> > I have read that SSDs have a much longer lifespan, and are a lot faster to > boot (pun attempt).
Completely false on both counts, depending on circumstances and subtracting the pun. SSD's are _usually_ faster, and don't have mechanical wear mechanisms. But there are also two basic facts of physics working against you: 1) The fundamental electron tunneling mechanisms used have a wear-equivalent behavior, and they literally slow down with every erasure. Depending on the technology, at a 10:1 ratio or worse. When near EOL, some devices can take 1/2 second or more PER ERASURE to finish. 2) Some flash technologies have a wear-out threshold in the hundreds (10^2!) of cycles. The best ones are only millions (10^6). 10^4-10^5 are the middle of the road. Most flash vendors don't want to tell you the raw numbers. The newest high-density MLC/TLC flashes are the worst. Plus, there are more factors: 3) Wear-leveling mechanisms, required in order to compensate for the above two conditions, are often not matched to the filesystem. This can result in highly-unoptimal use behavior of the raw flash device, causing accelerated wear on the flash. Yes, making things worse instead of better. Current trends are to integrate this necessary mechanism into the device, where it is opaque, unspecified, and unadvertised. By the time you find out it's actually shit, it's too late. Low-cost commodity devices are usually the worst. 4) The more full the SSD is, the less free space there is to push around for wear leveling purposes. A nearly full device will wear out much faster than a nearly empty one. 5) Retention is usually unspecified, but can be measured in months on the worst devices. Higher temperatures exacerbate the problem. For some heavy write-oriented applications, a traditional rotating disk will actually work better and last longer! A company I once worked for changed production from rotating to SSD, "to enhance reliability." Failure rates in the field went _up_! They did not switch to a flash-friendly filesystem format, and the traditional fs just wore the flash out in short order. The 'improvement' was made by the purchasing/marketing department, and engineering was neither involved nor consulted. Oops. OTOH, a truly optimal implementation, largely read-only and well-matched to the application, will really fly, last a long time, and will be immune to physical abuse. Our big Macs here at home use SSD for the boot/application disk, and rotating media for all the user files. They're blazingly fast in general operation, but a catastrophic SSD failure will not result in the loss of critical data. These machines all use Time Machine to back up to a server, which uses 2TB RAID HD's to catch. One of these raw HD's is rotated out to off-site storage quarterly, and the RAID is rebuilt with the oldest offline device. (4 2T mechanical hard drives in rotation, 2 serving 'live' at a time, 2 in separate off-line off-site locations.) Fast, and safe. -- Jim _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com