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Solaris Express memory requirements [Feb. 7th, 2008|05:57 pm]
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I'm helping some folks at work debug a problem with NFSv4 on Solaris 10. I thought I would check if the same bug appeared in Solaris Express: Community Edition. I tried to install build 81 on an old Dell - a Pentium 4 machine with 512 MB of RAM. I was greeted with this lovely message:
This installer requires a minimum of 760 MB of physical memory to install. This system has 512 MB of physical memory. Exiting to shell.

You have got to be fucking kidding me.
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bus-powered eSATA ? [Jan. 14th, 2008|01:09 pm]
Bus-powered eSATA is in the works. I'm very glad to hear this, as I use external 2.5" drives heavily. The lack of bus-power was my main gripe with eSATA, and the one thing keeping me using FireWire drives. If a future eSATA port can provide enough power to run a 2.5" drive, I'll be one happy camper.
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Dell to offer Solaris 10/x86 [Nov. 14th, 2007|03:05 pm]
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I'm still in a little shock. Dell is now a reseller for Solaris 10.

More details here.

There's no list yet of which servers will have S10 as an option. But this is still a big boost for Solaris. It's good to see Sun doing well.
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Internet2 and IPv6 [Oct. 14th, 2007|01:04 pm]
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This makes me laugh:

$ dig ipv6.internet2.edu AAAA

; <<>> DiG 9.4.1-P1 <<>> AAAA ipv6.internet2.edu
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 23850
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;ipv6.internet2.edu. IN AAAA

;; ANSWER SECTION:
ipv6.internet2.edu. 7185 IN CNAME www.internet2.edu.

;; Query time: 3 msec
;; SERVER: 10.0.1.1#53(10.0.1.1)
;; WHEN: Sun Oct 14 13:03:16 2007
;; MSG SIZE rcvd: 54
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Has Linux gotten slower on the desktop? [Oct. 9th, 2007|02:34 pm]
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[music |Morrissey - Yes, I am Blind]

I'm about ready to pull my hair out because of how slow my FC 5 VM is. I've given is two 64-bit CPUs and 768 megs of RAM, and it's dragging to do even basic tasks, like open a terminal emulator. Using yum to install strace took nearly a minute (to parse some XML and yank down the bits from a mirror that's one router away).

Admittedly, I haven't used Linux in a desktop mode for several years (I'm only doing it here to test compatibility with something else). But I don't remember it being this sluggish. My XP SP2 VM (with identical config) is positively zippy in comparison. I wonder if anyone else is having this problem?
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ZFS' threading limits IO [Sep. 19th, 2007|01:40 pm]
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Ew.

I just found that in ZFS, each zpool only uses a single thread for raidz/z2 and checksum calculations. Frankly, I'm shocked that Sun made this implementation decision. I hope it gets fixed for S10U5.

ZFS compression used to be single-threaded, but that was fixed a while ago in Nevada, and in S10U4.

While ZFS has a great design, the implementation could use a lot of performance tuning.
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Linux software mirroring question [Sep. 15th, 2007|06:06 pm]
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I have a Linux question. Perhaps someone can help me.

I want to mirror two drives. For the life of me, I can't figure out how to do it without reinstalling the OS.

Let me elaborate. I inherited a CentOS 4.5 server with a single drive. It's using LVM with the LVM Physical Extents built directly on raw disk partitions. Herein lies the problem. At least historically, LVM has been unable to do mirroring itself. If you wanted to use LVM on a mirror, you had to first create Software RAID partitions on the drives, build a /dev/md device on those raw partitions, and then build LVM PEs on the /dev/md device.

Graphically, it looks like this:

filesystem ---> LVM ---> /dev/md ---> raw disk.

What a fragile, cumbersome thing is the Linux storage stack!

So here's the rub. I have this:

filesystem ---> LVM ---> raw disk.

How do I stick /dev/md in the middle of that? I asked around and was told by various Linux admins that the easiest way to do it would be to reinstall the OS and use the installer to redefine the partitions. Surely this can't be the case, I thought. There has to be a way to mirror a single disk without blowing away the system and starting over.

So I tried something. On a test machine, I added a second disk and created a "faulted" /dev/md mirror on it (a mirror with only one disk). I then added this /dev/md device into the LVM's volume group and did a pvmove from the original disk to the new disk. Note that this is against the pvmove man page, which explicitely states that moving physical extents on a mounted filesystem is "not recommended." (So much for the much ballyhooed value of an LVM).

I had intended to reboot off the new disk, then remove the old disk from the volume group, create the /dev/md partitions on it and attach it to the "faulted" mirror. I didn't get that far. I ended up with an unbootable mess of bits on my disks.

So much for that plan.

I've read that newer versions of LVM finally support mirroring. It even supports converting "linear" LVM into mirrored LVM with the lvconvert tool. Has anyone tried this? Given my previous experiences with LVM on Linux, I'm not too keen to try. Perhaps I should steal a spare blade and try another test.
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Opera 9.5 is looking pretty nice [Sep. 11th, 2007|10:08 am]
[music |Perry O'Neill - Kubik]

People say I complain too much. I probably do. I prefer to think of it as part of my charm :)

So I decided to say something nice. I've been running the Opera 9.5 alpha for several days, and I'm loving it. It's incredibly fast. I switched it to my default browser (from FF 2.0), and overall I'm not regretting it.

There are still a fair amount of glitches (with it being an alpha, after all), but I'm sure those will be ironed out by the time 9.5-final ships.
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An early look at probevue [Sep. 9th, 2007|05:17 pm]
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AIX 6 will have a dynamic instrumentation feature called probevue. There's been a lot of noise lately by people wanting to know how probevue compares to Sun's DTrace, the sine qua non of safe, scalable instrumentation.

The current beta of AIX 6 lacks probevue support. All we have are the man pages. Based on this limited data, I'm going to do the best I can to compare the two. Needless to say, since I haven't actually tried probevue, this comparison is rather superficial.

Based on the probevue man page, it appears that both DTrace and probevue have per-CPU tracing buffers which are periodically read by a userspace consumer. Both dtrace(1) and probevue allow the user to adjust the size of the buffers and the frequency with which they are read.

Both DTrace and probevue are programmable: DTrace has its D language; probevue has VUE scripts. There is nascent documentation on the VUE language. According to IBM, a more complete reference will be released shortly. Based on this early documentation, there are many similarites between D and VUE.

DTrace executes D scripts in a lightweight in-kernel virtual machine. It is unclear from IBM's documentation how probevue executes its VUE scripts.

Both languages work by specifying actions to be taken when certain probes fire. Execution of these actions can be further restricted with optional predicates. DTrace uses a four tuple to identify probes. probevue identifies probes with a three to six tuple.

Both languages have global, thread-local and clause-local variables. Both languages provide access to kernel global variables. Unlike DTrace, probevue requires that kernel global variables be declared inside a VUE script before it can be used. For example, in VUE, to access the kernel global variable lbolt, which is of type long long:

__kernel long long lbolt;
printf("%llu", __k:lbolt);


In D, to access the global variable kmem_flags:

printf("%d", `kmem_flags);

Both languages have a native string data type, which can be easily compared with the == operator.

Both DTrace and probevue have built-in variables, but DTrace's are much more complete than VUE's.

Both DTrace and probevue can trace userspace function entry and return. In fact, DTrace can instrument every instruction in userspace. It is unclear what userspace tracing features probevue supports beyond fucntion entry and return.

probevue has syscall and kernel function tracing facility, both of which exposes function arguments.

Unlike DTrace, VUE supported if..else constructions in clause bodies.

There appear to be many similiarities between D and VUE. For example, here is a sample program that records when each thread in an application opens /tmp/foo:

DTrace:
syscall::open:entry
/copyinstr(arg0) == "/tmp/foo"/
{
    self->interested = 1;
}
	
syscall::open:exit
/self->interested/
{
    printf("%d\n", arg0);
    self->interested = 0;
}

The same in probevue:
int open ( char * Path, int OFlag, int mode );

@@syscall:*:open:entry
    when (__arg1 == "/tmp/foo")
{
    thread:interested = 1;
}

@@syscall:*:open:exit
    when (thread:interested)
{
    printf("%d\n", __rv);
}

In a future entry, I'll look at probevue's lists and built-in functions.
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iPhone is so-so as a phone. [Sep. 2nd, 2007|11:33 am]
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My employer bought a few of its employees iPhones to evaluate. I was one of the select few who got one.

As a mobile data device it's pretty good. The mobile web browser is great. The email client is so-so. The lack of supported, native third-party apps is lamentable.

As a phone, it's absolutely terrible.

The voice quality is among the worst I've ever heard. The earpiece is way too quiet (even on max volume). It's especially bad outdoors, where there's ambient noise. I'm constantly jamming the iPhone into my ear to try to hear the other person. It's ringer is so quiet that I can't hear it if I'm in the next room. Two examples stick out in my mind: A few weeks ago, I was driving to New York. The iPhone was sitting on the passenger seat of my car. I had the window down and the radio on, at a regular volume. I missed three incoming SMS messages because the "you have a text message" sound is extremely quiet. Two weeks ago I was walking downtown over my lunchbreak. The iPhone was in my pocket, with the ringer turned all the way up. I missed two calls because I didn't hear the ringer.

The phone also regularly drops calls. For instance, I'm on hold with Apple tech support while I'm writing this (I'm calling about the Macbook issue I whined/blogged about previously). This is the fourth time I've had to call them back because AT&T keeps dropping my call. Before this call, I was talking to my mom; I had to call her back twice due to dropped calls.

My three year-old Verizon Treo 600 was nothing great, but as a phone, it was leaps and bounds ahead of the $600 iPhone.
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