I am looking for some 64Gbyte USB flash drives - preferably in slim casing. This one looks ideal as a form factor:
formatting link
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.
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, don't you?
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 close together.
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.
---druck
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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.
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.
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.
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martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
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 the stove.
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 each other.
AISI there are two types of backup:
those which let us go back to an earlier state (which you are talking about)
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 flash.
Nevertheless, if one of three raid-1 memory sticks failed it could be hot-replaced and the array would continue uninterrupted. (Two would be enough but three would be safer.)
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 machines, depending).
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).
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 hit.
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 caddies.
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 recently.
....with some caveats: (1) you still need offline, and preferably offsite, backups (2) make sure the mirrored drives are from different batches or different manufacturers (3) Use hot-swap caddies or external USB or SATA drives.
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martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
Did your system backups not include settings in /etc, installed apps, email repositories, logs, etc?
You could run
rsync sync rsync
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!
Good suggestions.
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 reformatted.
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 anything.
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.
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martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
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
More blatherskite.
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.
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