Need Another Hard Drive!

[Septic]

I'm desperately in need of some hard drive space right now! Anybody know where I can get a good 120 - 200 gig hard drive for around $200 - $300 ?

[redd18]

you should be able to pick a 120 gigger at comp usa or best buy....for under 300...shouldnt you?

[Septic]

I'm thinking of going with this one unless somebody knows of anything better. I know SCSI is faster, but I just need lots of space right now and this is the best offer I could find. Let me know if you know of anything better.

[kai_]

i hope thats an error where it says 5200 rpms get a 7200 rpm with the lowest access time possible. I like the WDXXXXJB's the ones with 8mb cache i own two 100gb of them in raid 0

[Septic]

What do the RAID levels mean? My dad has a ten drive 36-gig SCSI Ultra160 RAID 5 set up but what does the RAID 5 mean?

[kai_]

Linear mode
Two or more disks are combined into one physical device. The disks are ``appended'' to each other, so writing to the RAID device will fill up disk 0 first, then disk 1 and so on. The disks does not have to be of the same size. In fact, size doesn't matter at all here
There is no redundancy in this level. If one disk crashes you will most probably lose all your data. You can however be lucky to recover some data, since the filesystem will just be missing one large consecutive chunk of data.
The read and write performance will not increase for single reads/writes. But if several users use the device, you may be lucky that one user effectively is using the first disk, and the other user is accessing files which happen to reside on the second disk. If that happens, you will see a performance gain.
RAID-0
Also called ``stripe'' mode. Like linear mode, except that reads and writes are done in parallel to the devices. The devices should have approximately the same size. Since all access is done in parallel, the devices fill up equally. If one device is much larger than the other devices, that extra space is still utilized in the RAID device, but you will be accessing this larger disk alone, during writes in the high end of your RAID device. This of course hurts performance.
Like linear, there's no redundancy in this level either. Unlike linear mode, you will not be able to rescue any data if a drive fails. If you remove a drive from a RAID-0 set, the RAID device will not just miss one consecutive block of data, it will be filled with small holes all over the device. e2fsck will probably not be able to recover much from such a device.
The read and write performance will increase, because reads and writes are done in parallel on the devices. This is usually the main reason for running RAID-0. If the busses to the disks are fast enough, you can get very close to N*P MB/sec.
RAID-1
This is the first mode which actually has redundancy. RAID-1 can be used on two or more disks with zero or more spare-disks. This mode maintains an exact mirror of the information on one disk on the other disk(s). Of Course, the disks must be of equal size. If one disk is larger than another, your RAID device will be the size of the smallest disk.
If up to N-1 disks are removed (or crashes), all data are still intact. If there are spare disks available, and if the system (eg. SCSI drivers or IDE chipset etc.) survived the crash, reconstruction of the mirror will immediately begin on one of the spare disks, after detection of the drive fault.
Write performance is the slightly worse than on a single device, because identical copies of the data written must be sent to every disk in the array. Read performance is usually pretty bad because of an oversimplified read-balancing strategy in the RAID code. However, there has been implemented a much improved read-balancing strategy, which might be available for the Linux-2.2 RAID patches (ask on the linux-kernel list), and which will most likely be in the standard 2.4 kernel RAID support.
RAID-4
This RAID level is not used very often. It can be used on three or more disks. Instead of completely mirroring the information, it keeps parity information on one drive, and writes data to the other disks in a RAID-0 like way. Because one disks is reserved for parity information, the size of the array will be (N-1)*S, where S is the size of the smallest drive in the array. As in RAID-1, the disks should either be of equal size, or you will just have to accept that the S in the (N-1)*S formula above will be the size of the smallest drive in the array.
If one drive fails, the parity information can be used to reconstruct all data. If two drives fail, all data is lost.
The reason this level is not more frequently used, is because the parity information is kept on one drive. This information must be updated every time one of the other disks are written to. Thus, the parity disk will become a bottleneck, if it is not a lot faster than the other disks. However, if you just happen to have a lot of slow disks and a very fast one, this RAID level can be very useful.
RAID-5
This is perhaps the most useful RAID mode when one wishes to combine a larger number of physical disks, and still maintain some redundancy. RAID-5 can be used on three or more disks, with zero or more spare-disks. The resulting RAID-5 device size will be (N-1)*S, just like RAID-4. The big difference between RAID-5 and -4 is, that the parity information is distributed evenly among the participating drives, avoiding the bottleneck problem in RAID-4.
If one of the disks fail, all data are still intact, thanks to the parity information. If spare disks are available, reconstruction will begin immediately after the device failure. If two disks fail simultaneously, all data are lost. RAID-5 can survive one disk failure, but not two or more.
Both read and write performance usually increase, but it's hard to predict how much.

[Septic]

Wow! Very informative! Thanks!

[MasJ]

That seriously sounds like some cut n paste
Septic, did you look for an external hard drive, I think you should be able to buy some off some company or something, a 3 Terabyte external HDD comes pretty cheap you know...

[Septic]

Where do you get a 3 terabyte external hard drive? All the external hard drives I looked at on sites were priced higher than the internal ones.

[kai_]

Originally posted by MasJ
That seriously sounds like some cut n paste
Septic, did you look for an external hard drive, I think you should be able to buy some off some company or something, a 3 Terabyte external HDD comes pretty cheap you know...

it was cute and paste from a linux raid manual , it was 3 am.

[Sephires]

In general external hard drives are more expensive. Hell i could go to Staples right now and and get a hard drive just as big, faster and cheaper than the one you posted.

[kai_]

Originally posted by MasJ
That seriously sounds like some cut n paste
Septic, did you look for an external hard drive, I think you should be able to buy some off some company or something, a 3 Terabyte external HDD comes pretty cheap you know...

no such thing as a 3 terabyte hard drive

[Astro X]

Yeah, external Harddrive is generally more expensive due to easy set up and you don't have to the drive inside your com physically.

Before adding new HD, make sure you have enough IDE ports. For my computer, I have 4 IDE ports. 2 for my CD-writer and DVD ROM, 2 for my two physical HD(master and slave).

[Nitramuse]

Uhmmm that's standard....2 IDE cables, wich you can attach 2 devices one each IDE. One master and slave on each cable.

[Nimhloth]

Septic. If you don't mind buying online and want a good price I suggest looking at www.pricewatch.com

They have killer prices.