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?"

Comments

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

[afidel]

Their IDE RAID card, the SuperTrak SX6000 does REALLY poorly at some tasks. It eats CPU and from mailing lists has a lot of problems recovering from drive failures. For a good comparison to other ATA RAID cards see this storage review writeup on it.

Dangers of using ATA or SATA for Raid

[DocSponge]

You may want to read this whitepaper and see what they have to say about using ata or sata drives in a raid configuration. It is possible, due to the use of write-back caching, to lose the integrity of the raid array and lose your data eliminating any intial cost benefits. To quote the paper:

Though performance enhancement is helpful, the use use of write back caching in ATA RAID implementations presents at least two severe reliability drawbacks. The first involves the integrity of the data in the write back cache during a power failure event. When power is suddenly lost in the drive bays, the data located in the cache memories of the drives is also lost. In fact, in addition to data loss, the drive may also have reordered any pending writes in its write back cache. Because this data has been already committed as a write from the standpoint of the application, this may make it impossible for the application to perform consisten crash recovery. When this type of corruption occurs, it not only causes data loss to specific applications at specific places on the drive but can frequently corrupt filesystems and effectively cause the loss of all data on the "damaged" disk.

Trying to remedy this by turning off write-back caching severly impacts the performance of the drives and some vendors do not certify the recovery of drives that deactivate write-back caching so this may increase failure rates.

Losing data on an ata raid array happened to a friend of mine and I wouldn't advise using something other than SCSI without understanding the ramifications.

Best regards,

Doc

I made a new years resolution to give up sigs...so far so good!

Client/Server

[soundsop]

I have a client that needs a server.

On a related note, I was having dinner at a restaurant and my waiter asked me for a recommendation for a good email program. So I guess it turns outs that I have a server that needs a client.

Re:Buy a RAID

[Guspaz]

You may be right about building a system as reliable, and it'd certainly be hard to compete with it from a size standpoint, you are totally wrong about it being inexpensive.

Apple's 3.5TB system costs $10,999 US. If you were to build a system that comprised 9 Hitachi 7200RPM 400GB drives, you would acheive 100GB more storage space for 3,600$ plus the cost of the server it was hosted in. Throw in 750$ for a high-end RAID card and 1000$ for a server to enclose and handle it, and you're still priced at under HALF the price of Apple's solution.

So, in conclusion, Apple's solution is many things, and is certainly VERY sexy and attractive. But inexpensive compared to a self-built solution it is NOT.

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)