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- Price, for one. FLASH RAM in large quantities is more expensive. - Density/space for another. Hard drives store data more densely than RAM. 35GB disks not so much, but consider the 140 and 300GB disks in the iSeries or the 750GB disks for PCs. Adding that much RAM will take a lot more space. - Heat and power. You might not realize it, but the power consumption and subsequent heat generation of RAM can be greater than disk. I'm not too sure about this one; it may be a wash in the end. - Speed is a tradeoff. FLASH RAM isn't nearly as fast as normal system RAM and modern 10 & 15K hard disks have higher sustained transfer rates than FLASH. FLASH will be much better at 'seeks' or random I/O, though. The CF card I link to below can sustain 20MB/s transfer; modern hard drives can do 60-80+MB/s. - Reliability. Believe it or not, FLASH RAM isn't really that reliable. This can be mitigated with ECC technologies and other things, but those will add to cost, space, heat/power, and may reduce speed. FLASH RAM is also generally limited in the number of writes it can sustain before it wears out (reads AFAIK are unlimited). This is in the thousands if not millions, but there is generally a limit. All of that said, RAM-based computing can be yours if you have deep pockets. At least for a PC. There are several products out there that use either normal RAM with a battery backup (normally good for no more than a day or so of no power) or FLASH RAM to mimic a hard drive. They are comparatively pricey, though, and are still oriented towards specific computing environments where hard drives aren't suitable (ex: solid state is necessary due to vibration). 750GB 7200RPM hard drive: $345 and up: http://www.pricegrabber.com/p__Seagate_Barracuda_7200_10_750GB_Hard_Driv e,__19215475 146GB 15K RPM hard drive: $500 and up: http://www.pricegrabber.com/search_getprod.php/masterid=6335759 8GB Compact FLASH RAM: $335 and up: http://www.pricegrabber.com/p__Lexar_8GB_CompactFlash_Card,__24275482 John A. Jones, CISSP Americas Information Security Officer Jones Lang LaSalle, Inc. V: +1-630-455-2787 F: +1-312-601-1782 john.jones@xxxxxxxxxx -----Original Message----- From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Greg Wenzloff Sent: Friday, October 06, 2006 8:19 AM To: midrange-l@xxxxxxxxxxxx Subject: Why do computers still have disk drives? It's Friday -- often a quieter day in the office. I was wondering why don't new computers like the i5 just have solid state memory and forget about disk drives. Think about it. You can get a 2GB thumb drive for $75 or less. Why can't the manufacturers just load about 200 GB of this solid state memory into the machine? Think of the speed improvement. Or am I missing something? Maybe need more coffee. Just my thoughts, Greg -- This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list To post a message email: MIDRANGE-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/midrange-l or email: MIDRANGE-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/midrange-l. This email is for the use of the intended recipient(s) only. If you have received this email in error, please notify the sender immediately and then delete it. If you are not the intended recipient, you must not keep, use, disclose, copy or distribute this email without the author's prior permission. We have taken precautions to minimize the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses. The information contained in this communication may be confidential and may be subject to the attorney-client privilege. If you are the intended recipient and you do not wish to receive similar electronic messages from us in future then please respond to the sender to this effect.
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