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I have a system that runs windows via a USB stick (it's a proprietary machine). This type of machine is commonly powered off by 'pulling the plug'. There is no way around it, that is how it is operated.
We occasionally have drive corruption on the USB stick, or at least corruption in the directory that we write things into. Is there really any software solution to get around this problem other than 'write as little/infrequently as possible'?
It's a windows machine and the applications that write are typically written in Java/C# if that is useful to anyone. The corruption typically shows up as a write directory or the parent of a write directory that can no longer be accessed due to the corruption. The only way to deal with it is to delete it via command line and start over.
Is there any way to programmatically deal with such a scenario, to perhaps restore a previous state of the memory as opposed to deleting and starting anew?
I don't feel as though there is any way to prevent this type of thing from happening given our current design. If you do enough writes and keep pulling the plug you are eventually going to get a corruption and that's just facts. Especially in this design. Even if the backup batteries are charged, if the software doesn't shutdown gracefully within the battery's discharge time, the corruptions could still occur. Not to mention as gravitymixes said above its going to damage hardware eventually which we have seen before.
A system redesign needs to considered for this project as a whole. Some type of networked solution comes to mind immediately where data is sent off the volatile machine to be logged on a machine with a more reliable power source over a reliable network connection with writing to the disk on the actual volatile machine as a last ditch effort if network comms are not reliable at a given point in time (backfill). I feel like this would increase hardware life as well. Of course the problem of network reliability then becomes your problem.
So, I'm looking into Permanent DOS attacks for a class, and I'm having a hard time coming up with concrete examples. There's a lot of information about Phlashing (flashing firmware to either brick the device, or put malicious firmware in its place, for those of you who don't know the term) but I'd like to have a broader set of examples.
That being said, there has to be a way to write code that will do something like wear out disk arms, right? Something that will have the disk seek to the end of the disk, then back to the front, on and on. Anyone have an example of how that would be accomplished? Is there some way to specify where to track to on a disk in C (similar to traversing to a certain point in a file, but for the entire HDD!)? If not, I guess there's always trying to force a file's location on the disk... which seems like less fun trying to accomplish. Again, can you do something like that programmatically?
If anyone has any insight into these types of attacks, or any good resources for me to check into, I'd appreciate it. Maybe you read a story about it on Slashdot a few years back? Let me know! The more info I can gather, the less likely I'll be forced to kill time during my talk by bricking my router in the class :) I'm not made of money OR routers!
Seems like these would primarily be limited to physical attacks and social engineering ("To enable your computer's hidden turbo function, remove the cover and pry this part). But:
Adjust screen refresh rates to insane values to blow older CRTs
Monkey with ACPI fan, charge, or battery controls if possible to cause overheating or battery failure.
Overwrite every rewritable storage device of every kind attached to any bus. Discover and overwrite any IDE, USB, etc... device you know the flash updater details for.
Of course nothing is permanent. You can replace the hard drive, BIOS chips, CPU, motherboard, memory, etc...
Although it is mostly fictional, the halt and catch fire operation would be a very convenient and permanent DOS attack.
Steve Gibson (google his name) has a paper he wrote a few years back about protocol-level vulnerabilities in TCP/IP. Some of it is still pertinent today.
Socially engineer the power company or ISP to turn off service at the location in question.
Many devices in the computer today have their own firmwares, including but not limited to CPU, DVD, HDD, VGA, motherboard (BIOS) etc. Most of these devices also have a way of updating their respective firmwares. Which can also be used to brick them pretty efficiently. Although this does require an individual approach to every device, often using privileged instructions and undocumented interfaces.
It's possible for a virus to do this. I seem to recall an actual virus doing this back in the day, but can't find anything to back that up.
I was able to find an article where the author has a conversation with the VP from Western Digital wherein he states a program could potentially access a hard drive's firmware causing such a DOS attack:
There are back doors if you will that allow us to get into places that the operating system can't go through the IDE connector
There used to be a few viruses that could cause old CRT monitors to break. They could cause invalid sync signals out the VGA point that would be too high in frequency for the video sweep. I also remember a few that would use bad sector flagging to draw images on the old versions of Scandisk (we are talking early 90’s or older.) I don't remember and of the names or have any references, but they used to be quite annoying.
Fortunately better circuits, memory protection, API abstraction have made such attacked very difficult to impossible.
Our network team is thinking of setting up a virtual desktop environment (via Windows 2008 virtual host) for each developer.
So we are going to have dumb terminals/laptops and should be using the virtual desktops for all of our work.
Ours is a Microsoft shop and we work with all versions of .net framework. Not having the development environments on the laptops is making the team uncomfortable.
Are there any potential problems with that kind of setup? Is there any reason to be worried about this setup?
Unless there's a very good development-oriented reason for doing this, I'd say don't.
Your developers are going to work best in an environment they want to work in. Unless your developers are the ones suggesting it and pushing for it, you shouldn't be instituting radical changes in their work environments without very good reasons.
I personally am not at all a fan of remote virtualized instances for development work, either. They're often slower, you have to deal with network issues and latency, you often don't have as much control as you would on your own machine. The list goes on and on, and little things add up to create major annoyances.
What happens when the network goes down? Are your dev's just supposed to sit on their hands? Or maybe they could bring cards and play real solitare...
Seriously, though, Unless you have virtual 100% network uptime, and your dev's never work off-site (say, from home) I'm on the "this is a Bad Idea" side.
One option is to get rid of your network team.
Seriously though, I have worked with this same type of setup through VMWare and it wasn't much fun. The only reason why I did it was because my boss thought it might be worth a try. Since I was newly hired, I didn't object. However, after several months of programming this way, I told him that I preferred to have my development studio on my machine and he agreed.
First, the graphical interface isn't really clear with a virtual workstation since it's sending images over the network rather than having your video card's graphical driver render the image. Constant viewing of this gave me a headache.
Secondly, any install of components or tools required the network administrator's help which meant I had to hurry up and wait.
Third, your computer is going to process one application faster than your server is going to process many apps and besides that, it has to send the rendered image over the network. It doesn't sound like it slows you down but it does. Again, hurry up and wait.
Fourth, this may be specific to VMWare but the virtual disk size was fixed to 4GB which to my network guy seemed to think it was enough. This filled up rather quickly. In order for me to expand the drive, I had to wait for the network admin to run partition magic on my drive which screwed it up and I had to have him rebuild my installation.
There are several more reasons but I would strongly encourage you to protest if you can. Your company is probably trying to impliment this because it's a new fad and it can be a way for them to save money. However, your productivity time will be wasted and that needs to be considered as a cost.
Bad Idea. You're taking the most critical tool in your developers' arsenal and making it run much, much, much slower than it needs to, and introducing several critical dependencies along the way.
It's good if you ever have to develop on-site, you can move your dev environment to a laptop and hit the road.
I could see it being required for some highly confidential multiple client work - there is a proof that you didn't leak any test data or debug files from one customer to another.
Down sides:
Few VMs support multiple monitors - without multiple monitors you can't be a productive developer.
Only virtualbox 3 gets close to being able to develop for opengl/activeX on a VM.
In my experience Virtual environments are ideal for test environments (for testing deployments) and not development environments. They are great as a blank slate / clean sheet for testing. I think the risk of alienating your developers is high if you pursue this route. Developers should have all the best tools at their disposal, i.e. high spec laptop / desktop, this keeps morale and productivity high.
Going down this route precludes any home-working which may or may not be an issue. Virtual environments are by their nature slower than dedicated environments, you may also have issues with multiple monitor setups on a VM.
If you go that route, make sure you bench the system aggressively before any serious commitment.
My experience of remote desktops is that it's ok for occasional use, but seldom sufficient for intensive computations and compilation typical of development work, especially at crunch time when everyone needs resources at the same time.
Not sure if that will affect you, but both VMWare and Virtual PC work very slow when viewed via Remote Desktop. For some reason Radmin (http://www.radmin.com/ ) does a much better job.
I regularly work with remote development environments and it is OK (although it takes some time to get used to keep track in which system you're working at the moment ;) ) - but most of the time I'm alone on the system.
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I make extensive use of source control for anything that relates to a project I'm working on (source, docs etc.) and I've never lost anything that way.
However, I have had two or three crashes (spread over the last 4 years) on my development machine that forced me to reinstall my system and reconfigure my apps (eclipse, vim, Firefox, etc.). For weeks after reinstalling, I was missing one little app or another, some PHP or Python module wasn't there, stuff like that.
While this is not fatal, it's very annoying and sucks up time. Because it seemed so rare, I didn't bother about an actual solution, but meanwhile I've developed a mindset where I just don't want stuff like that happening anymore.
So, what are good backup solutions for a development machine? I've read this very similar question, but that guy really wants something different than me.
What I want is to have spare harddrives on the shelf and reduce my recovery time after a crash to something like an hour or less.
Thinking about this, I figured there might also be a way to use the backup mechanism for keeping two or more dev workstations in sync, so I can continue work at a different PC anytime.
EDIT: I should've mentioned that
I'm running Linux
I want incremental backup, so that it's cheap to do it frequently (once or twice a day)
RAID is good, but I'm on a laptop most of the time, no second hd in there, no E-SATA and I'm not sure about RAIDing to a USB drive: would that actually work?
I've seen sysadmins use rsync, has anybody had any experiences with that?
I would set up the machine how you like it and then image it. Then, you can set up rsync(or even SVN) to backup your homedir nightly/etc.
Then when your computer dies, you can reimage, and then redeploy your home dir.
The only problem would be upgraded/new software, but the only way to deal completely with that would be to do complete nightly backups of your drive(s).
Thanks, this sounds like a good suggestion. I think it should be possible to also update the image regularly (to get software updates / installs), but maybe not that often. E. g. I could boot the image in a VM and perform a global package update or something.
Hanno
You could create an image of your workstation after you've installed & configured everything. Then when your computer crashes, you can just restore the image.
A (big) downside to this, is that you won't have any updates or changes you've made since you created the image.
Cobian Backup is a reliable backup system for Windows that will perform scheduled backups to an external drive.
You could create a hard drive image. Restoring from a backup image restores everything to the exact state that it was at the time you took the image.
Or you could create an installer that installs just about everything needed.
Since you expressed interest in rsync, here's an article that covers how to make a bootable backup image via rsync for Debian Linux:
http://www.debian-administration.org/articles/575
Rsync is fast and easy for local and network syncing and is by nature incremental.
You can use RAID-1 for that. It’s the synchronize type, not the backup type.
I use RAID mirroring in conjunction with an external hard drive using Vista's system backup utility to backup the entire machine. That way I can easily fix a hard drive failure, but in the event my system becomes corrupted, I can restore from the E-SATA drive (which I only connect for backup).
Full disclosure: I've never had to restore the backup, so it's kind of like the airbag in your car; hopefully it works when you need it, but there's no way to be sure. Also, the backup process is manual (it can be automated) so I'm only as safe as the last backup.
You can use the linux "dd" command line utility to clone a hard drive.
Just boot from a linux cd, clone or restore your drive and reboot.
It works great for Windows/Mac drives too.
This will clone partition 1 of the first hard drive (/dev/sda) to partition 1 of the second drive (/dev/sdb)
dd if=/dev/sda1 of=/dev/sdb1
This will clone partition 1 of the first hard drive to a FILE on the second drive.
dd if=/dev/sda1 of=/media/drive2/backup/2009-02-25.iso
Simply swap the values for if= and of= to restore the drive.
If you boot from the Ubuntu live CD it will automount your USB drives making it easy to perform the backup/restore with external drive(s).
CAUTION: Verify the identity of your drives BEFORE running the above commands. It's easy to overwrite the wrong drive if you not careful.
Guess this is not exactly what you are looking for, but I just document all what I install and configure on a machine. Google Docs lets me do this from anywhere, and keeps the document intact when the machine crashes.
A good step by step document usually reduces the recovery time to one day or so
If you use a Mac, just plug in an external hard drive and Time Machine will do the rest, creating a complete image of your machine on the schedule you set. I restored from a Time Machine image when I swapped out the hard drive in my MacBook Pro and it worked like a charm.
One other option that a couple of guys use at my company is to have their development environment on a large Linux server. They just use their local machines to run an NX client to access the remote desktop (NX is much faster than VNC) - this has the advantages of fast performance, automatic backup of their files on the server, and the fact that they're developing on the same hardware that our customers use.
No matter what solution you use, it is always a good idea to have a secondary backup, too. Secondary backup should be off-site and include your essential work (source code, important docs). In case something happens to your main site (fire at the office, somebody breaks in and steals all your hardware, etc.), you would still be able to recover, eventually.
There are many online backup solutions. You could just get a remote storage at a reliable provider (e.g. Amazon S3) and sync your work on a daily basis. The solution depends on the type of access you can get, but rsync is probably the tool you would use for that.
I've got a machine I'm going to be using for development, and it has two 7200 RPM 160 GB SATA HDs in it.
The information I've found on the net so far seems to be a bit conflicted about which things (OS, Swap files, Programs, Solution/Source code/Other data) I should be installing on how many partitions on which drives to get the most benefit from this situation.
Some people suggest having a separate partition for the OS and/or Swap, some don't bother. Some people say the programs should be on the same physical drive as the OS with the data on the other, some the other way around. Same with the Swap and the OS.
I'm going to be installing Vista 64 bit as my OS and regularly using Visual Studio 2008, VMWare Workstation, SQL Server management studio, etc (pretty standard dev tools).
So I'm asking you--how would you do it?
If the drives support RAID configurations in your BIOS, you should do one of the following:
RAID 1 (Mirror) - Since this is a dev machine this will give you the fault tolerance and peace of mind that your code is safe (and the environment since they are such a pain to put together). You get better performance on reads because it can read from both/either drive. You don't get any performance boost on writes though.
RAID 0 - No fault tolerance here, but this is the fastest configuration because you read and write off both drives. Great if you just want as fast as possible performance and you know your code is safe elsewhere (source control) anyway.
Don't worry about mutiple partitions or OS/Data configs because on a dev machine you sort of need it all anyway and you shouldn't be running heavy multi-user databases or anything anyway (like a server).
If your BIOS doesn't support RAID configurations, however, then you might consider doing the OS/Data split over the two drives just to balance out their use (but as you mentioned, keep the programs on the system drive because it will help with caching). Up to you where to put the swap file (OS will give you dump files, but the data drive is probably less utilized).
If they're both going through the same disk controller, there's not going to be much difference performance-wise no matter which way you do it; if you're going to be doing lots of VM's, I would split one drive for OS and swap / Programs and Data, then keep all the VM's on the other drive.
Having all the VM's on an independant drive would let you move that drive to another machine seamlessly if the host fails, or if you upgrade.
Mark one drive as being your warehouse, put all of your source code, data, assets, etc. on there and back it up regularly. You'll want this to be stable and easy to recover. You can even switch My Documents to live here if wanted.
The other drive should contain the OS, drivers, and all applications. This makes it easy and secure to wipe the drive and reinstall the OS every 18-24 months as you tend to have to do with Windows.
If you want to improve performance, some say put the swap on the warehouse drive. This will increase OS performance, but will decrease the life of the drive.
In reality it all depends on your goals. If you need more performance then you even out the activity level. If you need more security then you use RAID and mirror it. My mix provides for easy maintenance with a reasonable level of data security and minimal bit rot problems.
Your most active files will be the registry, page file, and running applications. If you're doing lots of data crunching then those files will be very active as well.
I would suggest if 160gb total capacity will cover your needs (plenty of space for OS, Applications and source code, just depends on what else you plan to put on it), then you should mirror the drives in a RAID 1 unless you will have a server that data is backed up to, an external hard drive, an online backup solution, or some other means of keeping a copy of data on more then one physical drive.
If you need to use all of the drive capacity, I would suggest using the first drive for OS and Applications and second drive for data. Purely for the fact of, if you change computers at some point, the OS on the first drive doesn't do you much good and most Applications would have to be reinstalled, but you could take the entire data drive with you.
As for dividing off the OS, a big downfall of this is not giving the partition enough space and eventually you may need to use partitioning software to steal some space from the other partition on the drive. It never seems to fail that you allocate a certain amount of space for the OS partition, right after install you have several gigs free space so you think you are fine, but as time goes by, things build up on that partition and you run out of space.
With that in mind, I still typically do use an OS partition as it is useful when reloading a system, you can format that partition blowing away the OS but keep the rest of your data. Ways to keep the space build up from happening too fast is change the location of your my documents folder, change environment variables for items such as temp and tmp. However, there are some things that just refuse to put their data anywhere besides on the system partition. I used to use 10gb, these days I go for 20gb.
Dividing your swap space can be useful for keeping drive fragmentation down when letting your swap file grow and shrink as needed. Again this is an issue though of guessing how much swap you need. This will depend a lot on the amount of memory you have and how much stuff you will be running at one time.
For the posters suggesting RAID - it's probably OK at 160GB, but I'd hesitate for anything larger. Soft errors in the drives reduce the overall reliability of the RAID. See these articles for the details:
http://alumnit.ca/~apenwarr/log/?m=200809#08
http://permabit.wordpress.com/2008/08/20/are-fibre-channel-and-scsi-drives-more-reliable/
You can't believe everything you read on the internet, but the reasoning makes sense to me.
Sorry I wasn't actually able to answer your question.
I usually run a box with two drives. One for the OS, swap, typical programs and applications, and one for VMs, "big" apps (e.g., Adobe CS suite, anything that hits the disk a lot on startup, basically).
But I also run a cheap fileserver (just an old machine with a coupla hundred gigs of disk space in RAID1), that I use to store anything related to my various projects. I find this is a much nicer solution than storing everything on my main dev box, doesn't cost much, gives me somewhere to run a webserver, my personal version control, etc.
Although I admit, it really isn't doing much I couldn't do on my machine. I find it's a nice solution as it helps prevent me from spreading stuff around my workstation's filesystem at random by forcing me to keep all my work in one place where it can be easily backed up, copied elsewhere, etc. I can leave it on all night without huge power bills (it uses <50W under load) so it can back itself up to a remote site with a little script, I can connect to it from outside via SSH (so I can always SCP anything I need).
But really the most important benefit is that I store nothing of any value on my workstation box (at least nothing that isn't also on the server). That means if it breaks, or if I want to use my laptop, etc. everything is always accessible.
I would put the OS and all the applications on the first disk (1 partition). Then, put the data from the SQL server (and any other overflow data) on the second disk (1 partition). This is how I'd set up a machine without any other details about what you're building. Also make sure you have a backup so you don't lose work. It might even be worth it to mirror the two drives (if you have RAID capability) so you don't lose any progress if/when one of them fails. Also, backup to an external disk daily. The RAID won't save you when you accidentally delete the wrong thing.
In general I'd try to split up things that are going to be doing a lot of I/O (such as if you have autosave on VS going off fairly frequently) Think of it as sort of I/O multithreading
I've observed significant speedups by putting my virtual machines on a separate disk. Whenever Windows is doing something stupid in the VM (e.g., indexing yet again), it doesn't thrash my Mac's disk quite so badly.
Another issue is that many tools (Visual Studio comes to mind) break in frustrating ways when bits of them are on the non-primary disk.
Use your second disk for big random things.