SATA vs ATA?

An anonymous reader asks: "I have a client that needs a server with quite a bit of storage, reasonable level of reliability and redundancy and all for as cheap as possible. In other words they need a server with a RAID array using a number or large hard drives. Since SCSI is still more expensive than ATA (or SATA), I'm looking to using either an ATA or a SATA RAID controller from Promise Technologies. While I had initially was planning on using SATA drives, I have read some material recently to make me rethink that decision and stick with ATA drives. What kind of experiences (good and bad) have people had with SATA drives as compared to ATA drives, especially in a server type environment?"

Don't use Promise, for one thing

[b00m3rang]

Promise and Highpoint (and any other cheap raid card) in my experience are no more than an IDE card with RAID software that eats up CPU cycles. Recovery options for a lost drive member are usually limited and unreliable. If you want reasonable reliability, go with one of the drives that uses SCSI hardware adapted to an SATA interface (such as WD Raptor). I would personally recommend Adaptec for your host controller needs, as they do the RAID in hardware.

Re:Don't use Promise, for one thing

[UserChrisCanter4]

Don't confuse the fact that Promise produces on-mobo RAID "hardware" with the impression that all of their equipment is like that. Promise makes several truly hardware-based SATA and ATA cards, as well as a few enclosures that take numerous (4-16) IDE drives, do RAID in hardware, and interface to a server over U160 SCSI. They are perfectly capable of making hardware RAID solutions, provided you're willing to buy something other than a $60 "RAID" card.

Their only major drawback I saw last time I looked at their hardware was that Linux drivers at the time tended to be binary and proprietary to specific versions (works on redhat but not Suse, etc.), which may or may not matter depending upon the OS you're choosing to run.

I don't work for them, and I don't even use their equipment in any of my stuff (a buddy of mine runs an SX4000 card, though, so I have seen them in action), but I do get a bit peeved when someone dismisses a company's higher-end solutions because of (admittedly) bad experience with their low-end kit.

Look at Apple's Xserve RAID

[caseih]

Apple's XServer RAID solution seems to be one of the cheapest dollar per gigabyte solution that I've ever seen. They use fast ATA drives. Although ATA drives can have problems, Apple uses only the best drives from each lot (hence they are a bit more expensive than if you bought the disks from a jobber). The RAID is a true hardware raid, allowing the creation of a hot-spare, e-mail notification, etc. The configuration software is java and runs on any platform. The RAID unit itself is fibre channel, so it can hook to servers running any OS and looks just like a big scsi disk. We have our arrays set up such that we're mirroring 2 phyiscally sparate arrays together (each raid 5+ hot spare), so we can lose up to 4 disks wihout any loss of data. Each array is about 2 or 3 raw terrabytes.

I would avoid the other controller cards you mentioned for the reasons the other posters mentioned. The Xserve RAID is all the benifits of a good scsi backplane (RAID, monitoring, etc) for a fraction of the cost.

Re:Dangers of using ATA or SATA for Raid

[Guspaz]

This would be why professional ATA RAID solutions have battery backup. Somebody previously linked to Apple's XServe solution. It has enough battery backup power built in to keep the caches going for 24 hours. If you can't find a power source for your server within 24 hours of a power failure, your data obviously isn't that important.

First off I'd assume if your data is so important you're going to have UPS and generators. If you don't have a generator, and the power fails, great, you've got 24 hours to purchase one. A 1500W generator costs about 450$ US, and should be more than powerfull enough to run your server, AND network connectivity. You'll not only keep your server happy during a power failure, you'll be able to keep using the server.

Anyhow, this post started out about the battery backup. What you stated as a major problem isn't one, since serious ATA RAID solutions have battery backup.

Don't Confuse

[Crypt0pimP]

The connection technology with the drive / spindle quality.

(P)ATA and SATA are connection technologies.
They have their individual benefits and drawbacks
(cost, reliability, speed)

The real factors to consider are the details of the drives themselves - vibration dampening, bearing and motor quality, MTBF.

It used to be rather simple to guess what quality of drive you were buying. If it was 146GB or less (73GB, 36GB), and rotational speed was 10K or 15K, it was either SCSI or FC, and an "enterprise" class drive, rated in Mean Time Between Failure.

Good drive, high quality, expect it to last several years, spinning 24 hours a day, sustaining high read and write activity during production and backup hours.

If the drive was larger (200GB+) and slower (7200 RPM), typically an ATA drive, maybe low end SCSI.

Then it was, at best, a workstation class drive, rated in "Contact Start Stops", meaning how many spin-ups and shutdowns the drive should survive. Not meant to run 24 hours a day, and run under heavy load except for short periods.

The lines are beginning to blur with 300 - 500 GB drives with FC drive attachment. Those drives are meant for archiving and reference data. Not production databases and such.

In my personal experience, the 3Ware products are worth the premium.

Pick your attachment technology as appropriate.

Best of Luck,
Patrick (slineyp at hotmail dot com)

Re:My experience with RAID cards

[FlameSnyper]

Probably because it sucks down all your CPU speed when you run the test. The faster your CPU, the faster the software RAID.

The hardware raid controllers have limited clock speeds and less RAM than your computer, so they're slower.

Re:Dangers of using ATA or SATA for Raid

[bruthasj]

You may want to read this whitepaper...

And, yeah! Guess what? Buy their software to fix it! Move along ...

I wouldn't advise using something other than SCSI without understanding the ramifications.

Uh, would you advise to use anything without understanding the ramifications?