Okay, on further analysis...
I have been researching these for a while now and it looks like the best option is the LSI Logic card. Unfortunately it is not yet available! Some of the benefits:
6 channel (4 would be fine...but hey, why not 6)
Integrated 100MHz RAM Cache (64MB)
Management support (no big deal)
80302 Processor
64-bit, 66MHz PCI 2.2 <= the main reason I am waiting
SATA Hot Swap
They have been doing this for a LONG time!
The down side:
Not available today
No idea of pricing
There are no other 64-bit 66MHz cards out there. Some are 64-bit (3-ware), some are 66MHz (Promise and others). None of the others has (or at least advertises) any Cache on the board. By the way, the 3-wire site has benchmarks for Parallel and Serial ATA. The data is essentially identical, thus, there is really no advantage to SATA over Parallel ATA. I was talking to someone about this earlier today. I am not sure if there will ever be a performance reason to use SATA over Parallel ATA as far as performance...at least not for quite a while. Here is my justification (flame me as you please!)
1 - A single drive today has a miximum internal xfr rate of about 85MB/s. Max sustained is 32-58MB/s. This is the value we really care about.
2 - Most RAID adapters (ATA) force 1 drive / channel. I know...Promise offers 2/channel on some cards...I did say most!
3 - 58MB/s < 100MB/s < 133MB/s < 150MB/s, thus, even ATA-100 is sufficient for todays technology
4 - Technology will get better, thus, in the next few years I can see internal xfr rates up to the 133MB/s range
5 - Thus, SATA will not buy you any performance over the next few years.
Now, all of the above is valid with the exception of two points (which may be significant!)
1 - For the RAID adapters that allow two drives on the same channel, the maximum transfer rate you can get from two drives is 116MB/s, which is less than the 133MB/s transfer rate you get with ATA-133, still no bottleneck.
a. From PuckMan's law of thermo-datanics ;-> there is no way you will even get there because:
i. You only get the 58MB/s on the outer tracks of the drive, the drive will get slower as you do I/O from the inner cylendars
ii. Master / Slave sux, thus, you won't get to use all the bandwidth anyhow as only one drive can use the cable at a time!
2 - Arguably, there is a small advantage due to a small cache on each drive. This cache is now typically 8MB. If you have a 4 disk RAID 0, this will give you about 32MB of cache. Of that, depending on the manufacturer, part is used for read and part for write caching. Let's say the manufacturer of the drive uses 1/2 for each (dumb algorithm.) This gives you about 16MB of really fast cache that you can do I/O to. For arguments sake, let's say that we are writing to the drive. The initial I/O of the first 16MB of data could transfer REALLY fast (for arguments sake, let's say full bandwidth.) Thus, with SATA-150 it will take about 107ms to write the first chunk of data. On a ATA-133 bus it will take 120ms, for a savings of 13ms. Now, don't go spending that all in one place! Since human reaction time is about 200ms, it is imposible for us to detect this time delta, thus, we watch cluelessly that our system has slowed by 13ms becuase we purchased ATA-133 instead of SATA-150.
That said...I am probably going to purchase a SATA drive...iff...the price is competitive with ATA-133! Why, because the cabling is so much nicer, there are no jumpers, and that is where the technology is headed. If you are going to SATA to get faster I/O, don't! Some time in the next few years it may make a difference, but not today. My advice is that SATA is a great option if the price is almost the same as you are paying for an ATA-133 drive. If not, wait for it to come down. The technology is better, but the performance is not.
Expecting various flames
The PuckMan
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