7200rpm and 8mb cache? external harddrives

[slimpickins]

hi, i have found out which brands are reliable, but what does cache mean and 7200rpm, is there a glossary

[slimpickins]

nothing in the glossary about these

[junx0r]

rpm = revolutions per minute, how fast it goes. Faster is better, 7200 is good.
cache = like a mini RAM memory chip, stores info to transfer, more = better.

http://en.wikipedia.org/wiki/Cache
http://en.wikipedia.org/wiki/Hard_drive

[slimpickins]

hi, ive seen seagate hardrives, some range from 2mb 250gig, to 16meg 250gig, i dont understand 16meg is not that much, what exactly does it do, what happens if i go for a lower meg, is it slower or can it corrupt my transfers, i will be backing up dvd's onto these hardrives, they are not music or phtots but big files

[redwudz]

8 MB caches are pretty standard, especially in larger drives. A larger 16MB cache may make for more efficient transfers, but 8MB should be sufficient for most uses. The larger cache may be of more benefit if you have a lot of small files being transfered as it should improve access time, such as working with a database. I doubt that most of us would notice any difference in transfer speeds between the two size caches, especially with larger files. You shouldn't have any corruption problems no matter what size your cache is.

And this thread would be better suited to the Computer forum. Moving you.

[slimpickins]

so it has nothing to do with the transfer stablility, i dont want to try and asave money only to realise ive shot myself in the foot, if i do back-up dvd's to the external drive, what is the chances of them becoming corrupt, basically hwat bad can happen (i.e loss of quality and glitches)

[slimpickins]

also, what does the 1394 stand for when used like this usb 2.0/1394, the 1394 has added 38pounds ($70) to the harddrive
plus the drive with 1394 has8mb and the one without it has 16mb

8mb+1394=238gbp / 16mb no 1394 = 200

[JohnnyMalaria]

also, what does the 1394 stand for when used like this usb 2.0/1394, the 1394 has added 38pounds ($70) to the harddrive
plus the drive with 1394 has8mb and the one without it has 16mb

It means that it has two different types of interface for connecting it to your computer - USB 2.0 and IEEE-1394 (FireWire). It depends on your system which interface you will want to use. First off, if you only have USB 1.1, the performance will be slower. To use the FireWire port, you will either have to plug it in to the same FireWire interface as your camcorder or daisy chain it with your camcorder. What that means is plug the camcorder's firewire cable into the harddrive and the harddrive into the computer.

In my experience, the USB interface has proven less troublesome. For some reason, my external drives with USB and Firewire sometimes don't get recognized by Windows via Firewire but always do by USB.

As far as cache size, corruption etc, "forget about it" (use lame attempt at NY Italian accent here). Nearly every modern harddrive (if not every), performs write verification - i.e., it checks that what it was meant to write did get written. Also, for added peace of mind, after copying files to the drive, you can verify them - byte for byte - against the original.

Finally, most external drives come ready to run, preformatted with the FAT32 file system. This limits the maximum file size to 4GB. That may or may not be a problem depending on your particular need. Windows XP supports the NTFS file system - unlimited file size and, more importantly, every time the computer writes something to an NTFS-formatted drive, the operating system verifies it. If something wrong happens, you find out there and then. In fact, XP will try to write again. So, if the copy seems to go without a hitch then you are assured that the drive contains exactly what it should. Of course, should you drop the drive, run over it or whatever, that could corrupt the data!!! Personally, I always reformat my external drives to NTFS.

[slimpickins]

i definatly need ntfs, i will be moving dvd files, but then again they are in 1gig video files as standard, but i will want the write veriufication one by the operating systme, someone was saying i fu used the operating system to format it to ntfs its not as good as as the drive software

[JohnnyMalaria]

if u used the operating system to format it to ntfs its not as good as as the drive software

There are two types of formatting - low level and high level. Low level is done by the drive manufacturer at the factory. Think of it as allocating parts of the drive to store the raw 0s and 1s of the data. It takes care of parts of the drive that are unusable (inherent defects). This acts like the primer or undercoat to receive a more structured, operating system specific layout of the data - e.g., FAT32 or NTFS. I really don't see a disadvantage to changing the high level format from whatever file system the drive comes with to a different one except that some older operating systems won't understand it, mainly Win9x. Windows 2000 and NT4 will.

John.

[slimpickins]

what problems will a 2mb cache present, all i need top do is load a load of dvd's files on there so i can take it with my laptop
does the cache effect transfer speed, browsing a load of small files?
i already messed up by buying a packard bell, il go for seagate
was going to go for the western digital my book but people say that is crap at the moment

thanks

[JohnnyMalaria]

For watching DVDs, the cache size won't affect you.

One thing the cache does is this:

Let's say you are running a program and it needs 100 bytes of data from a location on the hard drive. The hard drive reads that 100 bytes and sends it. Now you need another 100 bytes - the hard drive reads that 100 bytes and sends it etc. Very often the bits of data requested are next to each other so, like any self-respecting lazy person, the hard drive does the running around just once but brings back 2 megabytes of data and stores it in its own memory. It gives the 100 bytes originally requested to the computer. The next request comes in and - aha! - now the hard drive just has to look in its local memory for the information. If it's there, that's all. A lot quicker and a lot less wear and tear on the drive. Of course, if a request comes in for data not in the cache, then it has to go back to the disk itself for the information - which also takes longer.

For DVDs, the cache will hold perhaps a few seconds of video. The operating system will also have a "cache" or, more correctly, a buffer to hold more information than actually needed to allow for delays in information arriving. i.e., the OS will usually request video in large chunks, not just a frame at a time.

Between the OS and the hard drive cache, you'll get smooth playback.

As long as you go with a reputable brand, disable unnecessary background software etc, you'll be good to go.

Regarding "7200rpm" - this is how fast the disks inside the hard drive spin. The faster the spinning, the quicker the hard drive can find data and transfer it. These days, 7200rpm is plenty for DVD playback. 7200rpm means 7200 revolutions per minute, or 120 per second.

John.

[jimmalenko]

@slimpickins - Please learn to use Google - it can't solve the world's problems, but it does a bang-up job of answering questions such as the "flood" you've had in the past few days

[slimpickins]

i know jimmalenko, ive had a lot ofo questions recently, but look at the bright side, soon ill be able to answer someone else's flood of questions
in my defence i searched goodgle for hourse for reviews and such but came up empty, also ive searched for defenitions but it was either to complicated or irrelivant