[TUHS] Why Linux not another PC/UNIX [was Mach for i386 ...]

[Arthur Krewat]

The line of succession for me, starting with my hobby/business UNIX 
installs on Intel was:

Beginning 1991-1992, Consensys SVR4 - Used up until around 1995. UUCP 
and USENET. Ran a BBS off of this and was a USENET node "kilowatt" 
during that time. I'm in NIXPUB. Buying this version of UNIX was for a 
joint business venture I went into with a friend, and we needed a decent 
UNIX platform to work with without a huge hardware cost. Very happy with 
it, but it did have some bugs. Wound up getting a few UNIXware drivers 
with fixes that took care of many of the issues mostly to do with the 
Adaptec 1541 SCSI card.

I toyed with Linux around this time, but there was a local BBS guy who 
was such a fanboy that I was turned off by it - and there was NO 
advantage to it over SVR4 at that time. All I saw was a bunch of stuff 
glued together that was not "real" UNIX. It also offered almost no 
possibility of developing for SunOS or the up and coming Solaris 2.x

During the above time, I also ran a Sparc-IPC with SunOS 4.1.2(3?) on it 
so it wasn't for lack of having a decent hardware platform to work with. 
I did a lot of SunOS development on it, and wrote stuff that I could 
compile it on both SVR4 and SunOS

Around 1994-1995, started getting into FreeBSD - which I loved. Ran that 
from 1995 or so right up until around 1999 as my main firewall/router on 
one machine, and file server on another. Device support was better than 
Consensys, and I could fix any bugs I found myself if I had to - but 
never really had to. And, it was much like SunOS 4, if you squinted and 
tilted your head slightly.

Also around that timeframe, I think I toyed with Solaris 2.4 or 2.5 on 
x86, but I know I that I went fully into Solaris x86 around the 
late-1998/early-1999 with Solaris 2.7

I'm not entirely sure when it was but at various times I checked out 
Linux on test machines. I had instances where I thought "oh boy! this is 
cool" but then, my installed base of computers and development 
environments meant having to go whole-hog into Linux for at least one of 
my machines and I had too much invested in them in terms of time.

At one point, I decided I needed to find an alternative to my main 
workstation (running on Solaris 7 or maybe even 8 by this time) and 
turned back to Linux for it's plethora of device drivers and third-party 
applications - mostly audio/video players, Adobe Flash, Acrobat Reader, 
that sort of thing.

This was the time of the turning-point for me for Linux, and it was 
turning AWAY from it for a long time. Still haven't recovered from it.

I found that while running a decent-sized machine at the time - maybe it 
was 64 megs of RAM, maybe it was even more, I really don't remember. I'd 
have to go back and look at my old archived hardware to find out.

Suffice it to say, I had a machine that made a GREAT Windows NT 4.0 
machine. Did everything I wanted, plenty of applications ran on it, etc. 
So, I started to look at Linux again, because I detested Windows at the 
time. Installed it, early kernel 2.6 version, it ran great, did 
everything. Netscape, Flash, Acrobat Reader, some word processing (don't 
remember what), etc.

Problem was, after running a while, it got really REALLY slow and kept 
banging the disk for long periods of time. Took about 5 seconds to 
realize what it was. It had swapped out most of the application pages to 
disk. Click on a link in Netscape, chunka-chunka-chunka. Go to a shell 
and try to do an ls, chunka-chunka-chunka.

Found some references for kernel 2.4 that you could limit the amount of 
disk cache. So went to try that, 2.6 didn't have that anymore. So I went 
online, forget where, maybe it was a mailing list, maybe it was a USENET 
group, I really don't remember.

I remember asking why the HELL did they remove that when it so obviously 
caused the system to get slower than dog-shit in a snow storm. First, it 
was "you need more RAM" - yeah, I never like the "go buy more hardware 
answer" neither for myself nor my customers. Strike one. Continue the 
discussion, and got some answer like "We know better than you do about 
how to deal with virtual memory, go away". This, after having worked 
with SunOS, Solaris, HP/UX, IBM AIX, SCO, SGI, and everything else under 
the sun that did NOT DO THIS. The discussion continued like that a 
little bit, and I turned around, installed Windows NT on the machine, 
and never looked back until the past 5-6 years where I've been forced to 
deal with Linux.

Of course, now, there are tunables to alter the "pressure points" and 
timing of how the kernel decides that it needs a page for disk cache 
more than the application does.

By default Oracle Linux will still swap the Oracle database itself out 
to disk when it thinks it needs more disk cache. That blows. Answer is 
to open the Oracle on Linux best practices PDF and set all the tunables 
to different values, and VOILA - now it only swaps out once in a while. 
Of course one of those is "swappiness" which for years seemed to do 
absolutely nothing.

So now, it's OK - when a company I consult for eventually brings up "We 
can run this on Linux, right? We need to cut costs" - My answer is "yes" 
even though I don't want to. But when you consider a SPARC or IBM AIX 
box compared to an Intel Linux box, it's really a no-brainer. My only 
caveat when they do this is: If you had X amount of RAM in your existing 
system, and you're not making any substantial changes, double it for the 
Linux box. This tends to relieve the pressure to swap out, but it still 
doesn't completely remove it. And then, of course, I send them a 
document with all the tunables I've gathered.

Anyway, long winded, rambling story, but I think you all might get the 
idea why for ME it wasn't the answer.

After that period of time, I upgraded some of my hardware to newer 
dual-core AMD, and started running Solaris 10 and used ZFS for the first 
time in my "production" environment. What a blast ZFS has been. Linux 
doesn't come out-of-the-box with ZFS support? Oh well... see ya! :)

I now have over 56TB of multiple raidz2 arrays spread over 46 disks or 
so all tied to a Solaris 11.3 machine and run multiple Solaris guests in 
VMware. Still not going Linux except when I need to test/develop stuff 
for customers and that's always on a VMware guest.

zfs_arc_max for-the-win. And now, for Solaris 11.3|, 
|user_reserve_hint_pct - even better.

Yes, I grew up to be a "real UNIX" snob. Now, at 51 years old, I'm 
confident I made the right choice. I know enough about Linux to make 
sure my customers are well taken care of. But for my personal use, if I 
have to, I'll go back to FreeBSD and ZFS before I run Linux. Hopefully 
Oracle does the "right thing" with Solaris when it's time.



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