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On 26 Sep 2008, at 19:21, James wrote: |
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> Neil Bothwick <neil <at> digimed.co.uk> writes: |
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> |
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> |
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>> Bear in mind the limited write lifetime of flash memory. Don't put / |
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>> var |
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>> or /tmp on such a card if you can avoid it. |
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> |
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> Well, I'm not sure any other alternatives are attractive? Unless |
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> I find a way to mount those partitions off of a usb stick, or |
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> some other idea? |
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> |
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> Since they are not frequently updated and have minimal installed |
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> software |
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> (iptables on firewalls and DNS on DNS servers) accompanied by the |
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> fact that most devices have internal wear leveling; it should take |
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> many years to reach the write cycle limits? |
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I've read a fair little bit about this subject and never gotten a |
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definitive answer on what is "safe", but AIUI the wear-levelling on |
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flash memory is filesystem-dependent. Thus it may work fabulously well |
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for FAT filesystems, and not at all for EXT. |
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Having said that, from my experience most of the nay-sayers telling |
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you not to put stuff on a CFcard for this reason are talking |
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speculatively - I have encountered one or two people who have used |
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CFcards very happily for years. It does seem sensible to store logs, |
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tmp & Portage directories on a RAM disk or hard-drive, NFS mounted if |
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necessary, but generally I would say just get on & try it. 4gig |
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CFcards are, after all, cheap as chips these days. Oh! It may be |
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possible to reduce the number of writes to the card by changing mount |
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options in /etc/fstab and have writes flushed less frequently. |
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You might consider posting about this - or merely searching the |
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archives - on the MythTV users list, as the subject does come up |
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periodically and there are a number of people using CF cards in this |
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way to reduce noise in the TV room. |
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>> You could dd the card to a file and use the same file every time |
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>> you need |
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>> a new card. |
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> |
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> Um I do not mean to be a pain, but could you provide a little bit |
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> of pseudo-syntax? Assume I have shutdown a 4 GB CF firewall card |
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> and moved it to a reader/writer on another machine. First I need |
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> to format the raw (new) 4GB CF card from a reader. |
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Put CFcard with existing filesystem in card-reader: |
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dd if=/dev/sdX of=~/diskimage.img |
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Swap cards in reader, writing to blank now: |
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dd if=~/diskimage.img of=/dev/sdX |
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You need to ensure that neither card is mounted when following this |
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procedure - booting from a LiveCD or 3rd filesystem. |
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Stroller. |
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