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Drive Holes/Breather Ports & HDD cooling

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July 27, 2009 2:48:53 AM

I've known about the tiny "drive holes" (sometimes called "breather ports") on internal hard drives and the warning against covering or obstructing them for years, but it was never an issue for me in the past since I always installed these drives inside my computer cases (as almost everyone does). Installing them that way made the warning moot, since computer cases are designed to provide ample room below/above each internal drive.

But now I have so many unmounted internal SATA drives that I can't install them all inside my computers' cases, and in any case I need to be able to arbitrarily switch them around and connect and disconnect them directly to my various computers' mobos at will.

I do this primarily (but not only) for backup purposes on my several XP Pro boxes: Using Acronis Disk Director 10, I can make an exact, bit-for-bit duplicate of a 1 TB hard drive (or any individual partitions on it) to another drive or another partition on the same drive in 10 minutes or less! That capability has, as one might expect, dramatically increased my willingness to back up my data on a daily basis, something that is particularly important because I use RAID 0 (striping) arrays quite a lot, which, although risky, increases the transfer rates and related disk speed attributes considerably.

But DD 10 allows that level of speed only if I connect the backup drive directly to a mobo's internal SATA port(s). I've long since given up on external drive enclosures because the intermediary USB, Firewire, or even eSATA interfaces dramatically slows down access and increases the DD 10 backup time from minutes to hours or even days in extreme instances! This is an empirical observation given the products I own; I understand that the theoretical speed of these various interfaces -- especially eSATA -- shouldn't cause such a severe reduction in speed. (One reason for the slow-down relates to the device drivers involved; If you're able to use the "Safe Mode" (an inapt name) of DD 10, the speeds are incredibly high, but Safe Mode pretty much only works with the lowest-level (and hence essentially driverless) disk-to-disk I/O mode. If you're copying / backing-up to external drives or drives with an extra layer of interface between the internally-connected hard disk and the backup device, you often need to use DD 10's "Full Mode", which is usually much slower because it needs to employ device drivers for the I/O).

With that background laid out, I can finally get to my questions:

(1): What is the minimum clearance I must allow so as not to obstruct the drive holes/breather ports? I have a small workspace and so I've been placing the drives either directly on the desk or stacked right on top of each other. It finally dawned on my tiny little mind that this is probably a bad idea.

(2): What is the purpose of these drive holes? My guess is that they're necessary to equalize the internal and external air pressure (such as would be caused by the drive changing temperature relative to the ambient room temperature) rather than to cool the drives per se, due to the sensitivity of the airflow for maintaining the flying height of the heads, but I could be wrong about that so I need to know the facts.

(3): Is dust an issue for these drive holes? I started working with hard disk drives and magnetic drum storage early on (mid 70's), and I've seen the classic diagram of the enormous relative size of dust particles compared to head-to-platter distances (which have only gotten shorter over time) several hundred times in those days (the only copy of the diagram I could find online in a short span of time was in .tdk media format, and the only player I could find runs only under 16-bit versions of Windows, which isn't available as an option even under XP Pro's compatibility modes...) The room these drives are in is rather dusty; how concerned should I be?

(4): How big an issue is drive cooling under these circumstances? My hunch is that the greatest overheating risk associated with internal hard drives comes from the fact that they're usually installed inside computer cases, and so their proximity to the power supply, CPU, and motherboard substantially increases the operating temperatures of the internally mounted hard drives (the only Click of Death or other fatal hard drive failures I've personally encountered were on drives that were mounted inside a case.) Therefore, it seems to me that since the drives I'm talking about are not inside any cases, I needn't be concerned at all about providing cooling fans or whatnot as long as the ambient temperature in the room stays within a human-comfortable range. Am I right about that?

If I need to provide additional cooling for these unmounted drives, I have few good and affordable options. I tried the Sans Digital HDDRACK5, but as the review on that page indicates, it's too poor a design to accommodate my needs, especially considering how often I swap drives around (which resulted more than once with literal drive crashes when one drive collapsed onto another due to the product's poor design).

The only other option that looks promising is the Ziotek Hard Drive Gasket (here's a YouTube video demonstration). But it provides only passive cooling, which would be no better (and might be worse) than what I'm doing now. There's one principal advantage, though: It wouldn't obstruct any drive holes (assuming I'm obstructing them now).

Thoughts, anyone?
a b G Storage
July 27, 2009 7:41:18 AM

Basically, the closer your hard disks are to each other, more each other's heat will contribute to the other oneā€”and the overall heat problem of your desktop.

Regarding clearance, it's best to look at how your hard disks are laid out on your case... it's a good guide of what kind of spatial configuration you need to create to keep your hard disks running properly.
a c 415 G Storage
July 27, 2009 7:52:39 AM

As you surmised the breather holes are there to equalize air pressure. The issue is that if the ambient pressure changes (high pressure vs. low pressure weather systems, or the drive is used by someone living on the top of a mountain) then the unequal pressure could potentially apply forces to the case which would affect the alignment of the precision mechanism, or it could allow unfiltered air to seep in around the case gasket (the breather hole itself has a filter to trap dust or a flexible plastic membrane which actually keeps outside air from getting in).

I wouldn't worry about dusty rooms as the breather hole is designed to protect the clean environment within.

Air finds its way through awfully small crevices and so I wouldn't worry unduly about obstructing the breather holes. If you're really paranoid you could perhaps put some cardboard shims between stacked drives to keep a fraction of a millimeter between them (but see the next paragraph...)

Rather than obstructing the air hole, the larger problem of stacking drives on top of each other is overheating. If you have three drives just sitting on top of each other, the middle one is going to not only have hardly anywhere to dissipate it's heat, it will also be having to cope with the heat of the drives above and below it.

Temperatures for standard drives (up to 7200 RPM) shouldn't be a problem as long as you allow an inch or two around the drive for air convection to carry the heat away. But 3.5" server drives that run at 10,000 or 15,000 RPM are sometimes intended for use in carriers which act as thermal sinks - those may require a bit more care.
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July 27, 2009 3:25:19 PM

Thanks, sminlal and r_manic.

For the record, I stopped stacking the drives directly on top of each other some time back. I inserted spacers (mostly empty plastic RAM packages which are flat and narrow) between them. But I did that in order to keep the drive holes clear rather than to keep the drives cool, so I thank you both for letting me know that the drive-to-drive heat transfer is what really matters, not the drive hole clearance (which as you point out, isn't important unless I wrapped the drives in plastic shrink wrap or some other equally stupid idea that would seriously obstruct the holes).

sminlal said:
Temperatures for standard drives (up to 7200 RPM) shouldn't be a problem as long as you allow an inch or two around the drive for air convection to carry the heat away. But 3.5" server drives that run at 10,000 or 15,000 RPM are sometimes intended for use in carriers which act as thermal sinks - those may require a bit more care.
So you'd agree that using the very cheap Ziotek Hard Drive Gasket for each drive would be fine for me because I could then stack the gasketed drives on my desk without worrying about providing additional cooling (especially now that I know the drive hole issue isn't a problem after all)? I ask because the people who replied to that YouTube video demonstrating their use cited inadequate cooling as the reason they didn't like the product. So they were simply off base with those comments, right?

Also, I do have a couple 15K RPM drives, but they're among those that I installed internally in a computer case.

a c 415 G Storage
July 27, 2009 8:53:45 PM

ambush said:
So you'd agree that using the very cheap Ziotek Hard Drive Gasket for each drive would be fine for me because I could then stack the gasketed drives on my desk without worrying about providing additional cooling (especially now that I know the drive hole issue isn't a problem after all)? I ask because the people who replied to that YouTube video demonstrating their use cited inadequate cooling as the reason they didn't like the product. So they were simply off base with those comments, right?
No, I'd be concerned about cooling with those as well, in particular if you tried to run them when they were stacked. It seems to me that the silicone would tend to act as an insulator - a bad thing when the drive is trying to dissipate heat (think of it like wearing a winter jacket on a hot summer day). Again, for heat dissipation you need to either expose the drives to air that's either moved via a fan or has enough space to move by convection, or secure them to a metal bracket which will carry the heat away to somewhere else.

I could be wrong about the thermal properties of silicone, but my wife has silicone oven mitts which tells me it's an insulator and not a conductor of heat.

It looks to me like those gadgets are primarily designed for reducing shock to the drives during storage or transport, but I'd be skeptical of actually running the drives in them...
July 28, 2009 2:02:40 AM

sminlal said:
... It looks to me like those gadgets are primarily designed for reducing shock to the drives during storage or transport, but I'd be skeptical of actually running the drives in them...
I'm glad I asked! Thanks again.
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