Hard Drive Cache and Other Specifications

JokkeJokke Bergen, Norway Icrontian
edited January 2008 in Hardware
Ok, I didn't want to make a new thread, so I'm just gonna continue this one. I'm looking for a HD, max price 600 NOK (ca. $120), around 320 GB. As mentioned, I'm looking at the Samsung Spinpoint T166. However, I have a few noob questions: what is "cache"? What's the difference between SATA and SATA-II? I've also noted that some Seagate Drives are 7200.10, and others are 7200.11, and other yet are 7200.2. What's the difference? What is the ms? I can se it ranging from 3.5-11.0. how does RPM affect performance, noise level and longevity? And finally I've just glanced at some external HD, and I'm wondering what is eSATA?

I'm sorry if it seems like stupid questions..

Comments

  • LeonardoLeonardo Wake up and smell the glaciers Eagle River, Alaska Icrontian
    edited November 2007
    I don't know the difference between 7200.10 and .11. Cache is onboard memory. It is a physical memory chip mounted on the logic board of the hard drive unit. It's temporary storage device as data surges to the hard drive and from the hard drive. It helps buffer the inconsistent flow of data that otherwise might overwhelm the hard drives speed limitations. With any new hard drive, always look for minimum cache size of 8MB and a minimum rotational speed 7200 RPM. I have an older Samsung Spinpoint hard drive with only 2MB cache. It's a very smooth, quiet, reliable drive, but the minimal cache makes it noticeably slower than other my other drives in the same class.

    Jokke, I'm spinning this off (pardon the pun) as a separate thread. It's worthy of opening a new topic. Very good questions you asked.
  • kryystkryyst Ontario, Canada
    edited November 2007
    Keep in mind though it's an external drive. So the bottle neck isn't how fast the drive goes, it's still way faster then the USB connection provides. Sata vs Sata 2 is a bandwidth thing, but you won't notice a difference over USB. More cache on an external drive is handy, but again you will only get a partial realization because it bottle necks through the usb.

    So, that being said at the end of the day. If the price difference between a slower usb drive and a faster one is minor (say 10%) get the faster one. Otherwise the cost for speed is wasted. The only qualifier is that if this is a drive you want to perhaps swap and place internally then there is benefit of getting a faster external drive.

    If you are worried about noise or heat, get an external drive based on a 2.5 inch drive, but they cost more. If data size is your goal you'll have to go 3.5.
  • mas0nmas0n howdy Icrontian
    edited November 2007
    All this talk about USB severely limiting your transfer speeds to external hard drives brings us up to your last question. eSATA is an external SATA connection that provides very fast transfer speeds (the same as internal SATA) in exchange for relatively short cables. The connector for eSATA differs slightly from that of a regular SATA cable and so you must either have the interface built into your motherboard or have an adapter (internal SATA --> eSATA) which some eSATA drives come with.
  • beavissbeaviss
    edited January 2008
    Hi,

    Can somebody please help answer this question.

    I have 4 hdd's in RAID 10.

    I recently lost one and was only able to get one exactly the same size, but it has double the cache.

    Setup is now 3 x WD2500JS (250GB) hard drive 7200rpm with 8 MB cache.
    1 x WD2500AAJS-2 (250 GB) 7200 16 MB cache.

    Will the extra cache on the one drive cause and problems ? It is a little faster than the others.

    Your response greatly appreciated.
  • ThraxThrax 🐌 Austin, TX Icrontian
    edited January 2008
    Shouldn't make a difference.
  • beavissbeaviss
    edited January 2008
    Gr8 Thx for your quick response.

    Feel safer now :)
  • beavissbeaviss
    edited January 2008
    Hi again Guys,

    After rebooting, the array has to be rebuilt quite often. 2 disks normally are labelled 'error occured" and degraded.

    The rest of the setup is as follows if perhaps you see something amis.

    Apparently the cache size is the same (WD2500AAJS-2 has an 8MB cache)

    Gigabyte 460W PSU
    C2D quad @ 2.4ghz
    3 x WD 2500JS sata drives + 1x WD2500AAJS-2 in Raid10
    Gigabyte liquid cooler (3d galaxy II)
    8800 GTS 320MB
    p35-DQ6 mobo (gigabyte)
    4GB Ram
    3D aurora chassis with 3 x 120mm Fans
    Vista 32 bit ?

    Could power be a concern ? I am able to play games fine, no artifacts visible, very smooth.

    Wondering if I shouldnt then use the new drive as boot drive and set the other 3 to raid0 - do have 500gb seagate freeagent backup drive - ugh...

    Thanks, your advice will be greatly appreciated.
  • kryystkryyst Ontario, Canada
    edited January 2008
    Power would definitely be my first guess you've got a hell of a lot in that thing for a little 460w PSU I'd say you should be running a 600w PSU in that machine.

    Though that shouldn't normally effect the raid. Are you getting random shutdowns or lockups or any other symptoms?
  • beavissbeaviss
    edited January 2008
    Hi,

    I occassionally have power failures, though the ups does always trigger a shutdown in time, and the machine shuts down normally each time with quite a bit of power left in the ups.

    This also occurs even on normal shutdowns or reboots. Very confusing. Do you think then I should first try to upgade my PSU ? I do have a 650W spare, but the ups simply cant handle load. Its a Mecer 800va.

    Thanks.
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