can scsi & raid work together? 1

[estesflyer]

first of all, what is so special about scsi drives other than their faster rpm's, and faster seek time? I mean, ide drives have reached 10k rpm's, but i guess not the ms...

So tell me, what IS seek time? How important is it and what kind of difference does it make speed wise?

Second of all, would it be possible to connect two 9 gig scsi drives together to make an 18 gig scsi raid drive?

would it be better to just use 10k rpm ide drives for this? I know it would be a lot cheaper, and since I'm not going to be running a server, would it really improve performance that much considering I would be having 768 megs ddr 2700 memory, and athlon xp 1800, etc...

any suggestions for a board that would support all that btw??

And another thing, what exactly IS raid... I've heard of it, know friends that use it, but i am still not exactly sure WHAT it does. Does it combine the drives to make them both work simultaneously to perform faster? Or what?

TIA

- Rusty - Rusty

 

[Laffalot]

Hi WOW what a loaded post.

So what is seek time

Seek Time is the time taken for the program to find the required data on the hard drive.
Seek Time is in the order of 12 +/- 4 ms for most Drives. The faster the seek time the quicker the information is retrieved for processing. However although SEEK time has become known as the time to retrieve the data this was no always true as the Total time = Seek Time + Read Time. Where the read time is the time it takes to read the data once the head has found it. This of course is faster than the seek time and depends upon the speed of rotation of the head

What Is RAID.

Well RAID or (Redundant Array of Inexpensive Disks) is a method of Fault Tolerance in data storage systems. There are different levels of RAID each having their Pros and Cons.
The lowest level is RAID0 (Zero). Although not strictly fault tolerant , it spreads the data over multiple drives. The advantage of it is that is does increase access time to the data if multiple disk controllers are used. And also you get all of the disk space to play with. However if you lose a drive, its Fenito Benito to your data.


The highest level being RAID5. This level stores the data and parity information on different disks. If a disk fails the system can recover the information by using the parity bits on the unaffected drive. The disadvantage however is that is hungry for disk space and uses up more space for the same amount of data.

Now this may have changed (I did hear of a IDE RAID interface) but RAID always used to be SCSI as RAID systems used multiple disk drives, the more the merrier and that's what NT supported.

I would probably go for a Ultra Wide SCSI and IDE drives that way you can access both types of drives simultaneously. Keep you OS on one and Programs on the other.
Any Help, Yes/No let me know

Regards

________________________________________
Is not a fool a wise man in his own eyes - Proverbs

 

[Techtony]

We're up to RAID8 now. As to a 10K IDE drive, never heard of it. Checked Ingram Micro, the international hardware jobber that supplies your local superstores, and they haven't heard of it. Can't find one at Maxtor or WD. Where is this mysterious 10K IDE drive?

 

[butchrecon]

IBM has a 10K RPM dirve. I dont think it is for sale yet. But they have been testing them. James Collins
Field Service Engineer
A+, MCP

email: butchrecon@skyenet.net

Please let us (Tek-tips members) know if the solutions we provide are helpful to you. Not only do they help you but they may help others.

 

[Maruis]

Just to add to the previous posts...

The reason why companies use SCSI instead of IDE drives for there servers are:
With IDE you can only connect 2 IDE devices per IDE controller.
With SCSI you can connect 15 SCSI devices to a SCSI controller. (in some cases even more depending on your controller)
SCSI is a lot faster than IDE iro bus tranfers.
SCSI drives are more robust than IDE drives, they last a lot longer.

Hopes this helps you

 

[Tels]

Just a note to that above, I'm pretty sure there are IDE RAID arrays out there, when I got my m'board I saw a couple of unsoldered slots labelled RAID IDE.........
but there were still only 2 of em... guess it's low level raid (mirroring or something like that)

for pint$ = 1 to 20
for pint$ = pint$ + 1
if pint$ = 20 goto HOME
next pint$

 

[Maruis]

Did some research
There are IDE raid's out there..

http://www.raidweb.com/ide.html

According to this site they claim to have bus tranfer speeds of up to 100 Mbs.
As far as I know the fastest transfer rate on IDE is 33Mbs.(please correct me if I am wrong)

SCSI has bus tranfer speeds of 160 Mbs very hard for IDE to beat.

Hope this help a little bit more.

 

[butchrecon]

Isnt ATA100 100Mbs per second? That will explain why the IDE RAID is 100Mbs/sec. James Collins
Field Service Engineer
A+, MCP

email: butchrecon@skyenet.net

Please let us (Tek-tips members) know if the solutions we provide are helpful to you. Not only do they help you but they may help others.

 

[Maruis]

K some follow up on previous post on IDE bus speed....

According to the following URL:

http://www.digit-life.com/articles/intelata/

The tested speed on IDE reached about 85 Mbs this means it is about half the speed on a Ultra 160 SCSI bus.

http://www.pcguide.com/ref/hdd/if/scsi/protSpeed-c.html

Hope this shed's more light on the subject

 

[Tels]

Even so, using RAID 0 with IDE you would get some pretty decent access times for a cheap price.... Bad idea for critical data though...

Offers a nice alternative to SCSI RAID arrays all the same

Tels

Win2000 Network Administrator for pint$ = 1 to 20
for pint$ = pint$ + 1
if pint$ = 20 goto HOME
next pint$

 

[Guest_imported]

what should I do if I want to Add and Detect my 20 GB IDE harddisk in my SCSI RAID1 as a system ?

 

[CitrixEngineer]

A couple of points worth noting;

100MB/sec is the theoretical burst rate of IDE 100.

This means, that the quickest it can manage in a peak is (theoretically) 100MB in a second.

This should be contrasted with sustained data transfer rate, or the rate at which it can continuously provide data. This is typically 33MB/sec. I believe this is down to the 33Mhz limitation of the PCI bus, but can't find any links to back it up right now.

On higher end servers, with 64-bit PCI subsystems, a U/W SCSI setup will reach burst rates of 160MB/sec, with sustained rates approaching nearly double that of ATA 100.

I know of 10 RAID levels, 0 - 7, 10, 53 and 0+1.

http://www.acnc.com/raid.html

I believe that IDE RAID is currently limited to levels 0, 1 (0+1), 5 and possibly 10.

http://www4.tomshardware.com/storage/00q1/000329/

I hope this information is useful

 

[Tels]

If you have a SCSI RAID system, and you want to put in an IDE100 drive, you'll either have IDE connectors on the board or you'll have to buy an IDE compatible card.... thats it really

please update me if I'm off this one

Tels (real early in the morning)


Win2000 Network Administrator

 

[Guest_imported]

Wow! All those certifications replied and none of them explained disk striping. No wonder I always win the contracts!!! Depending upon which operating system you choose, or even which disk management software you might purchase, look into stripe sets for your 2 drives to create a single volume. Cheers!