IDE and SATA

Could someone please explain the difference between IDE and Serial ATA drives, and why it is better to use SATA drives when building Geovision systems.

Thanks

It's an interface differance. SATA allows for much faster transer speeds then IDE. Right now they both max out at about 133mb/s for IDE and 150 mb/s for SATA. The differance is that that speed is the absolute limit of IDE and the first generation of limits for SATA. The next gen (backwards compatable) will probley be 200 mb/s. This means faster loading times for programs and faster write times. SATA is also suppose to bridge the last bit of the gap between IDE and SCSI.

SATA also elimanates a few minor headaches with the configuring of drives. SATA doesn't have the master/slave/cable select settings of IDE. Since you're putting one drive to one cable you don't need it. The internals of the SATA controlers on the drives themselves are a bit more flexiable then IDE controlers and some of the lessions from the past have been added. It will be easier for SATA to adapt to new tech and not have some of the hacks that IDE had to accept (LBA, drive limits, ect.) SATA will also have a better version of the SMART (Self Monitoring Analisys Reporting Tool) that hopefully will allow techs is see failing drives earlier with less chance of data loss. You also get the minor benfit of better air flow with the smaller cables, and they claim they will be a bit more effcent in the power the drives use.

Alright, that is all of the theory stuff, and I'm sure what matters most to the people reading is the hard reality. Right now almost all of the drives you buy as SATA drives are just IDE drives with an adaptor built on to accept the SATA cables. So you aren't getting a huge amount of benfit from the drives except that you can use more advanced motherboards and keep those drives in place till then.

Thanks Thomas. So how do you connect the SATA HDDs, If you're not using the IDE1 and IDE2 connectors, where do you connect them to, and would you require a different form of cable?

Yep, you use a differant cable for both power and connection. The voltage is the same and you can get power adapters for IDE to SATA and back. The SATA drive controler is generally in the same place and hooks up in the same way.

Tom, dont most newer high end Motherboards, have sata plugs built in these days?

You also get the minor benfit of better air flow with the smaller cables, and they claim they will be a bit more effcent in the power the drives use.

I would not call that a minor benifit at all, not in this country where it is always hot

Most Mobos do, not all power supplies do.

whats the difference between these, SCSI, Promise PCI Cards, etc?

SATA: The latest drive standard. Probley going to replace both IDE and SCSI. Right now it's on par with IDE and just behind SCSI in performance. It's got excellent speed and has some of the lessons learned from the past built into it. One wire to one connector, usually four connectors to a mother board.

IDE: The long time standard for desktop drives. It's hit the end of life, the speeds been maxed out and it's starting to show it's age. Within the next few years they will be gone. Two drives to a cable, two connectors to a board.

SCSI: Server grade drives. For when 99.99% uptime isn't good enough. These drives cost quite a bit, but you're getting what you pay for. Seems to have hit the limits of it's speed and capacity. SATA and IDE are catching up in quaility and speed. SCSI can connect any number and types of devices in a daisy chain, much like PTZ cameras. (Typing this made me realise it's almost exactly the same.)

Promise cards, RAID in general: RAID stands for Redunant arrary of inexpensive disks. It's a way of combining multiple drives to look like one drive to the OS. RAID can be setup in a lot of differant ways but RAID 0 and RAID 5 are the most comman. RAID 0 does what's called striping, it takes advantage of the PCI bus's faster speeds to write chunks of data to differant disks. So part of file A is on disk 1 and 2. This allows for faster read/writes. RAID 5 sets aside chunks of disk to act as backups of the other disks. So four 250 GB drives show up as 750 GB to the computer. But that lost storage space allows for swapping out dead drives. So if drive 1 fails, pull it, put in a new one, give the card a few moments and voilia, no loss of data.

RAID cards run from $30 up to $10,000 (for prebuilt 2.5 TB boxes in RAID 5). The more you spend, the better the card is. The cheap ones are fine for RAID 0 but won't do RAID 5. RAID 5 can be a wonderful tool, and probley an excellent selling point for PC based DVRs. You can tell a client "yep, it costs a little more, but you never have to worry about losing data."

Thanks thomas You know your stuff ..

Im a little behind these days (well majorly), spent to much time over the past 6 years in the alarm industry, then the last 3 in the CCTV Im tyring to get back up.. wont be easy, or cheap .. (I was one of those DOS geeks back in the day, and started making web sites from when windows 95 first came out, and writing ASP sites from almost day 1 of ASP, never gave up the web development just took a break on and off) I know the standard stuff, just not too deep.

Rory

We've been using SATA in our DVR's for the last 3 months. Very nice! Have over 250 in the field with no problems.