10,400 reputation
1257130
bio website stefanco.com
location Berkeley, CA
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visits member for 5 years, 1 month
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profile for Stefan Lasiewski on Stack Exchange, a network of free, community-driven Q&A sites
Stefan Lasiewski

Daddy, Linux Guy, Bicyclist, Tinkerer, Fixer & Breaker of things.

I work as a Senior Server Team Engineer at the National Energy Research Scientific Computing Center (NERSC) Division at Lawrence Berkeley National Laboratory (LBNL) in Berkeley, CA.

Father of 3 cute children. Yes I'm a sysadmin and a parent.

Heavy user of CentOS, RHEL & FreeBSD for production services at work. I also run Ubuntu at home, for the simplicity. I'm a fan of Apache HTTP Server, Nagios & Cacti.

Original proposer of unix.stackexchange.com (Yes, this proposal predated askubuntu.com, and I wish they would have merged with the Unix proposal.).


Mar
26
comment SSH-forwarded X11 display from Linux to Mac lost after some time
This does explain why the problem happens, but some reasoning would be helpful.
Mar
26
comment There is a kernel panic after every few months or weeks, with qemu-kvm tainted, VMs can't run. The machine needs to be rebooted
CentOS 6.4 was released 2 years ago. CentOS 6.5 was released over a year ago. Many many bugs have been fixed since then, including a number of important security bugs.
Mar
23
comment How can I validate a ZFS snapshot image residing on a backup system?
Glad I could help. ZFS is a great filesystem, but finding good examples outside of the Solaris docs can be hard.
Mar
18
comment Seconds_behind_master value keeps on increasing in MySQL replication slave
MySQL 5.0 reached it's end-of-life some time ago, and the latest MySQL 5.0 release is 5.0.96 (you have MySQL 5.0.77). Many replication bugs have been fixed since MySQL 5.0.77, and replication performance has improved quite a bit since even MySQL 5.1. There area many reasons for MySQL replication delays in older versions of MySQL.
Mar
10
comment freebsd cannot start mysql for the first time
The permissions 1777 are way too permissive and should only be used temporarily, and should generally be avoided. Leaving those in place for a long time is a security problem.
Jan
27
comment Linux tool/command to check file system performance
Running dd ... && sync has the advantage that it works on multiple operating systems, beyond just GNU/Linux.
Jan
26
comment Can OpenSSL be used to debug an SSL connection to a MySQL server?
Hm, I suppose the behavior I'm talking about is how STARTTLS works, according to en.wikipedia.org/wiki/STARTTLS .
Jan
23
comment Google apps won't let go of my email after canceling account
Remember -- at some point, you modified your DNS records to use Google. Undo that step.
Jan
23
comment Linux CLI command for ~“what is this machine”?
GNU/Linux doesn't provide a single, unified "standard command" to describe a server. facter is one of the most commonly used alternatives, however.
Jan
22
comment Why is Linux kdump not writing to /var/crash?
No I do not have a watchdog rebooting the machine. Turns out that the LSI controller + Samsung SSDs are periodically freezing for reasons that we don't totally understand.
Jan
19
comment Why doesn't Kosovo have its own ccTLD yet?
Oh I never said it was simple. But it's interesting.
Jan
19
comment Why doesn't Kosovo have its own ccTLD yet?
A ccTLD isn't always associated with a real-world political entity. The domain for the former Soviet Union still exists as .su. nic.su/dns/domain/su.html
Jan
16
comment How to generate a Self Signed SSL Certificate bound to IP address?
Your browser will still complain due to a lack of trust with any self-signed certificate. "self signed" mean's that the certificate was not signed by any trusted Certificate Authority, and the browser will not trust it by default.
Jan
14
comment IO tasks easily starve eachother on 3Ware 9650SE
A broken disk shouldn't lead to a state of 'initializing' it should lead to a state of 'repairing'.
Jan
14
comment IO tasks easily starve eachother on 3Ware 9650SE
Also, I believe the 3ware 9650SE cards were End-of-Life'd in 2013. Your card is quite old.
Jan
14
comment IO tasks easily starve eachother on 3Ware 9650SE
RAID6 is very slow (RAID10 is faster then RAID5/6 & is generally best for VMs, databases and other I/O sensitive applications), and most 2TB drives are also slow as they are stuck at 7200RPM, and your SATA interface is slow compared to SAS or Nearline-SAS Given that combination of slowness, that array will be slow to perform under for any I/O-sensitive task. The RAID6 array is currently 'initializing' which uses a high amount of I/O and normally only happens when an array is new and them performance is going to be bad until that initialization is complete. Did you put VMs on a brand new array?
Jan
12
comment Are Google Apps implicitly DDoS protected?
Any sufficiently large target like Google are frequently attacked by an elaborate array of DDoS attacks, some of which happen constantly. These elaborate attacks require elaborate monitoring and defenses. Google's reputation is harmed every time there is a successful attack, and thus they dedicate quite a few resources to their monitoring and defense. The specific tools are generally kept secret, and are changing frequently. Look for some of the videos given by the technical managers of the Google Site Reliability teams, Secops and Netops teams.
Jan
3
comment Update Docker container without downtime
All in all, this sounds like how one would update physical servers and physical loadbalancers as well.
Jan
2
comment What is a ToD server, “Time of Day” (Not NTP)
My older question has some information about this also: serverfault.com/questions/156715/…
Dec
30
comment Recovering a RAID5 with 2 disks out of the array
If the 2 disks are simply offline due to a bug, and if the data on the disks has not changed since the array failed, it might be possible to online the disks and recover the array.