I am looking for some 64Gbyte USB flash drives - preferably in slim
casing. This one looks ideal as a form factor:
But the Amazon reviews for that and similar products report that they -
or, at least, some of them - get very hot in use. Naturally, the heat
comes from consuming a lot of power, and that would not be good in a RPi
or anywhere else. (One use I have in mind is to put three of these in a
USB hub where the ports are close together and, of course, Pi USB ports
are _very_ close.) Apart from putting a load on a small PSU, running hot
could affect the working life of flash memory. Some Amazon reviews
report that hot USB flash drives fail after a few months. Bad news when
precious content is stored on them!
I see in a previous thread that Amazon reviews can be for related
products rather than the specific one a customer buys. So I wondered if
you guys had come across any particular flash drives that were slim
enough to fit in adjacent Pi ports but did not get uncomfortably hot
while in use.
Any make/model suggestions?
Use a powered USB hub.
Remove the case (unless it acts as a heatsink, as the metal ones may)
and attach a heatsink or place a small fan nearby, or stick a Peltier
device on it.
Just insert a new stick and restore from backup - you do have backup,
If content is that precious, then get a small SSD and a USB to SATA
adaptor. They are far more reliable, and don't get as hot.
If you do need the flash drives for some other reason, then the larger
the stick, the less hot they appear to be (although the chip itself is
probably at the same temperature, the bigger stick is better at
dissipating the heat), but then you aren't going to be able to put them
I normally use the Samsung bar USB sticks. It's metal cased so good for
dissipating the heat, and small enough to get them side by side in USB
ports. They don't stack as close vertically due to the hoop at the end.
This email has been checked for viruses by Avast antivirus software.
I have a ton of thumb drives, from 8 to 128GB and the 8's aren't long for this
world. Mostly I buy cheap based on the size I want, lately all 128's. Recently
I got a PNY 64GB USB 3.0 to put AVI movies onto and watch on my Kindle (I use
HandBrake and my own DVD's). It already has a, mostly full, 128 in the slot.
I've used it on a dual processor laptop and if I though it was hot I attributed
that to the fact the computer runs flat-out 100% CPU utilization 24X7. When
I've used it on the Kindle I haven't really noticed anything unusual about it,
heat/battery. Recently I had a couple of the same, physical dimensions wise,
plugged side by side into a Raspberry to play with, audio/video files, starting
to abhor Kodi and have decided that Audacious is my choice for audio. YMMV.
Backups of system drives are a pain. They are always missing the latest
info. You don't find out whether they are good or bad until you need
them. And they don't always work properly on a running system, needing a
shutdown to effect.
I want to go the other way - from a disk to solid state memory - for
I see that. It's a weird case. The Samsung duo looked better but then I
found that the USB connector was at the 'wrong' end!
That kind of CPU util can mean that something is looping unnecessarily -
at least on a dual-core laptop.
I've read about many USB flash devices that they can run /very/ hot.
Perhaps it's a feature of the technology and consumer devices are not
built with enough cooling to be read/written continuously.
What is it about Kodi that you don't like?
Metal cases don't appreciably differ from plastic cases in thermal
characteristics unless the chips have a thermal connection to the case.
The air inside is a very good thermal insulator. Likely the PCB
conducts more heat out from the chip than gets through the air and the
PCB is a good insulator.
I suppose the metal of the case helps to spread whatever heat does reach
it, but the thinness of the cases means neither the plastic or the metal
present much resistance to heat flow compared to the air and PCB getting
the heat from the chip to the case.
Is there any indication they use a thermal pad inside the case to
connect the chips to the case?
Use rsync as your backup tool. Been using it for years and had no
problems with backing up system disks on a running system.
Rsync is faster than tar, once its done the first backup, because it does
the minimum of work needed to make the backup identical with the disk its
backing up. Use a cycle of at least two backup disks/sticks/SD cards
and store them offline so a mains spike can't hurt them and preferably in
a firesafe or a different building.
martin@ | Martin Gregorie
gregorie. | Essex, UK
True. Sorry to druck for not reading his/her post properly. An SSD might
be an option for some applications. But I think I would rather have
multiple raid-1 USB sticks - if I can find some that don't compete with
Ah, but how many times have you restored a system disk? AIUI because the
system is running when the backup is taken - even with the brilliant
rsync - not all data will be stored on disk. It, therefore, won't all
get backed up.
I use rsync mirroring for system backup and I think I had to do a
restore once. It was much better than nothing but still left the system
needing a bit of fettling to get it working properly. Things like mysql
database tables were, presumably, cached in memory - leading to the
rsync'd database tables being broken and, even when fixed, inconsistent.
I do database backups into sequential files and they get rsynced but all
such backups are, of necessity, out of date. And unless the database is
stopped between such backups the tables could still be inconsistent with
AISI there are two types of backup:
1. those which let us go back to an earlier state (which you are talking
2. those which are used to prevent or allow recovery from disaster
Both are useful but unless an OS has effective inbuilt system-drive
backup I can't see how any file or drive backup tool can perform a real
snapshot. There could always be some data which are only half written to
disk when the disk copies are the bits which get backed up.
A true system backup would really need a system shutdown first.
As far as I am aware there are no true system backup options in a
running Raspbian or any other Linux OS.
As an aside, one of the few ways a true system backup can be performed
is in a VM. A host system can allow an entire guest OS image to be
snapshotted, and then later restored to that snapshot on demand. The
snapshot contains files and memory contents and running programs. The
restored snapshot therefore continues where it left off - even though it
may get a bit confused by a sudden change in the time of day.
Speaking of offsite backups, I have considered using rsync to back up
data disks across the internet. That could be a good way to go for
anyone who has, say, some cloud storage or, perhaps, comes to a
reciprocal agreement with a friend.
But to guard against hardware failure of system drives raid-1 seems
best. That would probably be one of the first things I would do with USB
BOINC, does the same thing with the quad AMD machine and I expect the same thing
when I get a quad INTEL machine later this week. I heat the house with natural
gas but the electrical energy supplements it. I live most of the year in cold
climates with the heat running.
Takes over everything, screws with my audio output device (although I remember
there being a configuration fix to bring it back to Analog on exit. Then again
I can see scenarios where I'd need to easily pick between Analog or HDMI or
BlueTooth.) Pretty much locks the machine when trying to exit (seen lots of
"fixes" for that also, I recall using something like a Ctrl-Alt-F1 with some
success), messes with my TV (CEC), another fix to configure, and the TV is both
a plain vanilla TV and a monitor for another computer. I'm not expecting Kodi
to be used that much, perhaps a few hours per week, and that could easily drop
to zero if I find an acceptable replacement. The pain/reward ratio doesn't seem
to be good. Mostly it's setting here running BOINC and Audacity 24X7 (for
audio, I listen to music starting about 9am until 10pm daily, I use XMPlay/VLC
on the Windows machine or VLC on the Kindle or DeaDBeeF/gPlayer/VLC on the linux
I move around a lot so the computing configuration changes frequently. I'd
really like to figure out fixes for these things so I don't have to haul around
pounds of equipment every time I move (I "live" in 3 different places and, as an
exception to normal, also spent about 2 months last year out of the country).
Again this all just my opinion and worth every .
Quite a lot, actually. I went through a phase when my system disks were
failing about every two years. Never found any lost data from any of thos
recoveries: SOP was to do a clean Linux install on the new disk and then
overwrite the /home partition from the backup.
Databases are different. I do two backups there:
- one is an incremental backup written as part of the system
maintaining the DB.
- the other is a whole DB dump using a standard utility which dumps
tables as CSV files interspersed with the SQL statements needed to
recreate and reload the tables.
My preference is to restore the database by using my incremental backup
files, which are designed for reasonably easy & fast replay through my
own batch loader. BTW, this is PostgreSQL, not MySQL, and I've had
problems with the Postgres backup in the past due to a broken CSV
implementation which couldn't handle fields containing the the character
used as quote marks.
If you're sensible you shut down anything that's likely to make changes
in response to external events while backing up. I stop mail clients and
web browser (mainly because I want to clear out history before taking the
backup) and I know that DB won't be updated (no clients running), buts
the regular offline stored weekly backup. rsync will tell you about any
files that change while you're backing up but I see that about once every
six months - and its almost always a system log.
I also have an automatic overnight backup to an always-online disk, so
its really only good for far-finger protection. That uses compressed tar
backups of the /home and /var partitions and also reports it when a file
changes during a backup. This is also a rare event, happening no more
than 2-3 times a year, and again its almost always a system log that gets
I think its good enough - see above, but you can always get a clean
backup from RAID 1: offline one of the mirrors, back it up and then put
it back online afterwards. Back in the days of 14" removable disks when
Stratus fault-tolerant systems ran RAID 1 using paired drives it was even
simpler - you knocked one of the plexes off line, and swapped its disk
pack for the one in the firesafe and fired the drive back up. The same
trick should work equally well with 2.5 or 3.5 disks in hot-swap disk
Yes, over a VPN to a friend's system sounds like a good plot. Dunno about
your cloud suggestion - some of them have been losing a bit of data
....with some caveats:
(1) you still need offline, and preferably offsite, backups
(2) make sure the mirrored drives are from different batches or
(3) Use hot-swap caddies or external USB or SATA drives.
martin@ | Martin Gregorie
gregorie. | Essex, UK
Did your system backups not include settings in /etc, installed apps,
email repositories, logs, etc?
You could run
The second mirroring rsync should run quickly and capture changes since
the first. Still no guarantee over logs, though.
That's a good idea. It still won't necessarily capture changes of open
files being written. But it sounds like it may be the best option
without OS support or a VM.
Have they? Very naughty!
I use a brilliant set of caddies for 5.25-inch drives - the Icybox
IB-168SK-B. They are good because drives can be simply swapped without
need of a screwdriver to attach tray or runners. (The enclosed versions
'169' with the 30mm are poor due to fan failure but the 168s are open
and use case airflow.)
The 168s are not perfect, though. Their LEDs require connection to a
driver port rather than snooping the SATA interface. Motherboards
usually only have one such driver header for every disk. And the 168s
don't allow you to see which disk is in which drive. I use post-it notes
which protrude past the drive door.
Depends. The weekly backup does, but the overnight run doesn't directly.
I have hacks:
1) /home contains a local and a java directory that are symlinked as /usr/
local and /usr/java, so backing up /home cpatures them too and all I need
to do after a clean install is to relink them. /usr/java doesn't exist in
a clean install and /usr/local does but its directory structure is empty.
2) and changes I make explicitly to files in /etc are copied to a
directory in my main login directory, so after a clean install, its
simple to copy them back to /etc and run systemctl to enable and start
the services they affect.
3) I also have a set of scripts to set up users and groups for my various
logins, relink /usr/local, and reinstall packages that aren't part of the
standard iso used or clean installs.
4) I put /home in a separate partition so that everything under /home
will be unaffected by a clean install when all the other partitions are
I don't care about the log files in those circumstances.
Long ago I configured Apache and Postgres so their data is part of /home.
This means that, with my recovery strategy after a disk failure, the only
real reason for backing up /var is to keep the mail spools.
There's nothing in /boot, /root and the rest of the root-level directory
structures apart from /home and /var that I care about and that isn't
automatically rebuilt by a clean Linux reinstall.
The problem is that people *assume* that the regional part of a cloud
they're using is automagically backed up and replicated to another cloud
region AND that if their region fails they'll be automatically linked to
the replicated copy. Then they find out the hard way that one or more of
those assumptions were false and realise they don't have local backups of
If you read The Register you'll see that cloud failures and resulting
lost data are no less frequent than similar webhost and mailhost failures.
The Amazon and Azure clouds seem to be better than the rest in this area,
but even they have regional failures from time to time.
martin@ | Martin Gregorie
gregorie. | Essex, UK
If it was kept still, yes. However convection makes it a very good
conductor. Never heard of wind chill? How do you thijnk a heatsink with
fins works if not by transferring heat to the air, which then takes it away?
Likely the PCB
All the heat reaches it eventually.
With electronics, what really counts is not having a sealed case.
A few CC of air every minute will carry away a lot more heat than a few
sq cm of case, metal or plastic. Althoiugh metal is a lot better.
"In our post-modern world, climate science is not powerful because it is
true: it is true because it is powerful."