4,790 reputation
11135
bio website mattdm.org
location Somerville, MA
age
visits member for 4 years
seen 13 hours ago

I'm the Fedora Project Leader. I work for Red Hat — and for the Fedora community at large! – but my posts here are all my own.

Previously, I was a sysadmin in the Academic Computing group at Harvard School of Engineering and Applied Sciences, and before that, I made Boston University Linux.


Feb
17
comment What is cloud computing?
See also: serverfault.com/questions/206703
Feb
8
comment Should I use GlusterFS as storage pool for KVM/Xen virtual machines?
What's the question here exactly?
Feb
8
comment I have a perl script that is supposed to run indefinitely. It's being killed… how do I determine who or what kills it?
Running out of memory? Check the logs for oom killer messages.
Feb
8
comment Is there a diff/merge utility to compare binary files and synchronize data bit-by-bit in either direction based on differences in binary data?
If the data is valuable enough to go to all that trouble, why not use ddrescue as intended? (And, in 20/20 hindsight, why isn't it backed up elsewhere?) ddrescue does what you want not by treating zeros as magical but by deciding to overwrite based on whether it got errors. (It'll never write out new bad-read zero blocks.)
Feb
8
comment Is there a diff/merge utility to compare binary files and synchronize data bit-by-bit in either direction based on differences in binary data?
I think you should change the subject of your question to reflect that you're not looking for a general-purpose tool to synchronize based on just any differences in binary data.
Feb
8
comment Is there a diff/merge utility to compare binary files and synchronize data bit-by-bit in either direction based on differences in binary data?
Yeah, rsync doesn't care about your special-case.
Feb
8
comment Is there a diff/merge utility to compare binary files and synchronize data bit-by-bit in either direction based on differences in binary data?
So, really, the answer here is "use the ddrescue version". And, if your bad source drive is still functional at all, you can run ddrescue on it again with the same output file as many times as you want until you've extracted the most possible data.
Feb
8
comment Is there a diff/merge utility to compare binary files and synchronize data bit-by-bit in either direction based on differences in binary data?
I think it's very likely, given what you've described, that such an overlap is very common in your destinations. In fact, it's most likely that ddrescue has gotten everything the dd copy does plus, possibly more hopefully more correct data which dd just gave up on.
Feb
8
comment Is there a diff/merge utility to compare binary files and synchronize data bit-by-bit in either direction based on differences in binary data?
@purefusion -- you've got a very special case where the only errors you expect are zeroed-out blocks. I don't think any existing programs are built to deal with this, since it's such a narrow problem. But even if you do make or find something, what are you going to do about overlapping bad areas from your two sources?
Feb
8
comment Is there a diff/merge utility to compare binary files and synchronize data bit-by-bit in either direction based on differences in binary data?
Rsync does, in fact, use an intelligent binary-diff algorithm, although it works on a block basis rather than bit-by-bit. rsync.samba.org/tech_report/node2.html
Feb
8
comment What is consuming so much memory?
40 × about 20mb each = most of your RAM right there.
Feb
8
comment What is consuming so much memory?
2) /etc/fstab, probably. Again, really a whole separate question, and probably best on unix.stackexchange.com
Feb
8
comment What is consuming so much memory?
1) Look in your apache configuration, /etc/httpd/conf/httpd.conf. Configuring that properly is actually a whole 'nuther question.
Feb
8
comment Which motherboards support ECC RAM and USB 3.0?
Honestly, if you want it to be highly reliable, what you do is: 1) buy more than one and set them up in a HA configuration and 2) don't piece it together yourself; buy from a vendor who will fix it in N hours if it fails.
Feb
8
comment RHEL: Errata Explained
Okay, I see what you are asking. The packages are named like this: name-version-packagerelease. The package release will always (by policy) increment when the contents change.
Feb
8
comment RHEL: Errata Explained
@drewrockshard: uh, what? If you already have an older version of the same package, this is what you need. If you have that version already, you know you're covered (unless there's a newer update). If you don't have that package at all, you don't need to be worried.
Feb
7
comment How can I find all of the domain names owned by a company?
No I'm not. Really.
Feb
6
comment Why a 15-second delay when getting a page?
Sure. But "at some point" isn't very much information. Did it happen every time? You add now that it was consistent, but was it consistent for two minutes or over the course of days? Where were you connecting from? Was it slow from elsewhere? And so on. You may feel like you have good-enough answers to these questions, but really, if you're using very cheap hosting, you everything in a very neat package. That's one of the hidden costs of such a cheap service.
Feb
6
comment Why a 15-second delay when getting a page?
Setting up your own server is not, in fact, $0 per month.
Feb
6
comment MySQL reserves too much RAM
So, clearly it needs more memory than 65536k to start.