External SATA III (6GB/s) Enclosure and Sharing with PC

Hjiorst said:

If I got a SATA III PCI card, and a SATA III HD, rated at 6 GB/s, and put it into an enclosure designed a few years ago which only says it gets 3.0 GB/s, will I be limited to 3.0 GB/s?

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Yes. Although the bridge board in the case is acting more or less like a passthrough when using eSATA, that would be in the "less" rather than "more" category. I, for example, have a 6Gbit Hitachi drive in a Newer case that is 1.5Gbit, hooked to a port that supports 3Gbit speeds. It negotiates the connection at 1.5Gbit, since it's limited by the case. Depending on what, exactly, the bridge board in the case is doing, it could actually slow it down further--not sure about that, though.

That said, unless you're using SSDs (and good ones, at that), it won't matter.

1.5Gbit/s SATA equates to about 150MB/s at absolute maximum (there's overhead eating up the other two bits per byte). A fast 7K rotating drive can read data at a max of around 152MB/s, meaning that even at 1.5Gbit SATA speeds the drive is operating at nearly full speed with the exception of cached reads (which won't help at all with large-file throughput). A more wallet (and power) friendly 5K drive is going to max out at under 120MB/s, so it's not going to see any real speed boost at all, regardless of what kind of SATA bus it's attached to--it can't saturate any of them.

Good modern SSDs can more or less saturate a 6Gbit SATAIII bus (500-550MB/s), at the cost of vastly reduced storage capacity and vastly increased price, of course, but that's kind of ridiculous for anything other than a boot drive or high-end video capture, where massive throughput is necessary and cost is no object.

Frankly, though, for most purposes 3G SATA is plenty fast for any rotating drive for the foreseeable future. And if it's an Expresscard, the speed of the bus is going to limit throughput to not much faster than 300MB/s speeds anyway.

Hjiorst said:

Second question: Will I be able to switch said eSATA hard drive between my Mac and a PC running XP?

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Yes, with the caveat that if you use FAT32 it's going to hamstring performance. The MacOS in my experience is somewhat slow writing to FAT volumes, and it's a pretty shoddy filesystem in general. ExFAT might work better, and both the MacOS and XP can use it if they're up to date; no personal experience with that, though.

The conflicting information you read is probably because some are assuming no additional drivers. Out of the box, the MacOS can read and write FAT, but only read NTFS. Windows can read and write both, but can't do anything at all with HFS. Further, XP 32 bit doesn't understand disks formatted using the GUID partition table (GPT), regardless of the formats of the partitions on it (XP x64 and all later versions of Windows are ok with GUID disks). All versions of Windows understand MBR, and none, out of the box, understand Apple Partition Map (APM). The MacOS has been fine with all three for a while, although MBR is generally only used for FAT disks, and GUID is the preferred type for any Intel-based Mac; APM disks are no longer necessary for anything other than booting an old PPC Mac.

Keep in mind here that any of the three types of partition maps can technically contain partitions formatted in any of the available filesystems, although many of the weirder combinations are pointless.

There are, however, a couple of 3rd party drivers that add NTFS write support to the MacOS. Alternately, MacDrive is supposed to add HFS read and write support to Windows (I believe it also adds the ability to understand APM drives). MacDrive and one of the available Mac NTFS drivers are paid software, but there's a free trial of MacDrive and some of the NTFS write drivers are free.

Which of the three is best for you will depend partly on what you want (or need) to do, and which OS you use most. FAT is the "easy" one out of the box, if you don't mind that you can't create files bigger than 4GB and the limited features (in both OSes) of it. Many people prefer an NTFS write driver on the Mac, while I personally would probably spring for MacDrive so I could use HFS and have it work the most smoothly on the Mac, at the cost of only working out of the box with my Windows install.


Final note: I'm not necessarily recommending this (I didn't buy one for my MBP, opting for eSATA instead), but Caldigit does make a USB 3.0 Expresscard and PCIe card that have Mac drivers and claim full compatibility with USB3 devices (unlike LaCie's "USB3" products, which ONLY work with their own USB3 enclosures on the Mac).

Hjiorst said:

But this does confuse me slightly: Why does anyone make a 6GB Hard Drive if it can't actually read or write from the disc anywhere near that speed? I've seen plenty of 3 GB/s and 6 GB/s hard drives (not solid state; disc drives) being offered. What good are they?

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Part of it is, presumably, just for marketing purposes. In real terms, though, when the drive is hitting its RAM cache, it will be able to write (or sometimes read) data much faster than it can off the disk; this is limited to 32-64MB (depending on drive), but does mean that for short bursts of data the drive can take advantage of the higher bus speeds, which in some cases will result in a small performance increase.

Of more significance are port-multiplier enclosures, which allow you to hook multiple drives to a single (compatible) SATA channel. In that case, a 4-drive RAID0 array could transfer data at 600MB/s (theoretical), in which case the difference between SATAII and SATAIII is substantial. Edge case only of interest to media pros, but real.


I assume you're interested in faster 7K disks, but if you don't mind the modest decrease in speed (with corresponding decrease in noise and power consumption), you can get a 3TB 5K drive for about $120 if you watch for sales.

And you can always find someone with horror stories about any drive manufacturer, but Hitachi has basically been okay since the IBM Deathstar debacle way back when. I've been happy enough with the 5K3000 in my server.

I will note that I personally prefer to stick to drives with 3 or less platters--that seems to be the sweet spot of speed, reliability, noise, and heat in my inexpert opinion--and at this point 3TB drives with only 3 platters are just starting to hit the market, although a lot of new 2TB drives are 3 platter. You'll also get somewhat (or significantly) better max throughput on a 3-platter drive than an equivalent-sized 4 or 5 platter one, due to better areal density.

Getting the Most out of My OWC

Nice info, Makosuke!

So how about a 120GB OWC Mercury Extreme Pro 6G SSD connected to a StarTech 2 Port SATA 6 Gbps ExpressCard 2 eSATA Controller Card plugged into a Dell Precision M6300 (all hooked up using proper 'cableage' to fully support SATA III throughput, of course)? This is outside of any enclosure which could limit throughput, using just the SATA III cable and an IDE/SATA power adapter from USBGeek.

I realize there was no reference to anything "Apple" in this post, but I stumbled upon this thread via the Googleways, and your post alone amongst all else I have read on the net most directly and succinctly answered many questions I had surrounding how to get the most out of my SSD purchase.

Thanks for any feedback in advance,

-Tony

ajbufort said:

So how about a 120GB OWC Mercury Extreme Pro 6G SSD connected to a StarTech 2 Port SATA 6 Gbps ExpressCard 2 eSATA Controller Card plugged into a Dell Precision M6300 (all hooked up using proper 'cableage' to fully support SATA III throughput, of course)? This is outside of any enclosure which could limit throughput, using just the SATA III cable and an IDE/SATA power adapter from USBGeek.

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Yes, that should work just fine, although it will look rather funky just sitting there flopping around in the open.

I have that exact OWC drive in my laptop at home, and have absolutely no complaints, even running at 3G speeds. With the nice blue case, it even looks pretty good bare. I really like OWC's hardware, and trust their support as well--the couple of times I've dealt with them, they've been very helpful, and when they upgraded the warranty to 5 years from 3 they retroactively gave everyone who'd already bought it the upgrade. They also are very serious about being "green"--they built a big wind turbine out front of their warehouse to power their operations.

One thing to keep in mind, though, is that you will NOT be getting the full 500MB/s+ speeds that the SSD is capable of. The Expresscard interface is limited to about 250MB/s throughput, so at best you'll see about 3G SATA speeds, no matter what you do. Unless you want the 5 year warranty, you might consider the cheaper Electra, since it's only a tiny bit slower than the Extreme Pro and you won't see that difference at all in practice on that setup.

There is no way around that on a laptop, unless you have a USB3 port on the laptop itself and a USB3 case for the drive that is actually capable of >250MB/s throughput, which I've read many are not, or you get a laptop with a Thunderbolt port and a compatible case (which are currently almost nonexistent).

Hey Makosuke,

Once again, thank you for a very informative (and prompt) reply. Much appreciated!

As I read through your response, I went from "Hooray!" to a bit of a let down. I was working hard to get all the juice I could out of this baby, despite all the potential pitfalls, and it looks like I still choked, though in the end I am not too surprised. I knew that my ExpressCard knowledge was the weak part of the equation.

Your answer was clear, though I remain confused and dubious concerning one thing - the limitations of ExpressCard, both in general terms and in terms of what my Dell has on it. After extensive research on the net, it seems that MANY folks are confused about what they have on their machine, as well as just what it can do if they do have it. I refer in particular to the efforts to determine whether someone has a 1.0 or 2.0 interface on their hands, as well as the max possible throughput. Apparently, consultation of manuals, support, and Internet research isn't always enough.

When you said the interface "is limited to about 250MB/s throughput," I presume you were referring to the 1.0 spec. I am seeing these numbers in many places on the net:

ExpressCard 1.0 : Up-to 2,5 Gbit/sec
ExpressCard 2.0 : Up-to 5 Gbit/sec (released in March 2009)

...so despite any info to the contrary, I am inclined to believe these numbers. If this is true, and my Dell has 2.0 capability, then I won't fall too far short of SATA III max capability. I was hoping to achieve buss parity between my laptop and the drive, and not over-saturation on the laptop side, but it looks like that's not destined to happen. As you said, there ain't much more I can do at this point. But at least I can hope I'm at 2.0 instead of 1.0.

AND I can take some comfort in the fact that I still have an excellent product which I can use at reasonably fast speeds and, in the future, hopefully I can somehow take full advantage of its capabilities.

Your mistake is that the Expresscard 2.0 standard was announced in 2009; the official announcement at that time mentioned toward the bottom that actual products were expected some time in 2010 (late 2010, apparently). At the least, as of the end of 2010, nothing was on the market at all.

I have seen absolutely nothing mentioning Expresscard 2.0 compatibility since then, and there is no mention of it on the Expresscard official site apart from the 2009 announcement of the new spec--no "now shipping" PR, no explanation of increased speeds, no "how to tell the difference," etc.

Apparently the current Sandy Bridge chipset is capable of supporting it, which I base on the fact that SeriTek has an Expresscard 6G adapter that has been clocked at 380MB/s on the current-generation MacBook Pro that I have, which would require an Expresscard 2.0 slot. Whether all Sandy Bridge-based Expresscard slots are 2.0 or not, I'm not sure. (Expresscard 2.0 supports USB3 in place of USB2, and since Sandy Bridge currently has no built-in USB3, it's possible that the slots support 5Gbit speeds but can't technically be advertised as Expresscard 2.0 since they don't include the USB3 part of the spec.)

Certainly, your laptop's manual doesn't say anything about the slot being 2.0. If it's Sandy Bridge based, it's possible that, like mine, it supports 5Gbit speeds and just can't be advertised as 2.0 due to lack of USB3. In which case, assuming that StarTech card supports the higher throughput (which it probably does, since it's advertising 6G), you'd get max throughput up in the 400MB+ range.

Bottom line here being, it's certainly possible that you'll get better speed, but it's not guaranteed. I'd love to hear a benchmark number from you if you do decide to try this out.

Hey Makosuke,

I'll be more than happy to post progress reports and findings, starting now.

The SATA III ExpressCard attempt succeeded in crashing my Dell to the point that I had to go to my company's Laptop Service Center to "flatten and reload" my machine. Thankfully, I'm back up to speed, and I was about to abandon the effort, when I gave it one more try. Very risky of me, I know, but I'm a stubborn dev, and therefore, don't like to go down and admit defeat easily.

Bottom line: it now works!

The roots of my problems were:

(1) Attempting to switch from ATA to AHCI in my bios. I was able to reboot a few times after that, but no more. I was fiddling with various versions of Marvell drivers while doing this, so there you go. I was NOT aware at the time that this is a very bad thing to do which will almost certainly result in BSODs and systems stuck in repair mode forever, which was exactly what happened to me!

(2) Failure to realize that, while not in AHCI mode, both the controller card and the drive are NOT hot-swappable! I was inserting and removing all the while with my machine still on. Bad idea!

So after learning these hard-won lessons, I had the balls to try again, only this time I did the following:

(1) Turn off machine.
(2) Insert SATA III ExpressCard
(3) Boot machine
(4) Go to Manage Computer, see that driver not installed
(5) Update driver with included CD (do NOT get fancy and try to get a more recent version of the driver)
(6) Confirm that update worked in Device Manager
(7) Turn off machine
(8) Hook up SSD drive to the ExpressCard
(9) Boot machine
(10) Confirm that Windows recognizes the drive upon startup and auto-loads the correct driver to make it visible under "My Computer"

And there you go.

For the record, the driver that came on the CD was:

Marvell 91xx
1.0.0.1034
12/25/2009

I know there are later ones, but unless I am convinced there is a VERY good reason to attempt it, I'm sticking with what works and what was supplied by default at this point!

I then proceeded to confirm that Defrag and ReadyBoost were disabled for that drive. They were. Defrag does not offer this drive as an option in the scheduler, and ReadyBoost is off. Have yet to check on the status of Superfetch.

I then executed a benchmark test with ATTO. Attached is a screen clip of the results.

NOTE that I am NOT using a SATA III-compliant cable at the moment. What I am using is only rated at 3Gbps SATA II. Going by the numbers, however, it doesn't look like it much matters. I am not pushing the 3Gb boundary, but it does look like I am getting somewhere between 1.5 and 2.0. I would likely be disappointed at this point, but after all I've been through, I'm taking it as a victory.

Is it possible I am not hitting more around the 2.5 mark because I am in ATA mode? If so, then that's tough toenails for me, because switching modes is out, and I am NOT about to attempt the registry hack I've seen touted for switching modes without a reinstall.

Update

So to give an update on my situation, after I made that previous "success" post, I shut down and then later rebooted, and much to my chagrin, my drive was no longer recognized. Attempting to get rid of everything and repeat the process I cited as being successful earlier did not work either. SO...

I did more research and came to realize that Marvell does not have a very good reputation concerning its drivers. I experimented with various versions, and finally went to Startech support and asked them for help. They gave me a driver which was neither included on the CD supplied with the controller card, nor which I was able to see as being readily available on the net.

THIS driver worked, thank God!

The version was 1.0.0.1051, dated 11/22/2010. I tested for durability by rebooting, and the drive was still recognized. Whew!

Did another benchmark with ATTO, and got the same results I did the last time. I am happy to have speeds well past USB 2.0-land, but I sure would have liked to get this baby up to the 250MB/sec ceiling for the ExpressCard 1.0 spec. Like I said, I am not willing/able to go into AHCI mode, and I am not even sure that would make such a big difference given all that I have read - NCQ being of questionable benefit to SSDs and all.

So I am stable now, but no faster than before.

I am going to experiment with a USB 3.0 ExpressCard and USB3-to-SATA cable to see what I get under those conditions, though I am not optimistic that I will exceed or even meet the speeds I have attained so far.

For readers' benefit, I have attached the archive provided to me by Startech. There is an installer, which is nice, so manual driver install need not be done. (Not even sure manual install would work. I have read about some funky things going on with the Marvell stuff.)

Also attached is a screen clip of what my Device Manager looks like now.

I was away from my computer for a week, but wanted to mention that while AHCI mode may not help at all with the top speed of the drive (or, who knows, maybe it will--I'm not sure), it is possible to switch Windows on the fly. I ran into this after accidentally installing a clean copy of Win7 Enterprise on a freshly built machine at work before realizing that the driver defaulted to ATA mode on the SATA ports.

You can find instructions without too much difficulty, but the issue you were seeing is caused by the fact that Win7 does not, by default, install AHCI drivers for itself if it was originally installed on an ATA disk. The trick to fixing it essentially involves using a registry edit to get Win7 to download the drivers and install them prior to swapping the setting in the BIOS, at which point it should (and did in my case) boot fine.

Of course, things like this are the reason I'm posting these comments on a Mac forum, and only have to deal with Windows and BIOS issues (the MacOS uses EFI) at work.

A bit of an addendum in terms of speed, I was, until a few days ago, running my OWC 6G drive on a 3G port due to a firmware issue limiting speeds that got fixed in a recent update. It's now at 6Gbit, and indeed, I have benchmarked it at throughputs well above 400MB/s, around 480MB/s in some cases. That is some serious speed.