scsi or what we refer to in the industry as scuzzy is the small computer systems interface this is a standard interface that can be used to connect to storage devices scanners printers and other devices on your network this was originally designed so that you could have many devices connected to one single interface on your computer by daisy chaining multiple devices together and many of the scuzzy standards support up to 16 devices in one of those single scuzzy chains this is a standard that's been around for quite some time so you'll find a number of different scuzzy standards with different types of interfaces and different types of cables for each one of these standards one of the newest standards is iscsi or scuzzy over ip and certainly you'll find a lot of scuzzy implementation in virtual networks and if you look at some of the other connectivity that we use for storage devices such as pata which is a parallel connectivity and sata which is serial connectivity scuzzy can support both parallel and serial connectivity depending on which type of format you're using for that scuzzy connection before we had the sata standard or was able to use usb to be able to connect our peripherals we used scuzzy scuzzy was used to connect our scanners and our cd-rom drives and our tape backup systems and we add scuzzy connectivity inside of our computers and external interfaces that you could also use and as i mentioned earlier you can daisy chain these devices so a single interface on your computer might support eight different scuzzy devices on a narrow bus or up to 16 if you're using a wide bus version of scuzzy one of the benefits of scuzzy and the protocols that are used to communicate over this scuzzy connection is that it is a very intelligent form of connectivity you simply provide the basic connectivity and scuzzy takes care of identifying what devices are in that chain and how to access those devices over the scuzzy connection and although scuzzy doesn't have the popularity that it had in the past you may still find systems that have scuzzy drives or other types of scuzzy connectivity and scuzzy as a standard is one that's used extensively on our virtual systems here's a somewhat dated motherboard that does have a scuzzy connector on it this motherboard also has a floppy drive connector and an integrated drive electronics or ide interface today we refer these interfaces as pata interfaces on the left side is the scuzzy interface this is an ultra 3 interface that has 68 pins on this connector if we turn the motherboard on its side we can see exactly the pins that are used for this particular cable the cable itself is a 68 pin cable you can see where it plugs into the motherboard and you can see along the length of this ribbon cable are connections that you can use to attach other scuzzy devices that 68 pin connector that we see on the motherboard is just one of many types of scuzzy connections you can see that they have changed quite a bit through the years and you may find that one or more of these connectors is being used by scuzzy devices that might be in your data center when you have a single interface on your computer that you're connecting multiple devices to you need some way to be able to differentiate between all of these separate devices you're connecting to the same cable in scuzzy we're able to accomplish this by using a scuzzy id number so every device you would connect to that particular scuzzy cable would all have a separate id number associated with it so your computer might be a scuzzy id 0 you might be connecting to your computer a hard drive on that cable that can be assigned an id number of two and you might have another device on that cable such as a cd-rom and you would assign a separate scuzzy id to that device for example scuzzy id3 if you think about connectivity to a drive array it's a single chassis with many different drives inside of it because of this scuzzy has a method not only to identify the chassis of that drive array through a scuzzy id but we can identify individual drives by a logical unit or l-u-n that logical unit allows you to reference a single drive within a much larger scuzzy id device it's also very common on this cable that at the end of the cable you place a scuzzy terminator the scuzzy terminator allows you to have multiple devices on this wire and still be able to communicate across all of those devices simultaneously one of the more recent standards for scuzzy is a serial attached scuzzy or sas these devices are much simplified over the older scuzzy configurations that require you to manually set a scuzzy id and to always have a terminator on the connection with these newer sas devices you don't have to worry about setting jumpers for scuzzy ids you don't have to install any terminators or make any additional settings to be able to use those serial attached scuzzy devices here's the back of an external scuzzy storage device you see we have a spot for power looks like there's a fan inside of this device or some type of cooling and here are the scuzzy interfaces one that is a scuzzy out and one that is a scuzzy in this is how you would be able to daisy chain this particular device along with other scuzzy devices on the same cable this scuzzy device has been assigned a scuzzy id of six and you can see there are buttons on this device that allow you to modify the scuzzy id to prevent any conflicts on that same cable so if you look inside of a computer that has a scuzzy controller and multiple scuzzy hard drives you'll probably see the scuzzy controller set to a scuzzy id of zero and then there's probably a cable from that device that goes to the first hard drive and that drive is daisy chained to in this case a second hard drive and then at the end of that cable is a scuzzy terminator this is what the scuzzy terminator looks like that is connected to the end of that scuzzy cable so if you look inside one of these computers with scuzzy interfaces you may find a cable that looks something like this you can see that it plugs into the motherboard it's got a long set of cables here's one connector for a storage device another connection a third a fourth and then finally a terminator at the end of this cable so inside of the computer we would use a cable like that to connect to the motherboard and then one of those other connectors would connect to the scuzzy drives that are inside of our system here's a view of this scuzzy connection outside of a computer case you can see the motherboard is on the top with that scuzzy connector and that single ribbon cable wraps around and one of the interfaces on that ribbon cable connects to a storage drive you can see there are multiple interfaces on this cable so we can continue to add storage drives as long as we have connectors on this cable in our next video we'll talk about how we moved from the pata or parallel communication to sata or serial communication and scusi has had a very similar evolution one of the more recent standards for scuzzy is the serial attached scuzzy where we went from parallel communication to a serial communication this not only increased the total throughput that we could have in our systems but it greatly simplified the implementation in our computers because this is a point-to-point connection between the motherboard and the drive we no longer have these cables with multiple interfaces or devices with multiple scuzzy interfaces because there's no more daisy chains we also remove the need to have a terminator because the only thing on the serial attached scuzzy connection is the controller on one side and the hard drive or storage device on the other this gives us the control and management of a well-established scuzzy set of protocols but it also provides us with the speeds we need for our most modern storage devices here's a serial attached scuzzy drive you can see it looks very similar to a sata drive but the connectors on the back are slightly different and they do require a different set of connectors an example of this is this very large connector that is a high density internal sas connector that you would use inside of your computer and of course there are also serial attached scuzzy arrays so that you can connect many different serial attached scuzzy drives into this single chassis you