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Why Are Usb Disk On Modules So Expensive?


ascorbic
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I have been wanting to grab a USB Disk on Module for my ESXi server that I can boot the machine from and run ESXi from. My main motivation for this is to free up a SATA port.

For 8 gigs, it costs at least $100!

http://www.memorydepot.com/ssd/listcat.asp?catid=usbh

http://www.xpcgear.com/innodisk-deuf-08gu51c1.html (listed as discountinued)

I am tempted to just grab a regular 32 gig flash drive and hook it up to a USB connector that will stay inside of the case. I haven't been able to find a ten pin to usb header adapter, just the ones on a cable that mount externally, but if such a thing existed that would be more elegant. (aha! found it http://www.newegg.com/Product/Product.aspx...ECH-_-12200474)

But what are the embdedded ones so expensive? They seem so handy.

Edited by ascorbic
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http://www.memorydepot.com/details.asp?id=DOM2GUSB

The reason they are so expensive ?

Well, they aren't that much more expensive if you compare the price to other, physically much larger, SLC-flash-drives .

( As is usually the case, "miniature" does cost a bit extra ..)

Just an example, the "OCZ Rally 2 Turbo High Performance 8GB USB2.0 Dual Channel Flash Memory Drive"

will cost you about 120$ ..

Edited by IOSys
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If that small little sucker contained a SSD built into it, the high price would defenitely make sense.

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All flash drives, including the links to the ones I posted as well as the traditional USB plug in flash drives are SSDs.

Absolutely, windblows will treat them like any other HDD, allowing you to install and boot windblows from them .

A "normal" flash-drive won't let you do that because it behaves like "removable media" instead of a "fixed" or "local"

HDD .. However, most flash-drives can be made to appear as a "Fixed" HDD, using their "Mass-Production Tool"

The main difference between "normal", relatively cheap, flash-drives and these small "Disk-on-Module" (DoM)

devices is that almost all DoM's use Single Level Cell (SLC) NAND-RAM, giving you at least 10x more erase-cycles ..

MLC-flash is usually rated at 10k erase-cycles pr cell, as opposed to the guaranteed minimum of 100k erase-cycles for SLC-NAND-RAM. You can also get DoM's that will fit into a IDE-slot on your MoBo and there are also SATA-versions available ..

Edited by IOSys
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You can also get DoM's that will fit into a IDE-slot on your MoBo and there are also SATA-versions available ..

Yeah I see TONs of those types. But my motherboard DX58SO as phased out IDE ports. I also have plenty of extra USB ports so I would rather use one of those over my limited six SATA ports. I guess I am going to just spring the $100 for a 8 gig one.

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Forgive me if this question seems dumb ...

In the ESXi episode, Matt and Darren used a USB thumb drive/memory stick (call it what you will) to load the host OS and this was attached to the motherboard via a lead. I've been contemplating doing something similar and found this.

I'm not sure what the performance difference would be between a DoM and the methodology that Matt/Darren used. I understand that USB flash drives/memory sticks don't like repeated and frequent read/write operations. Is a DoM, in effect, a mini SSD mounted directly to a connector that can attach to USB, SATA or IDE on the motherboard?

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Forgive me if this question seems dumb ...

In the ESXi episode, Matt and Darren used a USB thumb drive/memory stick (call it what you will) to load the host OS and this was attached to the motherboard via a lead. I've been contemplating doing something similar and found this.

I'm not sure what the performance difference would be between a DoM and the methodology that Matt/Darren used. I understand that USB flash drives/memory sticks don't like repeated and frequent read/write operations. Is a DoM, in effect, a mini SSD mounted directly to a connector that can attach to USB, SATA or IDE on the motherboard?

Can you post a link and the time at which Matt and Darren do this? I am pretty sure I have seen the episode but my memory is hazy. I think what they did is they took a regular USB back plate and didn't screw it into the back of the case, they just let it hang inside.

The link to the product you posted is exactly the same as one I posted at the top of this thread. Using that versus Darrens method really isn't any different. It is just a bit more elegant because you don't have this wire dangling in there.

The biggest difference between the DOM versus the hacked internal USB flash drive would be what IOSys mentioned, this DOM are usually created to withstand a lot more writes. And I guess that is probably the answer to my question.

A DOM is just a flash/ssd based device that plugs directly into the motherboard.

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I sent memorydepot.com an email asking about these drives, how many erase cycles and if they use a wear leveling algorithm, I got a great response

The endurance: 2,000,000 Program/Erase Cycles

we do have a wear leveling algorithm,

It is explained on the attached specsheet, but don 't hesitate to contact me

if you have any additional questions.

Best regards

Fabien

Most plug them in usb drives have less erase cycles but I am having trouble finding specifications documents. Anyone have any concrete numbers? I tried to attach the PDF he sent me but it looks like the forums block it, let me know if you really woudl like to see it.

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All flash drives, including the links to the ones I posted as well as the traditional USB plug in flash drives are SSDs.

Sorry my bad, I just realized that after I finished reading your post. Don't know what I was thinking, must had my mind set somewhere else.

Edited by Infiltrator
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Theses numbers are from Samsungs own data-sheets, you can find the sheets

with Google by searching for the part-# :

SLC : Samsung OneNAND KFW4G16Q2M rated@ 100k erase-cycles

MLC : Samsung K9G8G08U0M rated@ 5-10k erase cycles

This is quite good for anyone wanting to know a bit more :

"Western Digital White Paper describing calculation and effects of SSD endurance"

http://www.wdc.com/WDProducts/SSD/whitepapers/en/NAND_Evolution_0812.pdf

Edited by IOSys
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