Bootable Linux USB stick: Difference between revisions

Bootable Linux USB stick (edit)

Revision as of 21:45, 20 January 2018

760 bytes added , 20 January 2018

→‎types of USB media

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 === types of USB media ===
-# very good: USB sticks that support TRIM. The ones known to us are: Sandisk Extreme USB sticks bought before 2017 (e.g. the 32GB model for ~22€ or 64GB for ~40€; unfortunately, these are no longer available), and some high-quality Mushkin models. These sticks are very fast (CrystalDiskMark scores >10MB/s for random 4K writes). Same holds for current (2018) Sandisk Extreme Pro USB sticks (only 128 and 256 GB models exist).
+The suitability of the media makes a notable difference, in particular when the operating system is upgraded, or CCP4 is upgraded, or when e.g. a new Phenix version is installed.
-# good: USB3 adapter with (micro)SD card (separate items). USB3 adapters are cheap (around 5€ at Amazon, like https://www.amazon.de/EX1-Kartenleser-Micro-Karte-Adapter/dp/B06XX3T219; cheaper at Ebay). microSD cards usually come with a SD adapter, and can be TRIMmed in SD slots from time to time. microSD cards ideally should be in the [https://en.wikipedia.org/wiki/Secure_Digital#Speed_class_rating Class 1 (A1) application performance class] since this is what is defined as requirement for use as extended operating system disk in Android smartphones. In practice, non-A1 microSD cards also seem to work well, but may require more often TRIMming.
-# acceptable: USB sticks that do not support TRIM but are fast and high quality, e.g. Sandisk Extreme Go or Sandisk Ultra bought 2017 and later. However, these may degrade with time.
+* very good: USB sticks that support TRIM. The ones known to us are the Sandisk Extreme USB sticks bought before 2017 (e.g. the 32GB model for ~22€ or 64GB for ~40€; unfortunately, these are no longer available). These sticks are very fast (CrystalDiskMark scores >10MB/s for random 4K writes). The successor are the differently-named current (2018) Sandisk Extreme Pro USB sticks, but only 128 and 256 GB models exist, and they are expensive.
-# inacceptable: e.g. Sandisk Ultra Fit become hot, degrade fast and are unreliable. For cheap sticks to be useful, one must be lucky.
+* good: we have verified that a USB3 adapter with (micro)SD card (separate items) is suitable. USB3 adapters are cheap (around 5€ at Amazon, like https://www.amazon.de/EX1-Kartenleser-Micro-Karte-Adapter/dp/B06XX3T219; cheaper at Ebay). microSD cards usually come with a SD adapter, and can be TRIMmed (but only in a SD slot; see below!). microSD cards ideally should be in the [https://en.wikipedia.org/wiki/Secure_Digital#Speed_class_rating Class 1 (A1) application performance class] since this is what is defined as requirement for use as extended operating system disk in Android smartphones. In practice, cheaper non-A1 microSD cards also seem to work well, but may be slower and may require more often TRIMming. The price/performance ratio of the microSD/USB3 combination is very good.
+* acceptable: USB sticks that do not support TRIM but are fast and high quality, e.g. Sandisk Extreme Go or Sandisk Ultra bought 2017 and later. However, their write performance may degrade with time (or rather, with the number of writes to a partition), and not much can be done about that.
+* inacceptable: e.g. Sandisk Ultra Fit become hot, degrade fast and are unreliable. For cheap sticks to be useful, one must be lucky.
+The drawback of the "good" solution above is: from time to time (e.g. once every week), a knowledgeable person must
+# remove the microSD card from the USB3 adapter
+# insert it into the SD adapter, and that into a SD slot
+# run the <code>fstrim</code> command (this takes a few seconds)
+# revert steps 2. and 1.
 === fill empty space of a partition with “zeroes” ===