21,695 reputation
12449
bio website ripple.com
location Oakland, CA
age 45
visits member for 3 years, 4 months
seen 3 hours ago

I am Chief Cryptographer at Ripple Labs and one of the architects of the Ripple payment system.


Dec
16
comment HP Procurve 2920 VLANs with DHCP cannot ping
That doesn't make sense. If the server already has an IP address inside 192.168.x.0, it shouldn't need a route. And if it doesn't have an IP address inside 192.168.x.0, it shouldn't know how to reach 192.168.x.2 without a route that would also work for the rest of 192.168.x.0/24.
Dec
11
comment Swap 99% but regular memory fine
What is swappiness set to?
Dec
11
comment Swap 99% but regular memory fine
Right. It seems like his system is making a rational tradeoff. It doesn't have an awful lot of RAM, so it's moving rarely used stuff to swap to make more physical RAM available. The tradeoff is that when rarely used stuff is actually used, there's a performance hit. The benefit is that the most used stuff is faster.
Dec
8
comment Connect two mikrotik LAN
Don't bridge two IP networks through a pseudobridge. Pseudobriding is only suitable for bridging a single layer 2 device.
Dec
1
comment HP Procurve 2920 VLANs with DHCP cannot ping
To be clear, you are saying 192.168.1.1 cannot ping 192.168.0.1, even though both have the switch as their default gateway? Is that correct?
Dec
1
comment HP Procurve 2920 VLANs with DHCP cannot ping
Can the machines ping the switch's other addresses? Can 192.168.1.1 ping 192.168.0.2? Can 192.168.0.1 ping 192.168.1.2?
Nov
27
comment Software RAID 10 not any faster than s/w RAID 5 on Ubuntu 14.04 box, why?
@chutz Why do you think that makes any difference?
Nov
27
comment Software RAID 10 not any faster than s/w RAID 5 on Ubuntu 14.04 box, why?
@chutz He's not testing small random writes. But in any event, the same thing applies to RAID 10. If you change just one byte, it has to read the entire block containing that byte.
Nov
20
comment Setup network between 2 computers connected using wifi
You're getting downvotes because this is a site for professional network engineers to discuss problems they experience in professional system administration. Questions like "how can I connect two computers together" belong on different sites.
Nov
14
comment Do routers verify UDP and TCP checksums?
Are you asking what real world routers actually do? Or are you asking what is officially part of the definition of what a router does?
Nov
4
comment Would 6 SSD's in RAID 0 last longer than a single large SSD?
"To my understanding, the main factor for SSD's to fail is constant reading/writing to the drive." That's simply not true. While that's certainly a way SSDs can fail, it's extremely unlikely for a modern SSD to last long enough to reach write exhaustion with typical usage.
Nov
4
comment 3ware 9500 stopped showing up in Linux
If the data wasn't worth the minimal effort of backing up, it's surely not worth the major effort of recovery.
Nov
4
comment 3ware 9500 stopped showing up in Linux
With a system that old, I'd just replace the hardware and restore from a backup. It's very unlikely that troubleshooting or repairing hardware that's that old is going to be cost effective.
Nov
3
comment why online tools can not find my MX record?
When you say "on my server", what precisely do you mean?
Nov
1
comment TCP/UDP Small Package Size optimization
You kind of didn't tell us what your question is about. What software are you using? What hardware are you using? How are you measuring? What does your CPU load look like?
Oct
29
comment Server time won't remain set
There's absolutely no useful description of the problem here. Is it the timezone that won't stay set or the time? If the zone, what does it change to/from? If the time, does it stop? Jump forward? Always become off by the same amount? Or what?
Oct
21
comment Linux not freeing large disk cache when memory demand goes up
The problem is that without swap, overcommitting results in the OOM killer running and not overcommitting results in a system that can't launch processes. You need swap to make effective use of RAM.
Oct
20
comment Why in 64 bit machine not able to use whole free memory as disk cache. Facing sudden disk cache drop
Do you have an actual performance problem or is this purely a cosmetic issue?
Oct
20
comment Is it valid for a hostname to start with a digit?
Thank you, 3com.
Oct
20
comment How does my registrar (Namecheap) let me set up a CNAME record on the apex domain?
@tobek I tried to get an authoritative response and could not get one. Testing tools were unable to get one either. It happened to work when you tried it. The rules specifically prohibit it. Either you're happy with that or you're not. If you're looking for some kind of guarantee, you're not going to get it. It's not supposed to work.