I am considering including duplicating to bluray once or twice a year into my backup strategy and would appreciate input on pros and cons.  Advantages I assume:   immune to EMP/electric surge   Disadvantages I assume:   slow limited space only write once   Am I correct in my assumptions? What other advantages and disadvantages do this medium have? What is the life expectancy of an optical disc? How far from an atomic blast will they survive?  Edit: I do not feel that my question is a duplicate of the suggested questions. Their answers do contain relevant information but the questions themselves have a different primary focus.
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This question was inspired by . There have been other similar questions, but none with the same criteria.  This is two questions in one.   How do you store financial/critical records that should survive anything but a fire and should be available for decades? Lets say I want to store family photos/videos and want people do be able to find them in storage 100 years from now and still be able to use them. How would this be done?   Criteria   Long term means 30+ years guaranteed. 100+ years average. [If this is not practical, use the closest solution] High volume means a couple terabytes. Answers can be 'no-compromise/industrial' solutions or practical solutions for the home office/small business user. Media will not be active during the timespan. (i.e., if you suggest hard drives, they will not be spinning).  Further, there is no expectation of needing to read these archives. They are there for emergency or "for future generations" purposes. Should not require maintenance (if at all possible).    My thoughts:   CD-R/DVD-Rs have proven to me, even in the short term, to be a terrible medium for backups. They seem to be very fragile and seem to lose their data a very short time even when in pristine condition. I can't help but think that storing data on a couple of 1TB hdd's and then expecting them to spin up correctly a decade or two later to be a terrible idea. Am I wrong? Industrial tape drives seem like a viable option?
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This question seems similar to , but my needs are different :   I shoot in RAW exclusively I'm looking for a 100% offline solution: while traveling, Internet won't be accessible the "laptop" solution is too heavy for me: I'm looking for a lightweight solution the simplest, the better: one device to rule them all   EDIT:  I'm using good old Compact Flash cards (yes, the bigger ones), so I need a device that can read it. If it can read from other cards, this question might be interesting for more people than myself  - that's the whole purpose of the website.    Also asked by :  Portable Storage Device while traveling  I need storage device which is able to read CF cards and make a backup of my photos while traveling. I do not want to carry laptop (it's bulky) and tablet (too little storage) but looking into some other solutions.   So far I found:   Epson PXXXX - price is blocker for me Jobo Giga Vu - same as above Nexto DI - bit better, but still a lot Hyperdrive Colorspace UDMA - this looks the best for price/options Wolwerine PicPac - cheap, bad opinions DigitalFoci PhotoSafe - same as above Ex-Pro® Picture 2 Drive - didn't find much about it   So ladys &amp; gents what do you use?
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(This was originally asked on SuperUser --- they pointed me here as being more appropriate.)  I have a shiny new Debian server running in an Amazon EC2 instance. I've spent a while setting it up and it now works nicely. However, because it's a cloud server, if I (or someone else) presses the wrong button then its virtual hard disk will go pop and I have to do it all over again. So, I want to make backups.  But I'm paying by the byte for storage, so I want to make a small backup.  It should be possible to backup a complete Debian server by recording the set of currently installed packages (which I can do via dpkg --get-selections), the state of the debconf database (which I can do via debconf-get-selections), and then only backing up files that cannot be trivially replaced from the packages --- i.e., everything else. Then restoring the backup should be a matter of reinstalling the packages and dropping the files on top.  The tricky part is determining which files belong to a package and which files don't. Having a static list of subdirectories to backup isn't really good enough due to cruft creep. I need a way to automatically determine whether a particular file needs backing up or not.  This is precisely the sort of thing I don't want to do myself because I'll get it wrong. Are there any tools to allow me to do this?  (Note: I'm not looking for an incremental backup solution. I want to take a complete snapshot.)
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I have been struggling with .mp4's for about 2 days now, trying to concatenate a series of about 20 into 1 single file. Any differences between the files and it is a nightmare. Some files have different fps, and others different ratios.  I wanted to know if mp4 is the format I should be using, or if there is a better, easy to use format for concatenation. Time isn't an issue, I simply need a relatively high-quality format that concatenates under most circumstances.  If this doesn't exist, any suggestions on how to deal with massively varying properties of mp4 files (I'm not entirely sure of what can differ aside from fps and ratio between videos that may cause a problem) would be great.  I am using ffmpeg to try and concatenate the files. First I tried to use the demuxer, and then the concat filter, however I find the concat filter very daunting and am completely at a loss as to how to use it.  Each video has audio, some have still images while others have moving.
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Given HDD 1TB with a two partitions: one is small ~24GB (for Ubuntu) and all the rest is the second partition with about 10% occupied space for multimedia files.  I want to duplicate it as fast as possible. I boot from USB stick. The second disk is /dev/sdb.  sfdisk -d /dev/sda &gt; a sfdisk /dev/sdb &lt; a   Then I copy bytewise the small partition:  dd if=/dev/sda1 of=/dev/sdb1 bs=4M status=progress   It takes about two minutes. Then I want to copy in optimal manner contents of the second partition. Just filesystem w/ file attributes:  rsync -avHAX /media/ubuntu/sda2dir /media/ubuntu/sdb2dir   After that I tried to boot from second HDD and can't.  How to copy MBR and other crucial information?  dd if=/dev/sda of=/dev/sdb takes about 1h20m for 1TB HDD. It is not acceptable. And seems also not works.
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I know MOVs inside surge protectors degrade over time, but I also see manufacturers putting notes on the box that the protection warranty is void if I daisy-chain surge protectors.  So questions:   Is there an estimate of what the life of a MOV is if:  i. it has never faced a surge before?  ii. it has faced some surges before? I'm buying surge protectors with indicators showing the effectiveness of the surge protection: how do they work?  How does that indicator know if the surge protection is still effective? Why do manufacturers discourage daisy-chaining of surge protectors?   I'm assuming most off-the-shelf/commercial "computer"-grade surge protectors use MOVs.  I was interested in finding out if the MOVs are connected in parallel to the AC output of the surge protectors?  If so, how do MOVs connected in parallel interact (something like connecting resistors or capacitors in parallel or series changes their values)?
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I know it's kind of a dead / dying technology, but I was wondering what stops a CD-R from being rewritten like a CD-RW.   Is it some sort of firmware on the disc, essentially in place to make people buy more CDs?  Or is there a more technical reason, ie. CDs store their data magnetically (correct?) but CD-Rs have less magnetism, so once it has been written to, that's it? (Sorry if that's completely wrong; I have no idea how CDs work.)
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The  recommends that images have Copy-On-Write disabled on the directory when using btfs.  I do see that it would be a good idea if you had a lot of file read/writes.   question explores this idea.  I know that VMWare will grow into different files and will write snapshots out which could be problematic when using Copy-On-Write.  For QEMU the file is left open for the VMs existance so there is a potential problem in the write after the VM is shutdown, but I would see slow I/O after a VM is shutdown not being an issue.  What pitfalls would I be avoiding by performing this step for QEMU.    Additionally: I have assumed that the image is raw for this question.  Is there a possible stability issue as qcow2 already has copy-on write.
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I was wondering how low you could go with hardware that would still be able to smoothly run HD movies.  My current plan is around $215 CAD w/o a hard drive: Intel Pentium 4 @ 3.2 GHz - 1GB DDR/SDRAM - 512MB X1600 Pro AGP - 350W PSU - ECS P4VXASD2+ - Bluray/DVD-RW drive.  As for the hard drive, could I just get a 7200RPM IDE HDD? Also, I'm planning on installing XP Pro SP3, unless Ubuntu somehow has an advantage.  I'm not wanting this to be a media center only computer... just want it to be a normal computer with just enough oomph to play HD movies.  Thanks in advance.  EDIT1: Forgot to mention that the Bluray/DVD-RW drive is SATA, but I was planning on getting an SATA-IDE adapter or a PCI card with SATA.  EDIT2: Oh yes... if I get a PCI card with SATA, would you then recommend I use an SATA hard drive as well? That would leave all the IDE ports on the motherboard unused... is that a good idea?
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I'm familiar with what a BBWC (Battery-backed write cache) is intended to do - and previously used them in my servers even with good UPS. There are obvously failures it does not provide protection for. I'm curious to understand whether it actually offers any real benefit in practice.  (NB I'm specifically looking for responses from people who have BBWC and had crashes/failures and whether the BBWC helped recovery or not)  Update  After the feedback here, I'm increasingly skeptical as whether a BBWC adds any value.  To have any confidence about data integrity, the filesystem MUST know when data has been committed to non-volatile storage (not necessarily the disk - a point I'll come back to). It's worth noting that a lot of disks lie about when data has been committed to the disk (). While it seems reasonable to assume that disabling the on-disk cache might make the disks more honest, there's still no guarantee that this is the case either.  Due to the typcally large buffers in a BBWC, a barrier can require significantly more data to be commited to disk therefore causing delays on writes: the general advice is to disable barriers when using a non-volatile write back cache (and to disable on-disk caching). However this would appear to undermine the integrity of the write operation - just because more data is maintained in non-volatile storage does not mean that it will be more consistent. Indeed, arguably without demarcation between logical transactions there seems to be less opportunity to ensure consistency than otherwise.   If the BBWC were to acknowledge barriers at the point the data enters it's non-volatile storage (rather than being committed to disk) then it would appear to satisfy the data integrity requirement without a performance penalty - implying that barriers should still be enabled. However since these devices generally exhibit behaviour consistent with flushing the data to the physical device (significantly slower with barriers) and the widespread advice to disable barriers, they cannot therefore be behaving in this way. WHY NOT?  If the I/O in the OS is modelled as a series of streams then there is some scope to minimise the blocking effect of a write barrier when write caching is managed by the OS - since at this level only the logical transaction (a single stream) needs to be committed. On the other hand, a BBWC with no knowledge of which bits of data make up the transaction would have to commit its entire cache to disk. Whether the kernel/filesystems actually implement this in practice would require a lot more effort than I'm wiling to invest at the moment.  A combination of disks telling fibs about what has been committed and sudden loss of power undoubtedly leads to corruption - and with a Journalling or log structured filesystem which don't do a full fsck after an outage its unlikely that the corruption will be detected let alone an attempt made to repair it.   In terms of the modes of failure, in my experience most sudden power outages occur because of loss of mains power (easily mitigated with a UPS and managed shutdown). People pulling the wrong cable out of rack implies poor datacentre hygene (labelling and cable management). There are some types of sudden power loss event which are not prevented by a UPS - failure in the PSU or VRM a BBWC with barriers would provide data integrity in the event of a failure here, however how common are such events? Very rare judging by the lack of responses here.   Certainly moving the fault tolerance higher in the stack is significantly more expensive the a BBWC - however implementing a server as a cluster has lots of other benefits for performance and availability.  An alternative way to mitigate the impact of sudden power loss would be to implement a SAN - AoE makes this a practical proposition (I don't really see the point in iSCSI) but again there's a higher cost.
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To stupid people, like me, you would have thought overwriting each bit on a disk would render the data completely unrecoverable.  Why do disk wiping tools have the option for multiple passes, i.e. 3 or 5, even 7 and different methods?  Surely the first pass does the job?  My question - Is it just down to pure paranoia or should I be using multiple passes when wiping disks... and why?
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I've used dd to clone disks like this:   dd if=/dev/sdb of=/dev/sda bs=4096 conv=notrunc,noerror,sync   And it's always worked fine. Any and all docs on 'dd' take pains to remind you that the target disk must be the same size or bigger than the source.  Does that absolutely have to be true?   Now, I quite understand that if I clone to a smaller disk I can't expect any partitions that are even partially  'out of bounds' on the target to be intact.  However, knowing full well  that I'd need to edit my partitions on the target later, deleting the 'out of bounds' ones, could I still use 'dd' to make a brute force copy of the source up to the limits of the physical size of the target? Or would 'dd' reduce the target to a smoking pile of wreckage when it reached the limit of its size ;-)  BTW, researching this, I've seen recommended values for bs= of everything from bs=1024 up to bs=32M, what really is best?
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I hear both sides of the story. "Installing both discs will improve performance" or "Playing from the disc is best".  I've come across a few threads that say to install the play disc to a USB drive. Will the Xbox 360 even read from 2 different sources at once?   Someone please clear this up for me, for all of us.  Do I Install the second "play" disc or not, and why?
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While doing some photography reading, i came across some support for archiving photos, videos on SD Cards. The process looked like:   Fill up SD Card with DSLR Share/publish any choice items via the PC Physically archive the SD Card   I would contrast this with my own method:   Fill up SD Card with DSLR Move contents to PC's HDD to free up SD Card Archive data via traditional PC backup/archive mechanisms   While this makes good sense from a digital photography point of view, I wasn't sure how well it fit for standard PC archival. (This is why i post here instead of the photography stackexchange) Can anyone speak to the negatives of generic PC-based backup/archival via SD card?   Is there anything that would limit my ability to retrieve data later? Are there any environmental concerns (moisture, heat, sunlight, etc.) that could cause things to break down?   Edit 1 - in doing some more research, i see that SanDisk has a  product that is 100 year archival with (W)rite (O)nce (R)ead (M)any funtionality. What I didn't get was if that was available for purchase or the cost per GB.  Edit 2 - SD-WORM requires special readers/writers, and wouldn't be suitable.
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For what longest possible time it was possible to hold light in a closed volume with mirrored walls?   I would be most interested for results with empty volume but results with solid-state volume may be also interesting.
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Do you guys know how much time needs to pass until the data stored on a hard drive starts to degrade?   To keep the data intact for long periods of time, I heard you need to periodically rewrite it on the hard drive, like every 5 years or so. Is it true?
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I'm building a new computer over the summer. I'm fairly competent in computer hardware, and am thus building the computer from scratch. I have everything planned out, but I was wondering about RAID.  I  earlier, but now that it's pretty clear that RAID 1 isn't really that great, I think I'll go with cloud-backup instead of disk-redundancy. However, I still face a choice: use two 1 TB drives as two 1 TB drives, or combine them into a RAID 0 striped array.  Is there any performance gain at all? I know that if one drive dies, everything is gone, so is the performance gain worth it? I'm building a pretty advanced computer, with SLI video cards and a fast CPU, so I'm thinking RAID 0 would give me some good hard drive performance. From your experience, is RAID 0 viable?