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manual: Document storage/capacity limits and "SSD Mods"

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Solomon Peachy 2024-09-21 11:00:53 -04:00
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manual/getting_started/installation.tex
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@ -268,6 +268,63 @@ of before installing.
\end{description}
}
\subsection{Storage/Capacity Limits}
\note{As of this writing, no Rockbox-capable device can handle
total drive capacities exceeding than 2TiB.}
\opt{disk_storage}{
Rockbox supports larger drive capacities when used on devices
that use ATA storage and GPT partitioning, but due to the limitations
of the FAT32 filesystem, individual paritions cannot exceed 2TiB. Additionally,
there are typically underlying platform limitations that
make it difficult, if not impossible, to boot from a GPT-partitioned
drive.
}
\opt{sd_storage}{
\note{SD cards exceeding 32GiB are pre-formated using the exFAT filesystem with GPT paritioning.
Before they can be used with Rockbox, they must be reformatted with FAT32.}
Rockbox does not currently support SDUC cards with capacities exceeding 2TiB. However, this is purely
a software limitation with Rockbox's SD card drivers, and will be addressed in a future release.
}
\opt{disk_storage}{
\subsection{Flash/SSD mods}
It is common to replace the device's original mechanical hard drive with
some sort of solid-state storage. Older versions of Rockbox (3.15 or prior) do not work properly with many
of these so-called ``flash mods'', the most common symptom being data corruption on write operations. All
known data integrity issues have been resolved, but each type of adapter has its own quirks:
\begin{description}
\item[Compact Flash.] True Compact Flash cards \emph{natively} implement the ATA command set, including
advanced power management and the \emph{removeable} attribute. They are performant, reliable, and physically
robust, but tend to be expensive and not available in larger sizes.
\item[SATA.] These are fast, reliable, and available in high capacities, but are typically optimized for high performance
at the expense of power consumption.. However, as they implement the full ATA command set, we are able
to aggressively power them down when not being actively used.
\item[Single Secure Digital (SD).] While these adapters come in different form factors from multiple vendors,
they are all based on the same basic design. The ATA command set is \emph{incompletely emulated}, notably lacking
support for the \emph{mandatory} ATA power management commands that Rockbox uses to flush caches and safely
transition the device in and out of low power states. Additionally, SD cards themselves vary widely in quality
and power consumption, leading to widely varying battery life. Finally, they do not support SDUC cards at all so are
limited to individual cards of 2TiB or less.
\item[Dual/Quad SD.] These are similar to the above, only allowing use of mulitiple SD cards to
increase the overall storage capacity. While typically described as JBOD\footnote{Just a Bunch Of Disks}, this is not accurate as each
card is not individually accessable. Instead, the adapter claims to be to be a single logical drive
that is the combined capacity of the individual cards in a RAID0-like manner. This also means that if any
one card fails, you lose everything. Combined with the poor quality of most SD cards and the lack of support
for proper power management, this means use of multiple SD cards in one of these adapters is the reliable and most
power hungry solution of all. Finally, in another violation of the ATA specification, these ATA<->SD adapters fail
to support addresses exceeding 32 bits, meaning that no matter which combination of cards is used, they simply will
not work if their combined capacity exceeds 2TiB.
\item
All of these flash/SSD mods take up less physical space in the device enclosure than the original hard drive, so care
must be taken to ensure they are securely mounted and resistant to the vibration and impacts that typically occur
in portable devices. Ribbon cables are particularly vulnerable.
\end{description}
}
\section{Installing Rockbox}\label{sec:installing_rockbox}\index{Installation}
There are two ways to install Rockbox: automated and manual. The automated
way is the preferred method of installing Rockbox for the majority of