I would say since those thumbdrives are solid state, theoretically they should last forever, barring fire, flood, act of God, or static discharge . .
I'd like to do that myself, get an 8 GB thumb and install SuSE on it and run it on the St. Joe library machines, completely bypassing their native o/s. I don't think they'd like it unless I could prove to them it wouldn't muck up something in Windoze (version of the week).
Gary Hildebrand St. Joe, MO
From: "Brian Kelsay" ripcrd@gmail.com Subject: Re: Installing Linux to a 4gb usb microdrive
There's info out there on how to prevent excessive writes. Google for Linux on a CF.
http://pendrivelinux.com/ In Linux disable the swap and use the no atime option in your fstab. Turn off logging or log to a remote server. Brian
I was thinking more of speed. They've got to be faster than a hard drive. I've got this cute little adaptor that takes one of the SD cards and converts it into and IDE connection. But the flash memory has a limit on how many times it can be erased before they are damaged. It's quite high but I can see /tmp or /var hitting that limit. I was thinking of putting those partitions on an actual hard drive. The little card can be "locked" so no information can be written (it's a jumper). So once you install Linux it would 1) boot quickly and 2) couldn't be changed unless you had physical access to the box.
gary hildebrand wa7kkp@gmail.com wrote: I would say since those thumbdrives are solid state, theoretically they should last forever, barring fire, flood, act of God, or static discharge . .
I'd like to do that myself, get an 8 GB thumb and install SuSE on it and run it on the St. Joe library machines, completely bypassing their native o/s. I don't think they'd like it unless I could prove to them it wouldn't muck up something in Windoze (version of the week).
Gary Hildebrand St. Joe, MO
From: "Brian Kelsay" ripcrd@gmail.com Subject: Re: Installing Linux to a 4gb usb microdrive
There's info out there on how to prevent excessive writes. Google for Linux on a CF.
On Jan 11, 2008 12:17 PM, James Sissel jimsissel@yahoo.com wrote:
I was thinking more of speed. They've got to be faster than a hard drive.
I was going down that road once myself, then I started checking the transfer rates between IDE/SATA magnetic drives and Flash cards via IDE/SATA -- the harddrives seem all around faster.
On Jan 11, 2008 12:17 PM, James Sissel jimsissel@yahoo.com wrote:
I was thinking more of speed. They've got to be faster than a hard drive. I've got this cute little adaptor that takes one of the SD cards and converts it into and IDE connection. But the flash memory has a limit on how many times it can be erased before they are damaged. It's quite high but I can see /tmp or /var hitting that limit. I was thinking of putting those partitions on an actual hard drive. The little card can be "locked" so no information can be written (it's a jumper). So once you install Linux it would 1) boot quickly and 2) couldn't be changed unless you had physical access to the box.
You can use tmpfs for /tmp, and I suppose /var if you don't care about saving logs from one boot to the next. You could probably even use tmpfs and then save any files to some other location at shutdown and read them in at boot. You'd need plenty of RAM, of course.
Make sure you use a good quality CF, too. In our experience at work, SanDisk is good but Kingston drives will fail unless you leave around 10% of it unformatted.
I'd mount your root partition read-only if at all possible. Definitely use noatime, too.
On Friday 11 January 2008, gary hildebrand wrote:
I would say since those thumbdrives are solid state, theoretically they should last forever, barring fire, flood, act of God, or static discharge .
Uh, no. Flash drives are known to have a limited number of writes after which they get stuck. That's why you never put swap on a Flash drive.
On Jan 11, 2008 3:18 PM, Luke -Jr luke@dashjr.org wrote:
On Friday 11 January 2008, gary hildebrand wrote:
I would say since those thumbdrives are solid state, theoretically they should last forever, barring fire, flood, act of God, or static discharge .
Uh, no. Flash drives are known to have a limited number of writes after which they get stuck. That's why you never put swap on a Flash drive.
Agreed. Run without swap if you are running off of flash, unless you like making trips to MicroCenter.
There is a significant lifetime difference between low and high density flash. (I forget the actual technical names.) The low density lasts longer and it is also faster. Technically, this is because each memory location in the low density holds one bit (and is read simply high or low) while the high density holds 2 bits per location (which requires more precise reading of intermediate steps).
The difference in lifetime is roughly "It will last a year" versus "It will last until I die". The difference in cost is pretty significant, also. The good ones are the high-end, high-speed ones sold mainly for photography purposes.
---
I just looked it up - it's SLC vs MLC. http://www.edn.com/index.asp?layout=partnerContentDetail&articleid=CA631...
On Jan 11, 2008 3:38 PM, Eric Johnson ericlj63@gmail.com wrote:
On Jan 11, 2008 3:18 PM, Luke -Jr luke@dashjr.org wrote:
On Friday 11 January 2008, gary hildebrand wrote:
I would say since those thumbdrives are solid state, theoretically
they
should last forever, barring fire, flood, act of God, or static
discharge .
Uh, no. Flash drives are known to have a limited number of writes after
which
they get stuck. That's why you never put swap on a Flash drive.
Agreed. Run without swap if you are running off of flash, unless you like making trips to MicroCenter.
There is a significant lifetime difference between low and high density flash. (I forget the actual technical names.) The low density lasts longer and it is also faster. Technically, this is because each memory location in the low density holds one bit (and is read simply high or low) while the high density holds 2 bits per location (which requires more precise reading of intermediate steps).
The difference in lifetime is roughly "It will last a year" versus "It will last until I die". The difference in cost is pretty significant, also. The good ones are the high-end, high-speed ones sold mainly for photography purposes.
I just looked it up - it's SLC vs MLC.
http://www.edn.com/index.asp?layout=partnerContentDetail&articleid=CA631...
--
Eric Johnson
"Where your pleasure is, there is your treasure: where your treasure, there your heart; where your heart, there your happiness." Saint Augustine _______________________________________________
Ok -a stated i another thread- The device I a trying to use is an actual hard drive just a very small one. it's called a Microdrive and they are the heart of smal hs based music players. There was a time when certain players had a street price of 1/3 the cost for that size microdrive itself! Which caused some OEM embedded drives to be BROKEN BY DESIGN from having such "Drive Harvesting" possible. The sordid details might take some Google Fu but it's documented. Perhaps a new thread on Linux rescuing such borked in firmware itemes is in order?
Well- the device I am using seems made for projects like mine. There are IDE to CF converting units that a CF microdrive can run from, but the Zen of a detachable USB device as a microcosm is more elegant. Here's the pitch on Gary's idea.We use one FAST expensive drive as Write once read many,. and CHEAP disposable drives as flash drive. Being serious- how much use will it thke to kill even a swap device? Then we look at a 1gb device being Eight bucks- ok we round it up to ten to cover travel and taxes etc.Ten bucks a GB for "Sacrificial Flash" may be an experiment worth kicking around? And I have a WtF inducing concept beginning a new thread. HINT: How many USB drives can Linux support at once?
Oren Beck wrote:
Write once read many,. and CHEAP disposable drives as flash drive. Being serious- how much use will it thke to kill even a swap device? Then we look at a 1gb device being Eight bucks- ok we round it up to ten to cover travel and taxes etc.Ten bucks a GB for "Sacrificial Flash" may be an experiment worth kicking around?
Supposedly cheaper flash units can sustain fewer than 100,000 writes, but better ones can handle upwards of 500,000. Now, I've also read that a lot of systems attempt to spread the writes over the media rather than repeatedly writing to the same location. I assume that such a feature would be in the fs software, rather than in the flash hardware itself, so fs choice is also something you will want to strongly consider for your experiment.
So, with a 1GB flash @ 30MB/s write speed (mine can only do about 9MB/s), with a fs that attempts to distribute writes over different sectors, constantly writing, you would have hit the rated max writes of 500,000 writes per sector at about 6-7 months (I think).
However, most people use FAT32 (for compatibility), and continually write over the same sectors, in which case you could feasibly kill sectors of the same type of drive in only minutes (if you were trying).
All of this is based on maximum write speed being maintained for the entire time... not going to happen.
Of course, I could be completely wrong :)
~Bradley
On Jan 11, 2008 6:40 PM, Bradley Hook bhook@kssb.net wrote:
Supposedly cheaper flash units can sustain fewer than 100,000 writes, but better ones can handle upwards of 500,000. Now, I've also read that a lot of systems attempt to spread the writes over the media rather than repeatedly writing to the same location. I assume that such a feature would be in the fs software, rather than in the flash hardware itself, so fs choice is also something you will want to strongly consider for your experiment.
A lot of this has been kicked around about the Eee PC and it's solid state storage. Better quality devices have wear leveling built-in to the flash controller as these aren't just raw flash chips stuck on the USB/ATA bus. A wear leveling FS can interfere with a controller that auto levels because it's trying to "second guess" how things are to be written. In general most controllers leave a certain percentage of the flash reserved for bad block management, just like a spinning HDD does. Also, many controllers use free space to level in by successively writing to empty blocks instead over writing the same block over and over. It's been postulated that it's better to leave empty space on the flash to give the controller more space to do the leveling in.
So, with a 1GB flash @ 30MB/s write speed (mine can only do about 9MB/s), with a fs that attempts to distribute writes over different sectors, constantly writing, you would have hit the rated max writes of 500,000 writes per sector at about 6-7 months (I think).
There's articles about hitting a flash drive at max speed constantly and it seems to be a function of available blocks to write to, as I wrote above. If you have 4GB of free space to level over you are going to have a lot more wear leveling being spread out and thus higher lifetime vs having 20MB free plus the bad block reserves to catch errors as they crop up and shortening life.
However, most people use FAT32 (for compatibility), and continually write over the same sectors, in which case you could feasibly kill sectors of the same type of drive in only minutes (if you were trying).
This is most likely linked to older controllers that don't do automatic wear leveling.
Jon.
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Arthur Pemberton -
Bradley Hook -
Eric Johnson -
gary hildebrand -
James Sissel -
Jon Pruente -
Luke -Jr -
Oren Beck