OEM emonSD Industrial 32GB card Formatted Size?

emonSD
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I bought a couple of spare OEM Industrial emonSD 32GB cards at the end of September 2022. I recently put one in my emonPi as a replacement for an old card. All is up and running ok. I had a look at Admin/System Information and found the following in the Disk section -

/                              4.07GB
/var/opt/emoncms               9.84GB
/boot                            252.05MB
/var/log                          50MB

which looks like about half the formatted card. I had a look at the unused second card in KDE Partition Manager, and it had an unallocated section of 15.3GiB.
Is there any reason for only using half the card?
I don’t know much about wear levelling, but I would guess that spreading the writes across double the storage space would result in less wear per block?

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If the flash media you’re using incorporates wear leveling (not all of them do)
wear leveling will spread the writes to any available block. The WL algorithm doesn’t know
(or care) about partitions, File Allocation or Inode tables, etc.
Those are handled by the Operating System.

By not allocating the entire drive, you’re losing out on capacity but little else.

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@Bill.Thomson Thanks very much for the reply and the explanation. I’ll have to read up on wear levelling!

1 Like
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The image used is this size and the partitions are not extended by the shop.

Don’t worry, it will take a good few years to fill it up (although OS updates will fill the root partition).

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@borpin Thanks for the information. Would it break anything if I used a Linux partition manager to expand the / , /var/opt/emoncms and perhaps /var/log partitions while the card is still relatively empty?

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I think the rootfs partition is a bit marginal. I think Trystan has now expanded it.

TBH I’d leave it unless you want to do something specific. The card will wear out before you run out of space!

7

@borpin ok, thanks for the update.