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Managing RAID on Linux
A person deciding to go with RAID faces a panoply of options and gotchas. Hardware or software? How many controllers? ATA or SCSI (or ataraid)? RAID 1 or RAID 5? Which file system or distribution? Kernel options? Mdadm or raidtools? /swap or /boot on raid? Hybrid? Left or right symmetric? One poster pointed out that putting two ATA drives on the same controller could impact performance. Yikes! Didn't I do that? Upon discovering that O'Reilly had just published its Managing RAID on Linux book, looking at sample chapter , I bought the book and let my blood pressure return to normal.
RAID is one of these subjects that is really not complex; it's just very hard to find all the information in one place. This is precisely the book to solve the problem. Author Derek Vadala, sysadmin and founder of Azurance.com, an open source/security consulting firm, has gathered a lot of information and even personal anecdotes to go through the decision making process when going over to RAID. He goes step-by-step through that process, educating us about hard drives, controllers, and bottlenecks along the way. This exhaustive book may be the first to bring RAID to the masses.
Although parts of the book (RAID types, file system types) may seem already familiar to experienced Linux users, it is helpful nonetheless to have everything in a nifty little book. A section of file systems provided not only a rundown of the merits and drawbacks of each one, but also a guide to their utilities. I learned for example what "file tails" for Reiser are, and why using them causes performance to degrade after reaching 85% capacity. The book compares raidtools with mdadm as well as lovely commands like nohup mdadm -monitor -mail=paranoidsysadmin@home.com (which, if you haven't guessed, causes the system to email you RAID status reports upon boot).
People who use software RAID may skip over the chapter on RAID utilities for the leading RAID controller cards. Still, there was one interesting tidbit: Why, the author asks, do makers of controller cards put all their BIOS utilities on DOS floppies which require us to find a DOS boot disk? Seriously, how many of us carry around DOS boot disks nowadays? The book made me aware for the first time of freedos, an open source solution that solves precisely that problem.
The Software RAID stuff was pretty thorough and clarified a lot of things. The book does an excellent job in helping to identify and eliminate bottlenecks and optimizing hard drive performance (using hdparm and various monitoring commands). The anecdotes and case studies definitely clarified which RAID solution is suited for which task.
I am less impressed by the book's sections on disaster recovery and troubleshooting. Although these subjects are brought up at several places in the software RAID chapter, the book could have discussed several failure scenarios or used a fault tree (such as the famous Fault Tree in Chapter 9 of the Samba book, a marvel for any tech writer to read). The book doesn't even discuss booting with software RAID until the last 10 page of the book and then gives it only a single paragraph (even though the author acknowledges it as "one of the most frequently asked questions on the linux-raid mailing list."). Call me old-fashioned, but isn't the ability to boot into your RAID system ... kinda important? As someone who just spent a significant amount of time troubleshooting RAID booting problems in Gentoo, I for one would have liked more insight into the grub/lilo thing. Also, in the next paragraph in the last chapter on page 228, the author casually mentions that "all /boot and / partitions must be on a RAID-1." Say what? Please pity the poor newbie who religiously follows the instructions in the book but fails to read until the end. I'm not sure what the author meant by this statement, but it required a much more substantial explanation and needed to go into a much earlier chapter.
These complaints don't detract very much from this excellent book, a true O'Reilly classic and a model of clarity and helpfulness. This book provides enough knowledge to avoid the dread and uncertainty that comes with trying to tackle Linux RAID. With a book like this, a sysadmin can sleep a little easier.
Recommended Readings:- Reliable Linux , by Iaian Campbell, Wiley and Sons, Dec 2001, ISBN: 0471070408. Gives excellent information not only about RAID but on general Linux reliability issues.
- Software RAID in the Linux 2.4 Kernel by Daniel Robbins. (Part Two).
- Linux Journal Article on Software RAID by Joe Edwards, Audin Malmin and Ron Shaker. ( Part Two).
- "How to do a gentoo install on software RAID" by Chris Atwood. Gentoo User Forum.
Robert Nagle (aka Idiotprogrammer )is a Texas technical writer, trainer and Linux aficionado. You can purchase Managing RAID on Linux from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
but the easiest way I've found is to go with hardware RAID. It's easier to setup, doesn't put any extra load on the CPU, and only costs a few hundred dollars extra.
Mind you I'm thinking of RAID used in producion instead of someone RAIDing two drives in there home machine.
...was the use of the word "panoply".
That word simply isn't used enough in the modern vernacular.
Okay, mod me down now...
"It's a tarp!" -- Dyslexic Admiral Ackbar
Is it possible to use Firewire and a service like Rendevous to make an intelligent redundant system? It's a thought at least. My firewire drive I use for my Inspiron works nicely enough. Would firewire be cheaper than RAID for servers, however?
Syr GameTab.com - Game Reviews Database
panoply
n. pl. panoplies
Looks like number one is most appropriate, although I've never referred to my arrays as "splendid".
The performance hit is not worth the return.
For you, it's not. For someone else, it might be.
There are any number of situations where it might be appropriate to exchange some performance for increased data security. Just because you can't imagine them, doesn't mean they don't exist.
"all /boot and / partitions must be on a RAID-1."
/boot must be RAID1, but / can most assuredly be RAID 5 (or, I presume, any of the other RAID levels). I have this running on an ol' RedHat 7.0 box:
/dev/md1 / ext2 defaults 1 1
/dev/md0 /boot ext2 defaults 1 2
/dev/md0 /dev/sdb1 /dev/sda1
/dev/md1 /dev/sda6 /dev/sdb6 /dev/sdc5
With raidtools, at least,
Hunk 'o fstab:
Similar hunk 'o raidtab
raiddev
raid-level 1
nr-raid-disks 2
chunk-size 64k
persistent-superblock 1
#nr-spare-disks 0
device
raid-disk 0
device
raid-disk 1
raiddev
raid-level 5
nr-raid-disks 3
chunk-size 64k
persistent-superblock 1
#nr-spare-disks 0
device
raid-disk 0
device
raid-disk 1
device
raid-disk 2
*Shrug* Wonder what the context of that quote was within the book?
the no
Does this book talk about the md driver's
multipath personality?
This is the most poorly documented part of the
md driver.
if you read the raidtab man page ("man raidtab")
you will find _no_ mention of multipath whatsovever.
Yet, the md driver can do mulitpath (well, failover) if you set it up right.
It has limitations though... You can't install to multipath devices, or boot from them (lilo/grub, the various distributions installers don't understand md multipath) and, if an hba fails in such a way that interrupts are not generated...commands just go out to lunch... then md won't notice anything is wrong, and so won't failover. Also, it does nothing to notice if the failover path is actually working, so if that path fails you won't have any notice that redundancy is lost....
Well, multipath is not RAID, so maybe this book
doesn't cover it, but any book on software RAID for linux should probably cover all the features of the md driver.
I will be interested to see this book.
I've stepped away from the software RAID idea on my boxes, due to the availability of cheap hardware RAID, such as Promise's SX4000. It will do hardware RAID 5 for four+ drives and has a SDRAM slot for cache expansion. Coupled with LVM, it ended up being a good solution for me, as I had both the reliability, and good volume management if I wanted to combine arrays.
The problem I've had with the software RAID is reliability and expandability. It is a pain in the ass if you lose a drive in the array, and it is next to impossible to add a drive (other than a stand by drive) to your existing RAID 5 setup.
Aah, opinions...
------------------ D. A. Davenport: http://www.firebin.net
Software RAID, excepting mirroring a pair of drives, sucks. Period. The performance hit is not worth the return. Ever do stripping in software? Worse, RAID 5 in software? It sucks. You could spend a few $ and get hardware RAID and not only actually get better performance but not be concerned that some corruption in your OS that is managing that RAID will affect the data stored on it.
It sucks on your hardware. When you use fast SCSI disks and have fast CPU(s), software RAID is much faster then (very expensive) hardware RAID solutions. The chip on your hardware RAID card (usualy ARM) can't be faster than CPU.
Regarding trust, you should trust (open source) software RAID more than proprietary firmware.
Please pity the poor newbie who religiously follows the instructions in the book but fails to read until the end.
On the other hand, pity the newbie who cracks a book open and starts setting a server up page-by-page.
RAID level 01/10 is both expensive *and* pointless
Well, maybe for the average power user, but not the real power users. Pretty much every stock exchange, airline reservations system, credit card switching system in the world uses mirroring and striping. Operating systems such as HP's Non-Stop Kernel (from Tandem) and IBM's Transaction Processing Facility (TPF) work this way and run these mission critical systems.
Why? I/O throughput and redundancy in applications that can't afford to fail. The disks aren't expensive compared to the rest of the system and even less expensive than the downtime.
These aren't Linux systems, but as Linux scales up there will be times when it will necessarily copy from mainframe-class systems.
(From the raid howto)
4.7 The Persistent Superblock
Back in ``The Good Old Days'' (TM), the raidtools would read your /etc/raidtab file, and then initialize the array. However, this would require that the filesystem on which /etc/raidtab resided was mounted. This is unfortunate if you want to boot on a RAID.
Also, the old approach led to complications when mounting filesystems on RAID devices. They could not be put in the /etc/fstab file as usual, but would have to be mounted from the init-scripts.
The persistent superblocks solve these problems. When an array is initialized with the persistent-superblock option in the /etc/raidtab file, a special superblock is written in the beginning of all disks participating in the array. This allows the kernel to read the configuration of RAID devices directly from the disks involved, instead of reading from some configuration file that may not be available at all times.
You should however still maintain a consistent /etc/raidtab file, since you may need this file for later reconstruction of the array.
The persistent superblock is mandatory if you want auto-detection of your RAID devices upon system boot. This is described in the Autodetection section.
Windows software RAID (of any type) sucks, that doesn't necessarily apply to Solaris or Linux (in which I've used both, Solaris tends to be a little bit of overkill in many cases, but if you need it you need it).
/etc files (infact, the IBM EVMS stuff doesn't even use config files, it doesn't need them.. ) Just a few tips for the curious. (I use Gentoo, so I don't have to add these patches.)
As far as IDE channels, many many motherboards these days have about 4 ide channels (mine does, and it's not even NEW) 4 ide channels can make a good raid. My linux RAID 5 (software) is pretty transparent and read speeds are noticable faster. This is even MORE true if you put in the EVMS patches from IBM and use the GUI tools to create and manage RAIDS without even editing
Hardware RAID is marginally, not always better. For one thing, you are limited to the idea of RAID that you board manufacturer believes in.. It's not always what you need. CPU power? On any machine faster than 1ghz you never even notice. 2ghz and software RAID is invisible. Yes, software RAID sucks on windows (due to the stupidest fucking volume/RAID managing service I've ever used), but it's viable almost everywhere else.
Sometimes that extra few hundred dollars is an extra $20k (if you're doing lots of machines), if you can deal with the CPU hit is still more economical as long as it's reliable. Solaris/Linux RAID are ready for prime time, W2k's is still trying to figure it out. (For Windows boxes, please get hardware, save yourself headache.. thanks!)
Jan 26 04:15:02 hostname kernel: hdb: dma_intr: status=0x51 { DriveReady SeekComplete Error }
Jan 26 04:15:02 hostname kernel: hdb: dma_intr: error=0x84 { DriveStatusError BadCRC }
I've looked all over the place for the answer, google, mailing list archives, Usenet, local Linux friends, etc. and haven't been able to find a definitive answer. It's like nobody really knows what that error messages really means.
Newsgroups suggested bad cables, so I replaced those (twice, once with brand new cables bought specifically for the purpose). Some info suggested the drive or the drive's controller was failing, so I replaced it. Other info pointed to my IDE controller, so I installed a new one dedicated only to the RAID pair. I saw info that said the raid tools were to blame, and to see if the errors go away when the mirror is broken. No dice. Other info I found suggested that it was the IDE drivers in the kernel and that the messages were nothing to worry about unless I was seeing data corruption. I'm not seeing corruption so I'm left with this option.
If the book can shed some light on the error message voodoo one sees with Linux's IDE driver, then I'll buy it. I'd pay double what they're asking, even.
-B
Ash and Hickory, straight-grained and true, make excellent bludgeons, dandy for the cudgeling of vegetarians.
While I'm certainly a proponent of "dead-tree" documentation, I have to take a moment to disagree with one of the statements made -- I'm sorry, but newsgroups, while perhaps containing out-of-date info, are (if it's a good newsgroup) capable of letting you know the current state-of-affairs. This is substantially -less- true with books. Case-in-point is Samba: it's *DARN* hard to know, from the Amazon description (or wherever) which Samba books describe the current state (2.4 and above) of Samba, whereas the FAQs, newsgroups, etc., are fairly obvious on it. Bottom line? I'll take a good book any day, but when in doubt, I'll go with current info gleaned off the newsgroups and other on-line resources.
Why, the author asks, do makers of controller cards put all their BIOS utilities on DOS floppies which require us to find a DOS boot disk? Seriously, how many of us carry around DOS boot disks nowadays?
Well, given Dell's recent announcements, I suppose fewer and fewer of us will be doing so.
But really, the author's point is so moot that it's embarassing: if it's my job to maintain a RAID array, and the utilities are on DOS floppies, of course I'm going to have access to a DOS boot disk. So what ? Just how hard is it to carry such a thing around, and why is this is a worthy thing to rail about, in a book about RAID ? If the author wastes too much time talking about stuff like this, this book can't be that useful - arggh, I've wasted too much of my own time already.
That's striping. Why am I even bothering posting this? Maybe if my class wasn't cancelled, you wouldn't have to read such a worthless post.
incripshin
It's not that hard.
- Power down the computer
- Remove cover
- Blow out all dust and insect husks
- Spray in RAID
- put cover back on for 15 minutes.
- Remove cover again
- blow out insect husks.
Trolling is a art,
On a modern machine, software IDE RAID is still beneficial. For striped arrays, the performance penalty on the host CPU is very minimal compared to the device performance. Of course, hardware solutions are easier to set up. If you buy a 3Ware card, or something similar, kernel support is a non-issue. But for home users that just want software to load faster or wish to have backups, IDE RAID is a cheap solution that performs very well.
So, you say it sucks, I say it's fine. You say toe-mott-oh, I say toe-mate-oh. Hardware RAID is more than just a few $. It costs hundred(s) more than software RAID controllers. I've had software controllers that performed better than the current high-end SCSI drives at the time. I can attest to the fact that CPU load was a non-issue. Performance was excellent and was the most inexpensive way to gain speed. It's ideal for home users that aren't wanting to spend a fortune on limiting the swapfile chug.
So, please define "sucks". Enlighten us softRAID users on what the problem is. Or is the problem really that you've spent your fortune on some overpriced SCSI drives that get outperformed by a couple of ATA100s?
RAID 0 is pointless - gosh, I wish all the video editing studios out there knew this. They've been duped into believing 150 megs a second sustained has value. What morons.
Too bad cheap RAID5 cards don't exist. - Hmm, you mean like the Promise SX4000 that costs $150?
I'm Rick James with mod points biatch!
Hmm, I get rather good performance from my IDE software RAID-5. As far as I can tell, reading from the buffers pretty much maxes out the PCI bus and I also get good performance for actual platter reads. Here are some quick numbers:
(granted this is not an exhaustive benchmark)
Not spectacular, but certainly more than fast enough for my media server. Also probably better than I could do on a 68-pin Ultra Wide SCSI bus, even with multiple drives.
Enigma
With disk drives steadily increasing in size, and backup options not keeping pace, everyone has a use for RAID 1. Frankly an extra 100 bucks on another drive is well worth it in comparison to the hassle of maintaining an ongoing backup process. I don't really care that I'm "wasting" a whole drive, since it's still going to be a ton cheaper than any RAID 5 solution.
Ever ripped 500 CDs to MP3 format?
Ever done it twice?
I have, and never will again if I can help it...go RAID 1 go!
That onboard Promise RAID controller you dished out the extra $50 for on that new motherboard is not going to get you a nice hardware RAID 5. AFAIK they can only do 1,0, 0+1, or 1+0. Also, I see people whining about software RAID as compared to hardware RAID. Running a striped set through software was nearly unfeasable a few years ago, but with the resources new machines have these days, the difference is almost negligable, as long as it doesn't have to fight for system resources. let's not forget software RAID is alot cheaper than buying a RAID controller.
At any rate, taking the view that hardware RAID is always the solution and software RAID is never the solution is just bad sysadministration.
Everyone is entitled to their own opinion. It's just that yours is stupid.
Up until now I've bought only SCSI drives because heavy compiles (which I do a lot) just choke IDE down. I now have a 4 x 60 GB RAID-1 and it just screams. With a one time investment in a proper IDE RAID card with escalator scheduling, tagged queueing and big cache I still save a lot of money by being able to buy large but cheap IDE disks.
the poster obviously doesn't know what he's talking about.
a 'rubbish' 500Mhz CPU - 500,000,000 ops / sec
a 5ms access time SCSI HDD - 200 ops / sec.
so what if the CPU on the RAID card is a pathetic 100MHz job, it'll still be able to keep up with the data flow from the HDD, even when that data is being burst through.
How much cache ram have you got on that RAID card is a better indication of performance improvements for your hardware.
I get >160 Megabytes per second off my software striped drives, which is far faster than I've ever gotten off any hardware RAID.
And I've found the RAID 5 overhead is nominal, and very reliable.
No matter how fast your CPU is, you aren't going to beat a dedicated hardware RAID controller. Also, if you're going to spend the money for SCSI, why wouldn't you spend a little more and go with a hardware solution? That's like buying a BMW then "saving money" by adding the fog lights yourself.
You are going to beat hardware controller, because the chip running your software RAID (P4 Xeon, 2GHz) is much faster than the chip on the hardware controller (arm, 100MHz). Your only limitation is the IO bandwidth, thats why you go with SCSI.
Server manufacturers sell hardware RAID as expensive add-on, but they are not advertising any benchmarks showing speed advantage. Because there is none. Current controllers are just not good enough, can't keep up with speed advances of CPUs.
1/ Linux can rebuild RAID from on-disk information. NT 4 is deficient in this regard, it would seem.
2/ Problem is worse with hardware RAID, because if I lose the card, I'm fucked. I either have to have spares, or wait on a controller. Never mind what happens if the manufacturer goes out of business.
When I decided to set up a RAID under Linux, I recalled seeing an icon in my webmin. I used Webmin almost exclusively in setting up the RAID. I didn't need any HOWTOs in the process of setting up this thing.
So while there are good collections of information out there, there are also very good tools out there with which to accomplish useful tasks.
I think it's precisely that HOWTOs are rarely if ever needed with Windows stuff that it still has an edge over Linux where the masses are concerned. So it's nice that HOWTOs are out there, I think it's more important that good tools are out there that are easy and self explanatory.
I think that a better title for this book would be,
RTFM: RAID - The Fucking Manual.
Life is the leading cause of death in America.
EVMS is IBM's version of RAID for linux. This is natively available on gentoo linux. I've been running it on a few boxes with great success. The utilities make it a lot easier to set up raid, lvm, etc.. Definately worth looking at for those interested.
I'm not a real doctor, but I recommend beer.
Sorry, but there are some things to be taken into account here.
:)
First of all, some of today's controllers (such as the HSGs or HP Smart Arrays) are running on pretty good RISC chips. Moreover, they have good amounts of memory to use as read ahead or writeback cache, which do speed up I/O instead of sharing memory with the OS.
About the speed of the controller's processor as compared to the main processor, just remember that, in today's standards, one SCSI channel could only work at 160MB/s, and, even if we needed one processor cycle for each byte to be read/written (we don't), we would only need a 160MHz processor to do the job.
Well, come think about it, processors embedded in today's modern RAID controllers usually have a 64-bit data bus. This means that any transaction is 8 bytes long. Being the worst case in performance a RAID-5 write (which involves 4 I/O operations) we still get an average of 2 bytes per processor cycle.
That's why RAID controllers don't come with fantastic processors -- there's simply no need to.
We could also think of availability, but that would be another long issue, and hardware RAID wins almost in all cases (except for controller multiplexing), but the best reason you would have to think about software raid would be the cost.
I could be wrong, though
As far as IDE channels, many many motherboards these days have about 4 ide channels (mine does, and it's not even NEW) 4 ide channels can make a good raid.
Isn't that just 4 IDE plugs, but only really 2 IDE channels? RAID embedded in your motherboard is usually of the Promise variety and cheap hardware raid isn't much better than software raid. Tom's hardware has an informative article on the difference between hardware and software RAID and they reported that this is the case.
You actually feel good about the Linux drivers that Promise gives you with the SX4000? I bought this card, and I wished I stayed away from it.
I am using it with four 120gb IDE drives with 8mb cache. For starters, if you use anything but the sxcslapp program in Linux to configure the drive, your drives are corrupt. All of 'em. And, your bios will return corrupt information regarding them. This causes DOS not to boot (hard freeze), and Linux to produce keyboard smashings on boot. This is a known firmware problem, and I'll be damned if they have any flashes available, even though the card is four months old. I just checked before writing this review.
Once I figured out that all the work had to be done with sxcslapp in Linux, I started building my RAID5, albeit with caution. Things here went pretty well, except a) performance sucked about as bad as a single drive and b) the closed source drivers rebuild the raid array with no warning if a drive fails and is replaced, even if the file system is mounted. So, this means that if you have a drive that bombs and you replace it, anything you write to the raid array will be wiped out. I could have used some notification.
The Linux drivers are horrible. They are written in 'Engrish', and the documentation might as well have been written by someone who doesn't understand computers. "Select the remove drive from array option to remove a drive from array". This continues for all of the options in their menu-driven app.
I am also forced to use Red Hat 7.3 for this. Great. I now have a cluster of Debian 3 servers I administrate and one Red Hat server.
I would have returned the card if my reseller would have taken my money. It's about equally expensive to buy IDE add-on cards, or maybe a bit less, and the software RAID in Linux seems to be firmly documented. I've used RAID1 in software on servers before, and it works nicely.
3-4 years ago, when we decided to use hardware RAID on our Linux servers, we bought some DPT Smartraid V hardware RAID controllers. Unfortunatly DPT was bought by Adaptec some time after. Adaptec has been really good at getting the driver included in the kernel, but the takeover seemed to delay this proces, so the time in between was a rough ride.
The lesson learned was, never have a production Linux system with (binary) drivers tied to a specific kernel or distro version.
That said, we have been very happy with the controllers, and since at least two disks has died without warning, the expense has easely been worth it. Our systems are used 24/7/365, so every minute of downtime annoys somebody. RAID really makes me sleep better, restoring a server from a slow tapestreamer, at some ungodly hour, while people nervously checks in, asking when we will be up again, is something I really want to avoid too much of.
YMMV, but I think hardware RAID still has an edge over software raid, mostly because I find it simpler to maintain in the long run.
If you are into LVM's, FS tools, and software RAID, go to:
http://evms.sourceforge.net/
and _drool_. Future stuff for now on production servers, but nevertheless.
at O'Reilly, mdadm
and, I'd recommend Enterprise Volume Management System rather than LVM ( Logical Volume Manager ), simply because LVM's seems to be being dropped as
redundant ( ironic, that : ) as EVMS gets more effective, and I don't want the conversion-work from LVM to EVMS, if I can just do EVMS right now, see
Messages to/for me ( in me journal )
but the controller's CPU doesn't need to be that fast, most of the logic is in ASICs anyway. the key advantage to having a controller is that it handles all the drive processing and this reduces the amount of work your main CPU has to do. remember: accessing the drive is not all your machine is doing. also most high-end controllers have large memory caches that reduce the load on your system bus, and battery backup that is essential for data integrity during power-loss. for example, in a mirrored RAID situation a software implementation will have to do 2 DMAs per write, one to each drive. with a hardware controller you only need one DMA to the card, the card handles writing to the individual drives, and will often reorganize the order of the writes from its cache.
I've just been through setting up a raid system. I set up a file server that automatically backs up data every week that the users on the network put on it via samba. Since I only want to show up at the place every 6 month or so to check on the server it needs to be bullet proof to the max and still cheap, because they don't have much money as social workers.
:-(, since doku is the last thing those guys seem to think about.
I purchased a used p2 system with a stable mb and two ibm scsi drives on an adaptec controller. I installed Debian GNU/Linux stable and upgraded to the latest stable. Then I put up a softraid and opted for xfs in case of a power failure. I decided against an ups, because I hooked the machine up to the local power network, which is very stable, since the server lives in Berlin/Germany, and I wanted to save the cost.
Then I moved the root filesystem over to the raid device. Up until now everything was documented very good, except for the fact, that I heard that reiserfs doesn't work with softraid and I didn't find that info on the net anymore. I would have taken reiserfs instead if I would have had a reliable source, such as the book, telling me that that is OK.
The only thing I had problems with was how to make the system boot off the raid device. Here the howtos and man pages had contradicting stands on how to do this.
I read this Slashdot article with some regret, because I thought it could have saved me a lot of trouble. But the only section that gave me trouble also seems to confuse the auther of the book. Now that is no help at all. So this book is a waste of time if You know how to use google, which I had to learn painfully fast getting into Debian
But since Debian is still by far the best system out there overall I have no choice. If You start to rely on seemingly simple things such as a reliable update of Your system with very low hassle then You are hooked.