James, Would it help to mark the content partition(s) as read only? Sameer On Aug 16, 2015 5:13 PM, "James Cameron" <qu...@laptop.org> wrote:
> Thanks, interesting questions. > > No, ext4 is not a slow journaled filesystem, and no, there are no > obvious problems on SD when using ext4 given your use case. But it > isn't operating system portable, and as your content is static no need > for a journal. Other features of ext4 make mounting or filesystem > check faster. > > Yes, wear-leveling is taken care of by the firmware in the card, put > there by the manufacturers. Wear-levelling also critical during > reading, since a flash page can't be read repeatedly without > disturbance eventually requiring it to be written to a freshly erased > page. This is all handled by the firmware. Happens way more > frequently than it does on a hard drive. > > Duplication time of SD cards won't be affected by your filesystem or > partition decision. > > One partition is sufficient. MBR partition type best, for > compatibility across the operating systems. > > For filesystem, use FAT32, mounted read-only. FAT32 works across most > Windows and Mac computers, at media sizes up to 2 TB, for file sizes > up to 4 GB. > > Where content cannot live on FAT32 due to file name character set or > metadata, it can be placed in disk image bundles of ISO-9660, > squashfs, or ext4 and loop mounted. The content curation process for > the end user might be easier if bundles can be added and removed as > needed. > > What you might be overlooking; I/O bandwidth of the connection to the > media, endurance impact of reading data from the card slowing > performance one year on, backups, content bundle tamper checks, risk > of filesystem format incompatibilities introduced by new versions of > operating systems after your product is in the field, risk of cross > system malware infections, electrostatic discharge damage to the card, > and how modern cards can change performance behaviour as a result of a > production state awareness flag stored by card firmware. > > On the other hand the alternatives have their own problems. > > -- > James Cameron > http://quozl.linux.org.au/ > _______________________________________________ > Server-devel mailing list > server-de...@lists.laptop.org > http://lists.laptop.org/listinfo/server-devel >
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