Exploring WD Advanced Format drives

I’ve been playing with WD Green disks, trying to solve the 4,096-byte sector problem. To summarize, Western Digital have started to move from 512-byte sectors to 4,096-byte sectors in order to reduce overhead and thereby increase the amount of data that can be stored on the same amount of platters with the same density. These disks (specifically, the EARS and AARS series) emulate 512-byte sectors for compatibility with older BIOSes and operating systems, but the problem is that they report 512-byte logical and physical sectors instead of 512/4,096.

If the length of a write operation is not a multiple of 4,096, or it does not begin at an address divisible by 4,096, either the beginning or the end of the operation, or both, will cover only part of a sector. This requires the disk to do a read-modify-write operation, meaning that it has to read a complete 4,096-byte sector, update parts of it, and write it back. This is extremely inefficient, as I will demonstrate later. Continue reading “Exploring WD Advanced Format drives” »

Old history

I am the current maintainer of OpenSSH for FreeBSD, and have been since 2002. I am also the author and maintainer of the PAM implementation used by FreeBSD, and of several of the accompanying PAM modules. Finally, I was a member of the FreeBSD Security Team for several years, served as Assistant Security Officer and Acting Security Officer, and authored or co-authored around 20 security advisories between 2002 and 2004.

I have been asked to comment on SecurityFocus advisories 7467 and 7482, regarding timing attacks against certain versions of OpenSSH that were distributed with FreeBSD 4.x and 5.x releases.

The short version is that no FreeBSD 4.x or 5.x release was ever vulnerable. Read on for the long version. Continue reading “Old history” »

Ten years

That’s how long, to the day, I have been a FreeBSD committer.
Ten years seems like a long time when you write it down on paper, or say it out loud, or try to imagine who and where you will be in ten years’ time; but when I think back on my time as a FreeBSD committer, it’s hard to believe it’s really been that long.

The strangest part is seeing younger (or rather, more recently anointed) committers defer to me. I’m not the old tenured professor! I’m not the sage on the mountain! Look at phk, he’s the old fart, not me! I’m still a rookie! I practically haven’t done anything for the project! I mean, apart from libfetch, and pseudofs, and the PAM stack, and OpenSSH, and the Tinderbox, and stints as Bugmeister and Security Officer, and…

This is where my train of thoughts derails, when I realize how much I’ve actually done (although I don’t even come close to people like phk, jhb, or rwatson), and oh shit, it’s actually been ten years!

Update: when I told my wife about this, her immediate reaction was “and they say men can’t commit to anything…”