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Old 02-03-2012, 07:05 AM   #1
LinuxNoobX
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Question End-User RAM Disk Laptop


If you know what the subject line is referring to you probably already know what questions I am going to ask.

I did a Google search and it seems that any RAM Disk computers in existence do not come in the laptop variety and if they do there is no chance I am getting my hands on one right now.

But I still have a Linux-related question. Let's suppose my Laptop had in the area of 30 GB of RAM. What special modifications need to be made (hardware and software) for me to run Linux off the RAM? Z/Z
 
Old 02-03-2012, 12:07 PM   #2
theNbomr
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You may be confused about the terminology you are using. RAM is volatile memory, unless backed by uninterruptible power. A RAM disk is a data structure which an OS can use as part of a filesystem. Storing files to a RAM disk does not create a permanent record of the files. When power is removed or the computer reboots, the RAM disk contents are lost.
Perhaps you are referring to Solid State Disks, which are memory-based storage used in the same way as spinning magnetic drives. These are not RAM, however; they are flash memory, which is a completely different memory technology that is non-volatile.
In answer to your last question, I think you need to be a little more clear. There is a significant distinction between 'running' and 'booting'. You can never boot a system from a RAM disk. However, a RAM disk image can be loaded from a conventional disk by a bootloader, and the system can run perfectly well from that RAM disk. You don't need anything like 30GB of RAM to make that happen.
Most Linux distributions use an initial RAM disk (initrd) as part of the bootstrap process. The bootloader loads the kernel and initrd into RAM, and then passes control to the kernel. The kernel uses the contents of the RAM disk to progressively initialize more drivers and gain access to more hardware, such as conventional spinning media filesystems.

--- rod.
 
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Old 02-03-2012, 12:52 PM   #3
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Awesome. I was reading an entry on wikipedia about a technology called RAM disk but as you said RAM is volatile and a reboot or unexpected crash would thrash a system based on it. I was interested in the topic because RAM's data transfer rate is MUCH higher than a hard disk.

If I had thought about it a bit moar I would have realized the possibility that a live 3.0 usb Linux distro may run faster than a hard disk and be stable ( I need to do moar research to confirm or deny this ).

In any case:

1. Does solid state technology have a faster transfer rate than RAM and

2. Is there an easy way to incorporate solid state technology into a portable device such as a laptop or is it already available?

In most cases I do like to do my own research but when it comes to the viability of newer technologies I like getting qualitative analysis from experts in the field as opposed to company PR men who just want to peddle their product. Z/Z
 
Old 02-03-2012, 01:56 PM   #4
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A USB Flash drive would be on the same order of speed as a Solid State Disk (SSD), but capacity is generally much lower. SSDs are now commodity items, and are available in desktop and laptop form factors.

In general, RAM is much faster than SSDs, and SSDs are faster than spinning magnetic media. SSDs show more performance gain over magnetic disks for reading than they do for writing.

--- rod.
 
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Old 02-03-2012, 02:05 PM   #5
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I am thankful you took the time to inform me about how to improve upon my hardware. Have a great weekend. Z/Z
 
Old 02-03-2012, 02:49 PM   #6
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Quote:
Originally Posted by theNbomr View Post
A USB Flash drive would be on the same order of speed as a Solid State Disk (SSD), but capacity is generally much lower. SSDs are now commodity items, and are available in desktop and laptop form factors.

In general, RAM is much faster than SSDs, and SSDs are faster than spinning magnetic media. SSDs show more performance gain over magnetic disks for reading than they do for writing.

--- rod.
I have never seen a USB flash drive that could approach the speed of a good SSD.


As for speeds, you're looking at (VERY BALLPARK)
USB flash drives - 10-100 MB/s
platter drives - 50-100 MB/s
SSD - 100-500 MB/s
RAM - 1+ GB/s

Last edited by suicidaleggroll; 02-03-2012 at 02:50 PM.
 
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Old 02-03-2012, 03:22 PM   #7
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Thanks for the breakdown. The new USB 3.0 standard supposedly has transfer rates approaching 5.0 Gbits/sec which is over 10 times the 2.0 currently popular. 3.0 has not gained wide popularity yet and there is speculation about whether it will catch on. I am not positive but from a cost perspective getting a 3.0 flash drive (with a high capacity) and a laptop with a 3.0 port may be significantly cheaper than a Lappy with solid state technology.

Even if the 3.0 transfer is slower than solid state it will probably be much faster that a hard disk. One advantage using 3.0 technology would have over solid state is extreme portability ( by which I mean easy to transport ) and of course would have the advantage that all USB flash drives enjoy in that entire back-ups can more easily be made and implemented in the situation that the primary machine dies.

I like versatility. It is all speculation at the moment until the future of USB 3.0 is determined. The needs of the Linux professional ultimately dictate which technology they will use of course.

I know a guy whose personal machine is so pimped out it is moar Tokyo drift racer than desktop... it requires moar than two men to move it around. I personally prefer mobility for situations such as assisting a friend with tech issues that require me to be away from home.

Imma do some moar research before I decide on the hardware I want. Thanks for the input. Z/Z
 
Old 02-03-2012, 03:31 PM   #8
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Quote:
Originally Posted by LinuxNoobX View Post
Thanks for the breakdown. The new USB 3.0 standard supposedly has transfer rates approaching 5.0 Gbits/sec which is over 10 times the 2.0 currently popular.
It can support 5Gb/s transfers, that doesn't mean anything on the market can actually do it. It's a very important distinction. Many hard drive manufacturers are making their platter drives conform to SATA-III specs, which can support 6Gb/s transfers, but they're still the same old crappy platter drives with 80MB/s read/write speeds. The speed that the interface is capable of handling has no impact on the speeds you'll actually see, as long as it's high enough to not slow things down.

The speeds quoted above are for USB 3.0 flash drives. The absolute fastest ones on the market are roughly the speed of platters.

You should be very weary of using flash drives for an OS as well, you will wear out the cells in no time flat with the constant reads/writes that an OS does on the drive. Solid state drives suffer from the same problem, HOWEVER most new SSDs, and all Linux kernels above 2.6.33 support TRIM, which is a form of wear-leveling to prolong the life of the flash cells in the drive by distributing the writes across the entire disk before going back and re-writing to the same cells. Without any form of wear leveling (which USB flash drives don't have, AFAIK), the constant reads/writes performed by an OS will wear out the the flash cells very quickly.

Last edited by suicidaleggroll; 02-03-2012 at 03:33 PM.
 
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Old 02-03-2012, 03:44 PM   #9
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That's a very persuasive case for solid state. Do you mind me asking for a ball park quote for a decent solid state laptop and a reputable vendor ( highly doubtful there is a merchant that carries quality merchandise like that out here in the sticks ) ? I try to stick to low-mid level gear in terms of cost primarily because it mitigates losses in the event a machine is damaged while working away from home. Z/Z
 
Old 02-03-2012, 03:59 PM   #10
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Most computer manufacturers cheap out on the drive, especially SSDs. When it comes to laptops, I prefer to customize them with the cheapest drive available and then purchase the SSD separately and install it after-the-fact (same goes for RAM actually). I'm a fan of Intel drives, but there are several good manufacturers. I just built a desktop machine about a month ago with an Intel SSDSC2MH120A2K5 for the boot drive. The drive is spec'ed at 210 MB/s write and 450 MB/s read on SATA-III, I tested it at 218 and 438. It retails at $280 for 120 GB though, which is a little pricey.

As far as laptop vendors go, I don't really have a favorite. As long as it uses a standard 2.5" SATA drive, you should be able to swap in just about any aftermarket SSD. A few years ago there were issues with laptop bios's that wouldn't support SSD, but I think that's all in the past by now. It wouldn't hurt to do some Googling on whatever laptop you choose though before going through with it.
 
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Old 02-03-2012, 04:12 PM   #11
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That is much more affordable than I had expected. I still have to do some research on other aspects of hardware performance such as bus speeds so I don't dump too much money into a machine that is going to bottleneck. I am recording your posts for future reference. It is kind of you to share your expertise. Have a great weekend. Z/Z
 
Old 02-04-2012, 07:25 AM   #12
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Quote:
Originally Posted by theNbomr View Post
You may be confused about the terminology you are using. RAM is volatile memory, unless backed by uninterruptible power. A RAM disk is a data structure which an OS can use as part of a filesystem. Storing files to a RAM disk does not create a permanent record of the files. When power is removed or the computer reboots, the RAM disk contents are lost.
LinuxNoobX actually sort of had the terminology right, even though you are right as well on RAM being volatile. The whole 'RAM disc' term gets a bit fuzzy once you start really looking at it. From the 'Let's suppose my Laptop had in the area of 30 GB of RAM. What special modifications need to be made (hardware and software) for me to run Linux off the RAM?' question, what LinuxNoobX is actually thinking about a 'virtual' RAM drive, not a 'hardware' RAM drive. (BTW, a virtual RAM drive is do-able with linux).

As far as hardware RAM drives go, theres been a few over the years, the only company still making them AFAIK is hyperOS-

http://www.hyperossystems.co.uk/07042003/index.htm

They get around the volatility problem with a battery (limited lifespan before the charge goes out) and an external power brick.

You could get an external eSATA 5.25'' enclosure, shove the hyperdrive + RAM sticks into it and run it with a laptop, but its not worth it. The HyperOS setup uses DDR2/SATAII, so its limited to 300MB/sec, you can get cheaper and faster with SATAIII SSDs. Some of the other hardware RAM disc setups (eg gigabyte iRAM) is even worse, they have SATAI (1.5Gbit/sec, 150MB/sec) connectors and use DDR1 (which isnt really a problem, DDR1 400/3200 is faster than SATAI, but its more expensive per GB and harder to get in big capacity sticks)

BTW, for some users, hyperOS could be worth it. I'd love to get my hands on one for a friend of mine who does 3D work, and its not unusual for him to use 100% of his RAM, + some swap, for a week+ at a time. It would be a nice experiment to see if installing a hyperdrive III/4/5, and set it up as his swap partition would increase the rendering rate.

Quote:
Originally Posted by suicidaleggroll View Post
It can support 5Gb/s transfers, that doesn't mean anything on the market can actually do it. It's a very important distinction. Many hard drive manufacturers are making their platter drives conform to SATA-III specs, which can support 6Gb/s transfers, but they're still the same old crappy platter drives with 80MB/s read/write speeds. The speed that the interface is capable of handling has no impact on the speeds you'll actually see, as long as it's high enough to not slow things down.
Its not that bad, the HDDs have got faster over the years. Depending on which benchmark you want to use, and the position in the platters, 150MB/sec is possible from the newest, fastest platter HDDs.

Not that fast compared to a SSD though, and thats just the transfer rates, SSDs have even more of an advantage over HDDs for access times.

Quote:
Originally Posted by suicidaleggroll View Post
The speeds quoted above are for USB 3.0 flash drives. The absolute fastest ones on the market are roughly the speed of platters.
Not anymore. Sandforce USB 3.0 drives are out, now.

http://www.everythingusb.com/super-t...ive-21182.html
 
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Old 02-04-2012, 07:56 AM   #13
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Wink

@me Drools...

When I woke from my technology-induced coma I was going to thank you for showing me a magnificent piece of hardware. Then I saw the price tag and saw the shenanigans you were up to.

How stupid do you think I am? I have seen 256 MB 2.0 Flash drives go for moar than that amazing 50 GB 3.0 Flash Drive. You should not be hosting bogus websites to falsely raise the hopes of technology addicts... it is hurtful and cruel. Aluminum casing... we all know manufacturers are too cheap to spend a nickel on non-synthetic materials.

You are a bad bad man

Kidding aside... have you taken it for a test drive? I'll take the word of a pro over a company press release any day. Z/Z
 
Old 02-04-2012, 09:58 AM   #14
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Talking about RAMDisk: HOW-TO: New and Improved RAMboot for speed and silence All you really need is the RAM memory that you already have !

Regards
 
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Old 02-04-2012, 10:23 AM   #15
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OMG! This is why I love hackers. They make MacGyver look like an amateur. Not saying I wouldn't use the 3.0 method or the solid state method but being able to drastically improve computer performance on the fly is an amazing skill to possess.

Looks like Debian will be on the menu in the near future. Thanks ukiuki Z/Z

Random Quote (unknown origin): "If it aint broke you aint trying" Z/Z
 
  


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