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  • 0 posts edited
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  • 241 votes cast
May
13
comment Preventing theft of data on remotely deployed servers exposed to physical access
@André: Not exactly easily, but yes. Even systems like the Xbox 360 got cracked. Not sure about the Xbone.
Feb
24
comment Linux: ps command's output is randomly different than expected, can you find the reason?
It works for me. Tested on Ubuntu 14 LTS and Fedora 21. Maybe CentOS 6 is just too old. I didn't realize it was a new thing.
Feb
24
comment Linux: ps command's output is randomly different than expected, can you find the reason?
Instead of etime use etimes. Put the s on the end.
Jan
19
comment Although 80 and 443 are system ports, how are most web servers able to bind to them anyway?
On Linux you can also apply CAP_NET_BIND_SERVICE capability to the program or you can use iptables to redirect a system port to a regular port.
Jan
5
comment Linux: ps command's output is randomly different than expected, can you find the reason?
You have your answer. What you didn't ask was how to do this better. Use etimes to get seconds. Then you have no weird parsing of the time to do.
Dec
5
comment Linux - Is there a way to prevent/protect a file from being deleted even by root?
Taking this a bit further, you can use squashfs or cramfs which are compressed and read-only. It needs a special tool to build the filesystem.
Nov
22
comment Write caching in linux
I am not sure about Windows but Linux may defer non-sync writes up to the sysadmin's configured time. Defaults are 5 or 60 seconds depending on the filesystem.
Nov
22
comment Would the data on the RAID Card Cache and Drive Cache be lost when a kernel panic happens?
The machine's power distribution board or motherboard might also fail. Although personally I've seen more RAID card failures.
Nov
18
comment TCP Dump, cannot understand these 4 lines?
That can also be caused by a messed up router/firewall. See lwn.net/Articles/92727
May
22
comment Packet loss on between firewall and uplink?
I've seen these intermittent problems caused by either bad cable or failing ports combined with link autonegotiation. It glitches and thinks it is 10Mbit half, for example. It might work fine forever just by forcing the connection type. Remember to do both ends.
Apr
15
comment 4TB drives using an ARC-1231 controller?
@StefanLasiewski: A new RAID controller is as likely to fail as an older one. If really new, even more likely.
Apr
9
comment Why is 1 of my 24 CPUs Pegged at 100%?
Couldn't that also be a driver bug or a piece of bad hardware interacting with a driver with no error recovery? Or maybe software calling into the kernel in a tight loop.
Mar
31
comment Force edit txt file that is in use windows
I remember seeing programs that would forcably break file locks. I believe they did it by attaching to each process with the lock and closing the file handle from inside the process.
Feb
16
comment Tuning Linux disk caching behaviour for maximum throughput
@PeterMeyer: Even if you have a lot of RAM it is still a mistake to wait for writes to start. The only time that makes any sense at all is if you are going to be editing or deleting files (like a temporary file) before it would get to disk. A backup does not do that. You want to start background writes as soon as possible. Set your background_ratio to 1 or 2.
Feb
15
comment Tuning Linux disk caching behaviour for maximum throughput
Wouldn't it make more sense to start writing as soon as possible? Otherwise it reaches the maximum buffer size and suddenly comes to a halt. If it was writing all along it gives you more time.
Dec
13
comment How do I speed up and cache mmap file access over NFS on Linux?
I added some info about proc mounts to the question.
Dec
13
comment How do I speed up and cache mmap file access over NFS on Linux?
@DavidSchwartz: Right. Since these are virtual systems there aren't any real local disks. It's all virtual. The "local disk" is a VMware image backed by iSCSI.
Dec
13
comment How do I speed up and cache mmap file access over NFS on Linux?
Sequential read/write runs at 80MB/s per second, so that part of the NFS tuning is okay.
Nov
30
comment In TCP/IP terms, how does a download speed limiter in an office work?
@TessellatingHeckler: The method that I like also enables the use of ECN which actually does tell the sending server to slow down without dropping packets. This method is to apply the rate limiter such as RED to packets leaving on the LAN interface, instead of trying to use an ingress filter on the WAN interface.
Nov
23
comment Networking Units: Not getting expected performance from 100Mb Ethernet
@MarkM: If you look at the reviews of NAS equipment, you will find that 40/20 MB/s is not an unusual speed.