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A few qns on sata & scsi Hardrives. Please Help!

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  • Hard Drives
  • SATA
  • SCSI
  • Storage
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January 11, 2007 5:23:16 AM

qn1) I heard that HDs NEVER ever run above 150mbps and SATAII with a maximum bandwidth of 300mbps is useless.. my qn is, is it true? if it's not, then what is the highest a SATA II can reach?

qn2) do SATA I & SATA II use the same cables?

qn3) in general are SCSI drives faster than SATA II (related to qn1, as it it cant hit 300mbps ever, this qn is actually SCSI vs SATA I)

qn4) say a SCSI drive is rated 320mbps, does it REAlly run at that spd thru out? how about the 160mbps SCSI drives, do they also sustain at that spd?

qn5) I saw this clerance sale and the SEAGATE CHEETAH 36GB SCSI U160 10K RPM HDD was on sale really really cheap, so this last qn is direct. IS this SEAGATE CHEETAH or a Seagate 7200.10 faster(in overall performance, in particular data transfer & gaming. xp load isn't a issue for me)

More about : qns sata scsi hardrives

January 11, 2007 8:17:53 AM

help................
January 11, 2007 9:53:43 AM

Quote:
qn1) I heard that HDs NEVER ever run above 150mbps and SATAII with a maximum bandwidth of 300mbps is useless.. my qn is, is it true? if it's not, then what is the highest a SATA II can reach?

qn2) do SATA I & SATA II use the same cables?

qn3) in general are SCSI drives faster than SATA II (related to qn1, as it it cant hit 300mbps ever, this qn is actually SCSI vs SATA I)

qn4) say a SCSI drive is rated 320mbps, does it REAlly run at that spd thru out? how about the 160mbps SCSI drives, do they also sustain at that spd?

qn5) I saw this clerance sale and the SEAGATE CHEETAH 36GB SCSI U160 10K RPM HDD was on sale really really cheap, so this last qn is direct. IS this SEAGATE CHEETAH or a Seagate 7200.10 faster(in overall performance, in particular data transfer & gaming. xp load isn't a issue for me)


1.) This is true, SATA bandwidth, generation "I" or "II" is more than enough for any hdd as the fastest drives would be raptors.

2.)SATA is SATA... the differences in the two "generations" is just a few features and the frequency of the bus.

3.) YES! SCSI is almost always faster than SATA. Although for desktop use they're not quite useful since they're designed for like server workloads.

4.) When they says U320 or U160 SCSI they're talking about the bandwidth of the bus... not the hdds performance. What that means is that 320Mb/s is the max transfer rate of all the hdds in that chain.

5.) That IS a Seagate Cheetah, and it does run on a SCSI interface so unless you have a built-in SCSI controller on your mobo you're not going to be able to use these drives unless you buy a controller card.

Also... what is your reason for getting a SCSI drive? What will you be using it for?
Related resources
January 11, 2007 10:36:18 AM

THERE IS NO SUCH THING AS SATA II!

Now that's out of the way...

1) Sata 300Mb/s has a number of other enhancements over Sata 150Mb/s

2) Yes, they do.

3) In raw speed, yes, in latency, yes, in terms of "for general desktop use", no.

4) No. No.

5) It will be faster for data transfer and most likely slower for gaming.
January 11, 2007 11:41:05 AM

Quote:
Also... what is your reason for getting a SCSI drive? What will you be using it for?


last part of the 1st post. :wink:

thanks for the reply guys, but could u explain more on qn1, what exactly are the "other enhancements" of sataII over sataI.. and does it mean that all newer hds on the sataII interface are actually never ever at the speed of 300? and in fact lower than 150?
January 11, 2007 11:57:56 AM

Here we go. A little info about computers, hard drives, and what makes a computer fast or slow, etc...

A computer is made up of electronic parts. The speed of these electronics is in the nano-seconds, etc... the only mechanical device on your computer is the hard drive. It is the only device rated in mili-seconds. Therefore it stands that a hard drive is a major bottleneck in your computer. That is why servers use SCSI, Fibre channel, solid state hard drives, etc... To get a fast computer you need a fast hard drive.

This is why I laugh every time somebody asks me what kind of computer I own. I say its an Opteron 162 or whatever running on an Abit AB9 Quad GT or something like that. It's homebrew. The first response I usually hear is huh??? Is it 3GHz or what? I reply 1.8GHz or so. They say I have an HP from Staples that is a Pentium 4 3.2 GHz and they think their system is twice as good. Bull crap. Everyone rates computers quality in terms of CPU speed and I see way too many shops selling multi hundred dollar upgrades to the computer CPU for their packages instead of offering upgrades to hard drive, RAM, graphics cards for the same money and keeping a stock CPU. These people don't realize that you need a $500 graphics card to play games to the level they desire. And they don't realize that you need tons of RAM (to a cetian limit) and a good hard drive.

I remember in the past when 5400RPM was the thing. Adding a 7200RPM made a world of difference. I'd go from 20 seconds boot up time to 10 seconds. And SCSI made a world of difference too. Your hard drive is pumping pretty much 100% of the time while your computing and the faster your drive, the faster your system.

Now the hard drive is mechanical and slow remember. It can never keep up with the full speeds of SATA 1 or SATA II. Those are just interfaces, those are the speed capabilities of those interfaces, if you had devices that could work that fast. SATA is not just for hard drives, you can plug anything to SATA just like USB. Its just that nothing is made besides hard drives and soon DVD drives, so everyone assumes that the speed of SATA is the speed of your hard drive.

The speed of a hard drive comes mostly from its rotational speeds and access times. You can get the specs of access time in mili seconds and the rotational speeds in RPM. IDE-133 was fast enough for all current hard drives as they are only mechanically fast enough to run at around 100-133 MB/sec or so. This is why the Raptor is still faster than all curretn SATA II drives even though the Raptor is only SATA 1. The raptor is 10,000 RPM and has better access times. SCSI works in the same principle by have high RPM and very fast access times.

A way of thinking of this is by comparing it to mice. Is a USB mouse faster then a PS2 mouse? USB is faster than PS2 so the mouse has to be faster right? No, its the same mouse with a better interface. Same as hard drives, same drive mechanically, better interface. Hot swapable, better cables, no jumpers, same speed. As hard drives get faster SATA will be able to support these advanced speeds.

With 7200RPM and faster access times, you won't notice much difference between a SCSI drive or raptor drive and a normal SATA drive. I think you'd be better off going with SATAII and higher capacity 320GB+ drives. Capacity is worth more than speed for most people.

Windows operates off the C:\ drive. So while computing and using windows your hard drive needs to seek through the C:\ drive most of the time. That's why its good to make a seperate 20-30GB partition just for windows. Keep all your installs and data seperate from the C:\ and it will speed up your computer. You hard drive doesn't need to scan through all your 80GB of MP3s just to use windows. I've seen too many people with only a 200GB C:\ drive on their HP or DELL and they have 150GB of videos and music all over the place. First of all they have no clue where all their stuff is, they loose all their data everytime they fprmat C:\ and their computer is slow as hell since they hard drive needs to scan through 200GB of crap.

So to speed up your computer partition and use your drive properly. If you need extra speed get a RAPTOR drive just for windows. a 36GB is fine. if you need even more speed get those Seagate 15k RPM drives if they still exist. But your going to pay a lot for the drive nad the required controller.

So don't worry about SATA 1 vs SATA 2. Look at specs and access times for hard drives and benchmarks. The interface means nothing. A raptor SATA 1 is faster than a 7200RPM SATA 2. SCSI is still king although regular SATA drives are approaching it.

In my honest opinion, a couple of SATA II 320GB drives set up as a RAID and partitioned properly will provide good enough performance for most people, with the capacity we desire, at the lowest possible price.

Raptors and SCSI are reserved for servers where all the users have network storage, and for gamers and overclockers who demand top benchmarks just for the fun of it.
January 11, 2007 12:11:08 PM

wow thats a lot of words.. but i read every bit of it. thanks man!

anyway, so, now i know it's all just interface and typical HDs will never hit 300 of the sataII how about sataI?? will it hit 150?

oh and according to mkaibear above, he said that sata II has a few "other enhancements" as compared to sataI besides the interface speed. what are these "enhancements"?
January 11, 2007 12:37:56 PM

<begin wikipedia quote>

Soon after SATA's introduction, enhancements were made to the standard. A 3 Gbit/s signalling rate was added to the PHY layer, offering up to twice the data throughput. Like SATA 1.5 Gbit/s, SATA 3.0 Gbit/s uses 8B/10B encoding, resulting in a maximum data transfer rate of 2.4 Gbit/s or 300 MB/s for the wire. However, hard drives cannot supply data nearly at these speeds, so the actual speed depends on the hard disk.

To ensure seamless backward compatibility between SATA 1.5 Gbit/s controllers and SATA 3.0 Gbit/s devices, the latter devices are required to support the original 1.5 Gbit/s rate. In practice, some older SATA controllers do not support SATA speed negotiation, and require that SATA 3.0 Gbit/s peripherals be manually hardlimited to 1.5 Gbit/s with the use of a jumper. [1] Chipsets which exhibit this problem include the VIA VT8237 and VT8237R south bridges, and the VIA VT6420 and VT6421L standalone SATA controllers. [2] SiS's 760 and 964 chipsets also initially exhibited this problem, though it can be rectified with an updated SATA controller ROM. [citation needed]

The 3.0 Gbit/s specification has been very widely referred to as “Serial ATA II” (“SATA II”), contrary to the wishes of the Serial ATA standards organization that authored it. The official website notes that SATA II was in fact that organization's name at the time, the SATA 3.0 Gbit/s specification being only one of many that the former SATA II defined, and suggests that “SATA 3.0 Gbit/s” be used instead. (The Serial ATA standards organization has since changed names, and is now “The Serial ATA International Organization”, abbreviated SATA-IO.)

SATA 3.0 Gbit/s is sometimes also referred to as SATA 3.0 or SATA/300, continuing the line of ATA/100, ATA/133 and SATA/150.

<end wikipedia quote>
January 11, 2007 1:58:33 PM

Quote:

Windows operates off the C:\ drive. So while computing and using windows your hard drive needs to seek through the C:\ drive most of the time. That's why its good to make a seperate 20-30GB partition just for windows. Keep all your installs and data seperate from the C:\ and it will speed up your computer.


I will open this for discussion. I agree with having a separate partition(s) for data. I differ on an OS and Installs (Programs etc I assume) partition. I used to think this and have nearly all my programs on drive D:\ except for a few that didn't give me the option and one or two I knew were accessed on start up. This was on a 98se machine, and the reason was mainly to simpllify degramentation of the HD's and reduce the Scandisk time when a bad BSOD occured. I applied the same principle to an XP install.

The issue was load times were slow and some progam loads were slow. I am assuming the reason was because it was bouncing between the C and D drives, ie programs dump alot of files into windows directories. I swear some things also referenced the D drive even though I controlled the startup and there shouldn't have been anything accessed on D.

I changed my XP install to a larger C partition to include room for many programs etc. Load times were noticabley faster than having then on a D drive.

As I said its open for discussion. I only have a sample point of 1.
January 11, 2007 2:31:25 PM

My experience is similiar to pkquat's. I have created seperate partitions on the same drive to help in managing files. It does not result in a performance increase. With all the data that is being accessed on the same physical drive the disk is forced to seek across the platter between the two partitions. This is not much different than having your data in one partition. In fact if you know what applications are being used frequently the disk can be optimized to reduce the seek times if all the data is on one partition.

To get a performance increase you need a seperate physical drive (different disk spindle) that can keep the disk heads closer to the needed data (windows and application / data) and the disk read ahead cache can be more effectively used in retrieving data.

Comments?
January 11, 2007 4:43:22 PM

I would still recommend having a partition or two for plain data files such as downloads, documents, pictures, video, MP3's, etc. A setup like this also makes backing up dritical vs generic data easier.
January 11, 2007 7:24:37 PM

Anyone know how "vintage" ie year 2000, SCSI drives and adaptec controller would compare to todays SATA drives.

I recently acquired two external drives and an adaptec controller. The drives are SEAGATES, but I don't recall the model numbers. I think they are 7.5GB drives and do spin at 10k, but that seems high for that era.

If I remember correctly most 7200 SATA drives can still only sustain about 80MBps with some approaching 100MBps. I vaguely remember that these drives in raid 0 were U160 which I think means ~80MBps each max.

I thought about using them for the OS etc in Raid 0, but I might be just as fast with SATA Raid 0? Ebay them? Any idea for uses?
January 12, 2007 11:09:09 AM

Actually you guys are probably correct. A larger c:\ drive with your installs probably makes sense. After all when you format c:\ you still need to reformat d:\ and reinstall everything. Gotta reinstall all programs with windows to get all the registry changes, shortcuts, etc.... The only way around this would be to have a seperate drive for your programs. I guess a 36gb Raptor or 74gb would be great for windows and programs.

But what I was mainly getting at is people who have over 80gb of mp3s, pictures, and movies scattered all over the place. My received files, my pictures, my music, in their limewire directories, in their torrent directories, on the desktop, in random custom c:\ folders, etc.... Mixed up all over the place and they don't even know where half their stuff is. Then they have so much spyware that they can't access their windows anymore and it's impossible to back their stuff up. If all data was on d:\ then you could just format c:\ and be on your way.

I was in the habit of putting installs on d:\ and data on e:\ and f:\ because I liked the idea of just going into d:\ and I could see all the programs I have installed. But on my next format I may switch to a single c:\ for windows and programs. Data has gotta be the seperate partition and is what should be stressed.

As far as Harddrives yes the throughput is physically somewhere's around the 100mb/sec rate in the real world which means ATA_100 and ATA-133 are fast enough even for todays drives. As far as these enhancements you are talking about the main one that SATA II supported is hot pluggable drives which was supposed to be supported by SATA I. AS far as I've seen all new boards with SATA II are speced as supporting hot swappable hard drives. I am not familiar with this but does it mean that a hard drive could be plugged into a booted motherboard and windows will detect it, much like USB? This is a great fdeature for tech's. Just plug a hard drive into a booted PC on the external port and back it up or low level format and do your diagnostics. Could an experienced person please elaborate on the hot swapable feature in SATA II.

That is the only feature I am aware of with SATA II aside from the faster theoretical limits assuming hard drives where fast enough. I think I also remember something about longer cable spans? Not sure though, just something in the back of my ind I think I read once. This is nice since the current standard is I think 18" max which sux for full towers. hard to find longer cables except specialty online stores.

I also checked and Seagate does still make the Cheetah 15k drives. Those are some of the fastest SCSI drives I know of on the market. The 34GB version isn't too bad either comming in around $200 which would be great for windows and installs. I also realized that the capacities of the Raptor match those of SCSI drives at 34,74GB etc... those odd numbers. I'm thinking the Raptor is just a SCSI drive with a SATA controller in it. Still if you want exotic the Seagate Cheetah 15k is the way to go. Raptor is for kids with money.
January 12, 2007 12:10:42 PM

You don't to reformat d:\ if you do a reinstall or clean install on c:
You do however have to reinstall any apps you were using etc so that's why it's always a good point to install any apps to the same partition as windows.
What I do is a clean install to c:\ (100GB approx). Install all the necessary apps I'd use such as Office/Video Drivers/Games etc.
Then I repoint my Docs folder to D:\My Documents which is either on another partition or another drive (different on each system).
This allows to to reinstall whenever I want without losing anything.
Once I've finished installing all I need including games I create a backup image with ghost 10 and store it on another drive.
Voila..so if i need to start afresh again in a few months my system is completely restored within 20mins and running as good as new. It's a lot handier than completely installing everything again.
January 12, 2007 12:49:02 PM

Ghosting an image and redirecting your my documents works...but I'm too lazy to do all that. I use the opportunity of a format to download all the latest versions of my apps and drivers without having to uninstall older versions from a drive image.
January 12, 2007 1:49:35 PM

i don't really understand. how do u repoint ur doc folder?
January 13, 2007 7:34:16 AM

You can use TweakUI to redirect your folders
January 13, 2007 2:40:24 PM

and from there on; say when u want to download something online, the box that pops out will show ur document folder on another partition or hd instead of the one where xp is installed?

right?
January 13, 2007 2:45:15 PM

Yup it will work just like as if it was on the C:\
January 13, 2007 5:10:46 PM

wow okie.. so where do i download that software?
January 13, 2007 5:25:51 PM

TweakUI

There'll be a section called "special folders", select your my documents and change it to the proper drive, then direct the my music and my pictures etc. in the new my documents folder. Any questions feel free to pm me
January 14, 2007 1:51:55 AM

thanks pal
January 15, 2007 7:10:02 AM

You don't even need TweakUI to move your "My Documents" folder. Start up Windows Explorer, right-click on "My Documents", select "Properties". Go to the "Target" tab (should be automatically selected), and you can put in the new target for your "My Documents" folder - eg mine is set to D:\Documents at home, and C:\Documents at work.
January 15, 2007 9:42:33 AM

Hi, I just wanted to tell you about my experiences with hot-plugging SATA.

First I'll tell you what I know:
* When SATA came out, I heard it was supposed to support hot-plugging, but PC User Mag in Australia recommended not doing so, especially with your system hard disk. 8O
* When SATA2 came out, I again heard of them touting hot-plugging as a newly introduced feature ... go figure. :?

I have a SATA 1 (one) mainboard:
* In the past, I had my system drive (with Windows) on an IDE drive, and I was able to freely hot-plug my SATA1 drive. When I plugged it in, there was a few seconds delay and then it appeared in "My Computer". When I unplugged it, it simply disappeared from "My Computer". :) 
* Now I have my system on the SATA1 disk, so I'm not even going to try hot-unplugging it!!! However, I added a second SATA2 disk (I left on a jumper to limit it to SATA1 speed just in case) ... and I can freely hot-plug or hot-unplug this device with no problems. :D 
* In both cases - there's no USB sound, the drive just appears in "My computer" when you plug it in, and disappears when you unplug it. Simple 8)

I guess, technically, the feature would be even better supported on a true SATA2 system. I believe I may have heard that SATA2 has more advanced error checking...

...and it's [SATA2, that is] *supposed* to have Native Command Queueing as a default feature (some SATA1 drives have NCQ, but it's not mandatory for the SATA1 standard). Native Command Queueing I think better re-orders data requests by sequencing multiple requests for data so the drive can retrieve them with one sweep of the heads over the platter, rather than going back and forth getting data from here and there to service requests in their original order ... I think supposedly this improves overall drive speed as well reducing mechanical wear on the heads. But I'm no expert ...
a b G Storage
January 15, 2007 11:16:50 AM

Not to over simplify too much, but basically here is the deal-

SATA I and II have to deal with the interface, or connection to the drive.
Actually in real world performance, there is no difference in speed or actually any difference at all in the drive its self.

SATA drives will transfer in "spurts" of up to about 80 meg per second.
Sustained transfer rates over an extended time will be much, much lower, around 4-8 meg per second, depending on the drive.

SATA drives usually have a "faster" initial access speed, so they "feel" fast just clicking around with your mouse, and doing simple tasks.
SCSI drives will have a more "sluggish" feel doing the same thing, unless it is one of the top of the line 10,000 rpm SCSI drives.

The main difference/advantage a SCSI drive has over SATA is they maintain higher sustained transfer rates over time, like 40 meg per second.

Pretty useless for for the vast majority of desktop PC's.

Games and application programs do not transfer large amounts of data for extended periods of time. A game or application will move for instance 20-200 meg of information from the drive into main memory for a few seconds when first loading, then drop down to only a few meg of information actually needed from the drive every so often as you go along playing or working.

SCSI drive's are better for servers, where there are numerous workstations constantly moving information back forth from the drives on the server, or large files being constantly moved or accessed, that's where the sustained transfer rate of the SCSI drives can show their stuff.

SATA drives are inexpensive, most modern motherboards are built with SATA on board controllers.

SCSI drives are expensive, SCSI drive controllers (at least a good one that can keep up with the drive's potential) are very expensive. Most motherboards built for severs will have SCSI controllers on board, but again, just check the price. They are hugely expensive, mostly because of the built in SCSI controller.
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