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VinzC
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 Posted: Tue Aug 05, 2008 9:54 pm Post subject: Does it make sense to format USB sticks with JFFS2? |
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... as JFFS2 is there only to put a filesystem directly on a flash card. USB sticks do have their own intermediate layer, am I right? So is it advisable to format just about any USB memory stick?
Thanks in advance.
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jstead1
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| Posted: Wed Aug 06, 2008 3:23 am Post subject: |
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I am not familiar with JFFS2, but you should be able to format a USB drive with pretty much any file system. One thing that will help prolong the life of the USB drive is to disable access times (atimes). Otherwise, every time a file is accessed, the drive is updated with the latest access time, causing more writes on the drive. Unless knowing access times is important, it would be best to use a file system where access times are not used, or can be disabled.
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VinzC
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| Posted: Wed Aug 06, 2008 8:06 am Post subject: |
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| jstead1 wrote: | | I am not familiar with JFFS2, but you should be able to format a USB drive with pretty much any file system. One thing that will help prolong the life of the USB drive is to disable access times (atimes). Otherwise, every time a file is accessed, the drive is updated with the latest access time, causing more writes on the drive. Unless knowing access times is important, it would be best to use a file system where access times are not used, or can be disabled. |
Thanks for the info. In fact I knew that access times were as lethal as you described. I asked the question because I read someone asking almost the same question and the reply was there is no need to use JFFS2 on USB pen drives. (Probably because there was already a certain level of abstraction inbetween; at least this is how I understood the answer.)
The purpose of JFFS2 is to spread block writes across all the available blocks to prevent writing to the same ones all over again.
An interresting question is about atimes: when I mount a device and I'm using XFCE4 the filesystems are mounted automatically. I have no fstab entry for these. So am I supposed to write UDEV rules to add the "don't use atimes" mount option or should every Desktop Manager be able to handle that? (I would be glad to see Desktop Manager handle that for me or at least provide options to disable access times. Putting an entry in fstab would kind of decrease flexibility to me...)
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drescherjm
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| Posted: Wed Aug 06, 2008 2:40 pm Post subject: |
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| Quote: | | The purpose of JFFS2 is to spread block writes across all the available blocks to prevent writing to the same ones all over again. |
In most cases this is already done by the USB stick (should be called wear leveling) so doing it a second time is probably counter productive.
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VinzC
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| Posted: Fri Aug 08, 2008 11:10 pm Post subject: |
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| drescherjm wrote: | | Quote: | | The purpose of JFFS2 is to spread block writes across all the available blocks to prevent writing to the same ones all over again. |
In most cases this is already done by the USB stick (should be called wear leveling) so doing it a second time is probably counter productive. |
Thanks, this is also what I understood after reading the post I talked about. If I've understood JFFS2 is usefull only when directly accessing the Flash memory hardware, i.e. without intermediate layers like the ones we have with USB flash memories.
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