF,
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storing data redundantly also increases fault tolerance.
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RAID arrays appear to
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the operating system as a single local hard disk.
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RAID employs the techniques of
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disk mirroring or disk striping.
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Mirroring copies identical data onto more than one drive.
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Striping partitions each drive storage spares into
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units ranging from a sector of
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512 bytes to several megabytes.
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The stripes of all disk are
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interleaved and addressed in order.
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Now RAID technology is one of
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my favorite topics to talk about and discuss and use.
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I've used RAID for
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many years in many different situations,
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whether is for desktop as well as server applications.
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Believe me, RAID is one of
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those technologies that once you learn
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a little bit about it and start using it,
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when you look or have
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an application that needs data to be saved,
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or you can not do without that data,
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you want to use RAID,
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it will save you.
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It will save you a lot.
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First, before we jump into the RAID levels,
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let's talk about hardware versus software RAID.
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There's two kinds out there,
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and both have its advantages
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and some have its disadvantages.
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Hardware RAID versus software RAID.
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In hardware RAID, the drives
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connect to a RAID controller card that's
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inserted in the first PCI-e slot on the motherboard.
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There's PCI-e, again
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that critical component of a lot of system.
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This works the same for
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larger service as well as desktop computers.
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Many external RAID drive enclosers
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have RAID controller cards built right into them.
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Those NAS devices or
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those separate RAID controller storage devices
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that's outside of the server or the PC.
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They have a controller card built right into them.
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Hardware RAID works through
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a RAID controller card built right into the server.
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That's what controls the RAID
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or give you the RAID functionalities.
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Depending on that type of card and the vendor,
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would be the levels of RAID that you
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can manipulate the drives with.
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I've seen some RAID cards that has pretty much
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all the RAID levels or limited to just certain ones.
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A lot of times they will have
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their own certain software interface where you
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can connect those RAIDs or configure those RAIDs.
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Pros to hardware RAID,
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it's a standard across a many operating systems.
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Meaning if you had a server with a RAID controller card,
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you could install many different operating systems,
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whether it be a Windows-based or Linux-based.
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Those RAID hardware cards,
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will work with those many different operating systems.
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One of the cons about a RAID controller card,
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it tends to be a little bit more expensive.
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You're talking more and more hardware,
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high-cost hardware.
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Those are the pros and cons of
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a hardware RAID application.
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Software RAID, storage drives are connected
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directly to the computer or
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server without a RAID controller.
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RAID configuration is managed by utility software in
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the operating system which is
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referred to as a software RAID setup.
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Numerous operating systems support RAID configuration,
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including those from Apple, Microsoft,
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various Linux flavors, as well as OpenBSD,
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FreeBSD, NetBSD, and Solaris Unix.
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Pros and cons.
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You don't have a high cost as far as
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with a dedicated RAID controller card,
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the operating system can control that RAID.
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Cons about software RAID
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is because you don't have that controller card,
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you have a lower price point.
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But however, you may be limited
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to the flavors of RAID that you can use in that system.
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The software may only support one,
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and zero RAID or RAID 1.
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It may not support the entire line
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of levels that you may be needing.
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It's also operating system specific.
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Say for instance that's a Windows PC
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that you're using that software RAID on,
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you may not be able to get the same
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functionality out of Apple
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or Linux because it's software-based.
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Those are the pros and cons.
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Depending on your application,
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you'd have to choose what's
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best for you and your application.
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Let's go ahead and step through the RAID levels
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here and talk about these for a little bit.
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RAID 0 known as striped.
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This configuration is the least redundant.
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This configuration has some striping
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but no redundancy of data.
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It offers the best performance,
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but no fault tolerance.
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If one drive fails, everything is lost.
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One of the benefits here in RAID 0 is that it's fast.
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The performance here is a very good performance.
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But you would only want to use
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this situation if your system is doing
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frequent backups of the data somewhere else
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off of the disk drives here.
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Again, it writes to both disc.
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Really fast situation but if one disk fails,
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you lose that data.
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RAID 1, also known as disk mirroring.
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This configuration consist of
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at least two drives that duplicate the storage of data.
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There is no striping.
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RAID performance is improved since
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either disk can be read at the same time.
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RAID performance is the same as
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for a single disk storage.
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If one drives fail,
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an identical copy remains on the surviving drive,
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and this is probably one of the more, I will say,
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the go-to RAIDs is RAID 1 because again,
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you can use it with two drives.
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One disk fails, you have your data
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still there on the other drive.
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Bare minimum, basic RAID at its best, right here.
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RAID 5, this level is based
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on block-level striping with parity.
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If you remember what parody is,
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it is error code detection back from the memory lessons.
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The parity information is striped across each drive,
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allowing the array to function,
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even if one drive were to fail.
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The array's architecture allows read and
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write operations to span multiple drives.
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This results in performance that is
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usually better than that of a single drive,
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but not as high as that of a RAID 0 array.
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RAID 5 requires at least three disc,
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but is often recommended to use
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at least five disk for performance reasons,
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one of the most secure ways to set up disk.
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Now a con to RAID 5 is,
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it's probably one of the most expensive too,
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because of the required five disk.
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That's a little generally expensive cost
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depending on the application,
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[NOISE] so that's RAID 5.
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Now let's look at RAID 10 or RAID 1 plus 0,
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combining RAID 1 and RAID 0,
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this level is often referred to as RAID 10,
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which offers higher performance than RAID 1,
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but at a much higher cost.
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In RAID 1 plus 0,
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the data is mirrored and the mirrors are striped.
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You have mirroring and
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striping going on in RAID 1 plus 0.
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I've used this one in a lot of
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different applications because you
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get the best of both worlds,
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you get mirroring and striping.
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Let's talk about hot swappable drives.
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A feature of RAID arrays and system is being able
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to hot swap drives or the system is hot swappable.
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What this means is that any event of
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a hardware failure and a drive is no longer functioning,
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you can replace that drive while the system is running,
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maintaining 100 percent up time.
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Drives are able to be inserted into the chassis and
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removed without any downtime whatsoever.
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So if you have a high critical environment
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and your system is running
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operations that cannot be cut down and you do
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have RAID and you have your system set up that way,
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if a drive fails with hot swap or hot swappable drives,
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you can replace that drive
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without taking the system down,
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thus causing your company or
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your customers' downtime to do maintenance.
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You can hot swap them right there on
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the spot while the machine is running.
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This is a very beneficial and valuable feature
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of RAID arrays.
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We have talked about
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RAID technology overview and we've stepped through
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the RAID levels that you would need to know for
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the CompTia A plus RAID 0,
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RAID 1, RAID 5,
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and RAID 1 plus 0 or RAID 10.
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Also, we talked about hot
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swappable and that particular feature.
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That is it for this lesson,
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we will see you in the next lesson.
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