On Sun, 15 May 2011, walter marvin wrote:
> It the writes per cell that is the limit not total writes journaling will
> repair a cell that has had too many writes
Yes but misleading. All flash based devices like USB sticks and SD cards,
CFdisks etc contain wear levelling. Where the journal is stored will move
about the flash blocks to spread the wear out.
I repeat, increasing the total number of writes to the flash devices
increases the wear on the flash memory. Whether this is important in one's
application is upto the engineer to determine. Just ignoring it with bland
platitudes is not sensible engineering.
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> --- On Sun, 5/15/11, Jim Jackson <> wrote:
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> From: Jim Jackson <>
> Subject: Re: [ts-7000] TS-7553 MicroSD longevity
> To:
> Date: Sunday, May 15, 2011, 5:27 PM
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> On Sun, 15 May 2011, walter marvin wrote:
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> > My info is infinite reads but limited writes this means that you must use
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> > a journaling file system or build in track remapping
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> Not sure that makes sense. In fact a journalling file system INCREASES
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> writes - first to write the update details to the journal, then to
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> do the updates, then the make the update done in the journal.
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> The use of a journalling file system helps if the system is likely
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> to suffer unexpected power loss etc. When it comes back up, any uncompleted
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> transactions can be verified and completed, and there is usually no need
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> for a very lengthy file system integrety check.
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> As an engineer it's up to you decide the trade offs and decide which is
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> more important. My own systems have battery backup, allowing graceful
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> shutdown, so I use ext2 (mounted with "noatime") to reduce writes. If I
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> didn't use battery backup, I'd use ext3, and stand the write hit to give me
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> better file system integrety.
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> > --- On Sun, 5/15/11, parkranger_dan <> wrote:
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> > From: parkranger_dan <>
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> > Subject: [ts-7000] TS-7553 MicroSD longevity
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> > Date: Sunday, May 15, 2011, 1:37 PM
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> > Hey guys. I posted awhile back when having some functionality issues with a TS-7200 and realized the 7553 was really the platform I should have been working with from the get-go.
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> > Sweet little box this 7553. I've gotten all my software ported over and it's working perfect. After only a couple weeks with it, I think I'm ready for deployment.
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> > We'll be preparing quite a few of these little guys. Having the ability to insert a pre-imaged MicroSD, set one jumper, and run one command (rm linuxrc; ln -sf /linuxrc-sdroot /linuxrc; save) to change the boot is very attractive in terms of quick deployment, and easy field upgrade (send customer a new MicroSD card, done!).
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> > One question I had was in regard to the longevity of these little MicroSD cards, and their resilience to repeated power loss.
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> > Customers will not have the ability to shutdown nicely, power will always be removed to turn off. I based my image from the latest.dd image available from the Technologic website, which if I remember correctly is formatted ext3.
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> > Has anyone had any experience with a similar setup? How are the boxes holding up, and have the MicroSD cards been lasting?
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> > I've been also pondering making use of the xnand drive with a custom busybox that includes the compiled apps i need and just script the flashing process to ease prep/deployment. I know bootup time would be significantly better than my current 1 minute timeframe, and resilience would be better. Downside would be that I lose the ability to do remote software updates. Anyway, I have yet to break ground on that idea, or even wrap my brain around how that's done.
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> > Thanks!
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> > Dan
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