Gentoo Archives: gentoo-desktop

From: Lindsay Haisley <fmouse-gentoo@×××.com>
To: gentoo-desktop@l.g.o
Subject: Re: [gentoo-desktop] Re: System problems - some progress
Date: Sat, 26 Mar 2011 02:48:09
Message-Id: 1301107592.1735.102.camel@ubuntu
In Reply to: [gentoo-desktop] Re: System problems - some progress by Duncan <1i5t5.duncan@cox.net>
1 On Fri, 2011-03-25 at 22:59 +0000, Duncan wrote:
2 > Simply my experience-educated opinion. YMMV, as they say. And of course,
3 > it applies to new installations more than your current situation, but as
4 > you mentioned that you are planning such a new installation...
5
6 Duncan, thanks for your very thorough discussion of current technologies
7 disk/RAID/filesystem/etc. technologies. Wow! I'm going to have to read
8 it through several times to absorb it. I've gotten to the point at
9 which I'm more involved with what I can _do_ with the Linux boxes I set
10 up than what I can do that's cool and cutting edge with Linux in setting
11 them up, but playing with bleeding-edge stuff has always been tempting.
12 Some of the stuff you've mentioned, such as btrfs, are totally new to me
13 since I haven't kept up with the state of the art. Some years ago we
14 had EVMS, which was developed by IBM here in Austin. I was a member of
15 the Capital Area Central Texas UNIX Society (CACTUS) and we had the EVMS
16 developers come and talk about it. EVMS was great. It was a layered
17 technology with an API for a management client, so you could have a CLI,
18 a GUI, a web-based management client, whatever, and a all of them useing
19 the same API to the disk management layer. It was an umbrella
20 technology which covered several levels of Linux MD Raid plus LVM. You
21 could put fundamental storage elements together like tinker-toys and
22 slice and dice them any way you wanted to.
23
24 EVMS was started from an initrd, which set up the EVMS platform and then
25 did a pivot_root to the EVMS-supported result. I have our SOHO
26 firewall/gateway and file server set up with it. The root fs is on a
27 Linux MD RAID-1 array, and what's on top of that I've rather forgotten
28 but the result is a drive and partition layout that makes sense for the
29 purpose of the box. I set this up as a kind of proof-of-concept
30 exercise because I was taken with EVMS and figured it would be useful,
31 which it was. The down side of this was that some time after that, IBM
32 dropped support for the EVMS project and pulled their developers off of
33 it. I was impressed with the fact that IBM was actually paying people
34 to develop open source stuff, but when they pulled the plug on it, EVMS
35 became an orphaned project. The firewall/gateway box runs Gentoo, so I
36 proceeded with regular updates until one day the box stopped booting.
37 The libraries, notably glibc, embedded in the initrd system got out of
38 sync, version wise, with the rest of the system, and I was getting some
39 severely strange errors early in the boot process followed by a kernel
40 panic. It took a bit of work to even _see_ the errors, since they were
41 emitted in the boot process earlier than CLI scroll-back comes into
42 play, and then there was further research to determine what I needed to
43 do to fix the problem. I ended up having to mount and then manually
44 repair the initrd internal filesystem, manually reconstituting library
45 symlinks as required.
46
47 I've built some Linux boxes for one of my clients - 1U servers and the
48 like. These folks are pretty straight-forward in their requirements,
49 mainly asking that the boxes just work. The really creative work goes
50 into the medical research PHP application that lives on the boxes, and
51 I've learned beaucoup stuff about OOP in PHP, AJAX, etc. from the main
52 programming fellow on the project. We've standardized on Ubuntu server
53 edition on SuperMicro 4 drive 1U boxes. These boxes generally come with
54 RAID supported by a proprietary chipset or two, which never works quite
55 right with Linux, so the first job I always do with these is to rip out
56 the SATA cabling from the back plane and replace the on-board RAID with
57 an LSI 3ware card. These cards don't mess around - they JUST WORK.
58 LSI/3ware has been very good about supporting Linux for their products.
59 We generally set these up as RAID-5 boxes. There's a web-based
60 monitoring daemon for Linux that comes with the card, and it just works,
61 too, although it takes a bit of dickering. The RAID has no component in
62 user-space (except for the monitor daemon) and shows up as a single SCSI
63 drive, which can be partitioned and formatted just as if it were a
64 single drive. The 3ware cards are nice! If you're using a redundant
65 array such as RAID-1 or RAID-5, you can designate a drive as a hot-spare
66 and if one of the drives in an array fails, the card will fail over to
67 the hot-spare, rebuild the array, and the monitor daemon will send you
68 an email telling you that it happened. Slick!
69
70 The LSI 3ware cards aren't cheap, but they're not unreasonable either,
71 and I've never had one fail. I'm thinking that the my drive setup on my
72 new desktop box will probably use RAID-1 supported by a 3ware card.
73 I'll probably use an ext3 filesystem on the partitions. I know ext4 is
74 under development, but I'm not sure if it would offer me any advantages.
75 I used reiserfs on some of the partitions on my servers, and on some
76 partitions on my desktop box too. Big mistake! There was a bug in
77 reiserfs support the current kernel when I built the first server and
78 the kernel crapped all over the hard drive one night and the box
79 crashed! I was able to fix it and salvage customer data, but it was
80 pretty scary. Hans Reiser is in prison for life for murder, and there's
81 like one person on the Linux kernel development group who maintains
82 reiserfs. Ext3/4, on the other hand, is solid, maybe not quite as fast,
83 but supported by a dedicated group of developers.
84
85 So I'm thinking that this new box will have a couple of
86 professional-grade (the 5-year warranty type) 1.5 or 2 TB drives and a
87 3ware card. I still haven't settled on the mainboard, which will have
88 to support the 3ware card, a couple of sound cards and a legacy Adaptec
89 SCSI card for our ancient but extremely well-built HP scanner. The
90 chipset will have to be well supported in Linux. I'll probably build
91 the box myself once I decide on the hardware.
92
93 I'm gonna apply the KISS principle to the OS design for this, and stay
94 away from bleeding edge software technologies, although, especially
95 after reading your essay, it's very tempting to try some of this stuff
96 out to see what the the _really_ smart people are coming up with! I'm
97 getting off of the Linux state-of-the art train for a while and go
98 walking in the woods. The kernel will have to be low-latency since I
99 may use the box for recording work with Jack and Ardour2, and almost
100 certainly for audio editing, and maybe video editing at some point.
101 That's where my energy is going to go for this one.
102
103 --
104 Lindsay Haisley |"Windows .....
105 FMP Computer Services | life's too short!"
106 512-259-1190 |
107 http://www.fmp.com | - Brad Johnston

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Subject Author
[gentoo-desktop] Re: System problems - some progress Duncan <1i5t5.duncan@×××.net>