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dusanc
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 Posted: Mon Sep 01, 2008 6:25 pm Post subject: Reiser4 Gentoo FAQ [17Jan2013] |
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As I've noticed that some Reiser4 questions get asked all the time I think that this thread will be useful so that people should have one central place for answers.
All the Q and A will be in this first post.
_______________________________________________________________________
Q1: How to start using Reiser4?
You need:
1. kernel (>= 2.6.36) patched with latest patches from http://sourceforge.net/projects/reiser4/files/reiser4-for-linux-3.x/
2. reiser4.progs-1.0.7 or higher http://sourceforge.net/projects/reiser4/files/reiser4-utils/
3. create reiser4 partition with:
Plain Reiser4: | Code: | | mkfs.reiser4 /dev/xxx |
Reiser4+cryptocompression: | Code: | | mkfs.reiser4 -o create=ccreg40 /dev/xxx |
4. mount the new partition with -noatime option in fstab
Q2: Why does du reports wrong size of data?
"du (1) statistics does not reflect (online) real space usage, as
i_bytes and i_blocks are unsupported by cryptcompress plugin
(supporting those fields "on-line" leads to performance drop).
However, their proper values can be set "offline" by reiser4.fsck." -Edward Shiskin
http://marc.info/?l=reiserfs-devel&m=117400217826615&w=2
Q3: I get lots of errors about wrong size when fscking cryptocompress R4 partition. Am I in trouble?
No you're not. These are false positives when checking cryptocompress data. That's proper values mentioned in Q2. As of version of reiser4.progs-1.0.7 these issues are fixed. These warnings can be suppressed with -s.
Q4: I'm having trouble with OpenRC and Reiser4, how can I fix it?
Set fsck_args="-a" in /etc/conf.d/fsck
Shouldn't be a problem with recent OpenRC
Q5: Can I use loopback files on reiser4?
You can on plain Reiser4. On Reiser4+cryptocompress you have to create loopback file this way:
| Code: | | dd if=incompressible_file of=loopfile bs=65537 count=1 |
Now using some incompressible file we created new file (of has to be new file) that R4 will remember as incompressible.
http://marc.info/?l=reiserfs-devel&m=121262617103900&w=2
This item should be fixed in recent kernels.
Q6: What are the R4 strongpoints?
Usage with small files, low fragmentation especialy with cryptocompression, efficient space usage (usual / without /home is 40% smaller with R4+cc than with plain ext3), robustnes wrt. power failures, very fast for certain workloads (eg. for /usr/portage).
Q7: What are R4 weak points?
Currently some large multimedia files are falsely considered as compressable.
Loopback support still has some rough edges
Performance with atime can be low on cryptocompressed partitions, and deletion of large files on cryptocompressed partitions can take more time than on plain partitions. This is a trade off for better overall performance.
Q8: Where can I find some benchmarks?
http://marc.info/?l=reiserfs-devel&m=121484256609180&w=2
http://openbenchmarking.org/result/1104010-JPEI-110329637
Q9: How would I know what's the right fs for me?
Every fs has its strongpoints, so try to use those which suits you most. Test them not with some synthetic benchmarks, but with your usage patterns. Comparative tests have to be under same conditions (same partition etc.). If you want to know what fs is best against power failures format a USB flash with it and yank it out during copying lots of small files and during copying one large file. When you remount it fsck and make conclusions.
Q10: I've formated my / with r4 and now can't boot. What should I do?
You'll have to use a separate /boot partition (50-100MB ext2).
Q11: When will Reiser4 be included in mainline Linux kernel?
Ask $DEITY.
| Quote: | I don't see any technical obstacles for Reiser4 inclusion. There are only organisation ones: I don't think it will be accepted without support from some vendor.
Thanks,
Edward. |
http://www.phoronix.com/scan.php?page=news_item&px=OTA2Mw
Q12: Where can I find more informations?
There's a mailing list reiserfs-devel@vger.kernel.org with archives and IRC channel #reiser4 at irc.oftc.net
There's a wiki too at http://reiser4.wiki.kernel.org/index.php/Main_Page
Q13: Where can I find a LiveCD with Reiser4 support?
www.sysresccd.org supports Reiser4 from version 3.1.1: http://sourceforge.net/projects/systemrescuecd/files/sysresccd-x86/
Q14: Any bugs that I should know of?
All of these bugs are reported as fixed as of reiser4-for-3.7 http://marc.info/?l=reiserfs-devel&m=135844802421045&w=2
Q15: Are there any tuning options?
There is a dedicated Reiser4 tuning thread at http://forums.gentoo.org/viewtopic-t-707465.html
Q16: Why is there no patch for just released linux kernel?
VFS layer in linux kernel changes from time to time, and fixing the R4/VFS interraction is usually a nontrivial task bacause bugs can be easily introduced and because we like our data. All we can do is wait.
Q17: Does it support encryption?
| Edward wrote: | Actually it is implemented on a low level. Moreover,
long time ago I got a reiser4 partition transparently
compressed and ciphered by aes ecb. The problem
was that Linux didn't have a good key manager. Now
I believe that the situation is improved, so in order to
announce encryption we need:
1. a fast iv-generator stable to watermark attack for
cbc encryption mode;
2. to adjust any convenient key manager to perform
encryption per file/directory/volume.
I estimate the complexity of this task as 2 of 5.
Thanks,
Edward.
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http://marc.info/?l=reiserfs-devel&m=125983401120315&w=2
Q18: Are there any special options when using Reiser4 on a SSD? What about TRIM support?
There are none.
| Quote: | If you align your FS, use -noatime as you should do with any FS on SSD, thing is that good SSD controllers won't detoriate easily over time (like Intel or sandforce ones). Not using your SSD for portage, tmp, or swap helps too 
And as R4 does a great job of packing small writes, and has low fragmetation, detoriation is slower still.
You can clear your SSD after few years when you reinstall, or you can use recent hdparm and wiper tool ( http://sourceforge.net/projects/hdparm/files/ ) to discard trash on unmounted partition. BUT BE CAREFUL! Only safe data is with paranoid backups done with tinfoil hat
TRIM discards sectors supplied to it that don't contain data, but if wrong sectors are supplied to it, it'll discard them and eat your data.
And I don't use it, so proceed with caution, or ask someone who has.
But if you really need automatic online trash collection and automatic online trim by FS alone, reiser4 doesn't do it 
It relies on user space for it
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http://forums.gentoo.org/viewtopic-p-6533722.html#6533722
_____________________________________________________________________
I hope that this will help people and I would be very grateful for every addition/correction to this FAQ.
Have fun
Dushan
Edit:
17Jan2013: Updated Q1 and Q14 as there are no more open bug reports.
08Dec2012: Q13: R4 support is back in SystemRescueCD. Q14: Added some current bug info.
10Sep2012: Updated links in Q1 and Q13, and updated Q14
15Nov2011: Updated to new location of files since kernel.org was compromised. Updated Q14.
11Jun2011: Updated Q11.
30May2011: Added new bug info to Q14.
04Apr2011: Added more benchmarks and updated Q10 (there's no grub support for R4).
08Feb2011: Updated Q14.
04Jan2011: Added more info to Q18.
30Dec2010: Updated Q1, Q7, Q14, added Q18.
13Jan2010: Added Q17, bugs info to Q14, wiki link to Q12, and inclusion info to Q11.
11Jan2010: Added Q16.
25Jul2009: Added info about hitchhiker sources.
07Apr2009: Added info about GCC build bug, and about tuning thread.
27Feb2009: Added info about reiser4.progs-1.0.7, and brought some issues up to date.
08Sep2008: Added minimum kernel version to use and location of R4 LiveCD, thanks to gentree and neuron.
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Reiser4 Gentoo FAQ [17Jan2013]
Last edited by dusanc on Thu Jan 17, 2013 10:33 pm; edited 36 times in total |
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Mr. Tao
Tux's lil' helper
Joined: 20 Jul 2007
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| Posted: Mon Sep 01, 2008 7:31 pm Post subject: |
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Nice summary. I just would like to add that after experimenting with loop files on R4 a lot (different kernels and machines) I wouldn't recommend this for serious use (like portage or ccache). It always led to problems, sometimes fatal, at least for me. Typical symptoms are long syncs (in order of tenths of minutes) ocassionaly ending with on-loop fs corruption as fatal that it couldn't be recovered by fsck. Since I gave up and use separate partitions for used-to-be-in-loop-file content I'm very satisfied with Reiser4  |
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DigitalCorpus
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| Posted: Tue Sep 02, 2008 7:40 pm Post subject: |
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Since there are two types of compression, do you want to include how to enabled one over the other and a simple speed/performance trade off? SPeaking of which, has anyone identified how much more compression one would get on average and how much of a performance impact there is?
| Code: | | create=ccreg40,compress=gzip1 |
and | Code: | | create=ccreg40,compress=lzo1 |
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Gentree
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| Posted: Sun Sep 07, 2008 11:38 pm Post subject: |
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| Quote: | | It always led to problems, sometimes fatal, at least for me. |
Oh, I'm sorry to hear that. I hope your death was quick and painless. 
Personally, I've found R4 rock solid despite all too frequent power outs here, (though I don't use compression, the rare times I've used loopback has been fine).
Nice overview. You could add which kernel version is needed for compression plugin.
regards.
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KX7-333 , AthlonXP1800+ @2.3GHz
AthlonXP-M on A7N8X @ 2.6/2.4GHz (winter/summer)
2.6.32-hh1 : portage ~x86 |
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neunon
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| Posted: Mon Sep 08, 2008 12:20 am Post subject: |
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| Might be good to add that SystemRescueCD can be used if you want to set up a Gentoo install with the root FS being Reiser4. |
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MostAwesomeDude
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Joined: 12 Aug 2007
Posts: 373
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| Posted: Tue Sep 09, 2008 7:08 am Post subject: |
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| Gentree wrote: | | Quote: | | It always led to problems, sometimes fatal, at least for me. |
Oh, I'm sorry to hear that. I hope your death was quick and painless. |
Well, one for two, I guess.
| Quote: | | Personally, I've found R4 rock solid despite all too frequent power outs here, (though I don't use compression, the rare times I've used loopback has been fine). |
The reports are solid, although I've found it to be a bit verbose while debugging.
| Quote: | | Nice overview. You could add which kernel version is needed for compression plugin. |
Personally, I prefer compression by pieces.
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minor_prophets
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| Posted: Fri Jan 16, 2009 1:52 am Post subject: |
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| Feel like sharing some /etc/fstab examples? R4, of course. |
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Dont Panic
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Posts: 317
Location: SouthEast U.S.A.
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| Posted: Fri Jan 16, 2009 3:00 pm Post subject: |
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This is a simple example I have for my Reiser4 root partition
| Code: | | /dev/sdb6 / reiser4 noatime,nodiratime 1 1 |
With the latest versions of Mozilla Firefox, I've found that 'noatime' is fairly important.
There's another Reiser4 tuning thread going on here that has more examples:
http://forums.gentoo.org/viewtopic-t-707465.html |
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minor_prophets
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| Posted: Fri Jan 16, 2009 7:59 pm Post subject: |
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Simple as that, huh.
I saw an interesting fstab on root part. over on the "Filesystems Choice thread" by KernelofTruth(?) I think. I'll post it when I reach my place of peace... |
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minor_prophets
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| Posted: Sat Jan 17, 2009 1:07 am Post subject: |
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taking a look at that thread in a minute.
I remember the opts not.
noatime,nodiratime,flush,scan_maxnodes=15000
I'm just trying to find a link to reiser4 mount options and also reiser4 patches for grub  |
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Dont Panic
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| Posted: Sat Jan 17, 2009 1:34 am Post subject: |
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| With respect to grub, I took the easy way out, and copy my boot files to a regular reiserfs partition, and boot from that partition initially. |
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minor_prophets
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| Posted: Sat Jan 17, 2009 1:39 am Post subject: |
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I was just about to post a "nevermind" regarding the reiser4 grub patch as I realized I probably don't need it.
/boot is ext2 and I have the kernel sources patched and reiser4 support activated there.
This is correct, no? |
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neuron
Advocate
Joined: 28 May 2002
Posts: 2371
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| Posted: Sat Jan 17, 2009 12:09 pm Post subject: |
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| minor_prophets wrote: | I was just about to post a "nevermind" regarding the reiser4 grub patch as I realized I probably don't need it.
/boot is ext2 and I have the kernel sources patched and reiser4 support activated there.
This is correct, no? |
Correct |
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Hell-Razor
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| Posted: Sat Jan 17, 2009 12:47 pm Post subject: |
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Hey guys I finally found some people that seem to like reiser4
Anyway I have reiser4 on my /home partition (and love it) and reiserfs on my / partition. Anyway the problem is ever sense I installed reiser4 it seems during boot localmount takes FOREVER to mount everything. It takes about three-five minutes and I just keep on getting an error saying "waiting on local mount" and it just repeats until it is finally done. Any ideas of what I can do to see what is wrong / speed it up?
Thanks in advanced.
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kernelOfTruth
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Dont Panic
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| Posted: Sat Jan 17, 2009 4:50 pm Post subject: |
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It's good to see some activity and releases in reiserfs and reiser4.
I know a few people who like reiser4, but they're just expecting it to disappear as a project someday.
Some signs of active development, even if it is just mostly bug patches, will hopefully change the perception that it's a near-dead project. |
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dusanc
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| Posted: Sat Jan 17, 2009 8:13 pm Post subject: |
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| Hell-Razor wrote: | Hey guys I finally found some people that seem to like reiser4
Anyway I have reiser4 on my /home partition (and love it) and reiserfs on my / partition. Anyway the problem is ever sense I installed reiser4 it seems during boot localmount takes FOREVER to mount everything. It takes about three-five minutes and I just keep on getting an error saying "waiting on local mount" and it just repeats until it is finally done. Any ideas of what I can do to see what is wrong / speed it up?
Thanks in advanced. |
Well 3 things.
fsck your partitions
noatime in fstab
If you /home is pretty large (for me 200GB takes 13sec) you could add dont_load_bitmap (I hope it's correct, look in docs) in kernel parameters, so that r4 doesn't load pretty large bitmap to ram on boot time, but on load.
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Reiser4 Gentoo FAQ [17Jan2013] |
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minor_prophets
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| Posted: Mon Jan 19, 2009 3:17 am Post subject: |
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Good tips.
I'm using one from kernelofTruth. scan_maxnodes=15000.
My question is rather noobish, though, as I'm questioning its appropriateness for all reiser4 partitions or just the root part. |
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Hell-Razor
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| Posted: Mon Jan 19, 2009 3:45 am Post subject: |
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| dusanc wrote: | | If you /home is pretty large (for me 200GB takes 13sec) you could add dont_load_bitmap (I hope it's correct, look in docs) in kernel parameters, so that r4 doesn't load pretty large bitmap to ram on boot time, but on load. |
My /home dir is huge, im assuming ~700 gigs.
I will check the bitmap thing out when I get home. What is it used for and why would it want to be loaded? and are there any risks with not loading it?
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HecHacker1
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| Posted: Mon Jan 19, 2009 4:37 am Post subject: |
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For reference, from:
http://lists.pld-linux.org/mailman/pipermail/pld-cvs-commit/Week-of-Mon-20070806/163501.html
Probably not the newest.
| Code: | ++Mount options
++=============
++tmgr.atom_max_size=N
++ Atoms containing more than N blocks will be forced to commit.
++ N is decimal.
++ Default is nr_free_pagecache_pages() / 2 at mount time.
++
++tmgr.atom_max_age=N
++ Atoms older than N seconds will be forced to commit. N is decimal.
++ Default is 600.
++
++tmgr.atom_max_flushers=N
++ Limit of concurrent flushers for one atom. 0 means no limit.
++ Default is 0.
++
++tree.cbk_cache.nr_slots=N
++ Number of slots in the cbk cache.
++
++flush.relocate_threshold=N
++ If flush finds more than N adjacent dirty leaf-level blocks it
++ will force them to be relocated.
++ Default is 64.
++
++flush.relocate_distance=N
++ If flush finds can find a block allocation closer than at most
++ N from the preceder it will relocate to that position.
++ Default is 64.
++
++flush.scan_maxnodes=N
++ The maximum number of nodes to scan left on a level during
++ flush.
++ Default is 10000.
++
++optimal_io_size=N
++ Preferred IO size. This value is used to set st_blksize of
++ struct stat.
++ Default is 65536.
++
++bsdgroups
++ Turn on BSD-style gid assignment.
++
++32bittimes
++ By default file in reiser4 have 64 bit timestamps. Files
++ created when filesystem is mounted with 32bittimes mount
++ option will get 32 bit timestamps.
++
++mtflush
++ Turn off concurrent flushing.
++
++nopseudo
++ Disable pseudo files support. See
++ http://namesys.com/v4/pseudo.html for more about pseudo files.
++
++dont_load_bitmap
++ Don't load all bitmap blocks at mount time, it is useful for
++ machines with tiny RAM and large disks. |
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Hell-Razor
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| Posted: Mon Jan 19, 2009 6:35 am Post subject: |
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Sweet thanks HecHacker1. Where do I add this line? just in my grub.conf kernel line ? I would assume so so here is a clip of what I added --
| Code: | title Gentoo Linux 2.6.27-r2
root (hd0,0)
kernel /boot/gentoo-sources-2.6.27-r2 root=/dev/sda3 vga=0x317 dont_load_bitmap |
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kernelOfTruth
Watchman
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Posts: 5490
Location: Vienna, Austria; Germany; hello world :)
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| Posted: Mon Jan 19, 2009 9:16 am Post subject: |
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| Hell-Razor wrote: | Sweet thanks HecHacker1. Where do I add this line? just in my grub.conf kernel line ? I would assume so so here is a clip of what I added --
| Code: | title Gentoo Linux 2.6.27-r2
root (hd0,0)
kernel /boot/gentoo-sources-2.6.27-r2 root=/dev/sda3 vga=0x317 dont_load_bitmap |
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those are MOUNT options, so just add them to /etc/fstab
there you might have "defaults", or "noatime,nodiratime" add that thingy there
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dusanc
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| Posted: Mon Jan 19, 2009 10:06 am Post subject: |
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Nope, thing like don't load bitmap have to go to kernel options, Edward told me
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Reiser4 Gentoo FAQ [17Jan2013] |
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kernelOfTruth
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Hell-Razor
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Posts: 427
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| Posted: Mon Jan 19, 2009 12:03 pm Post subject: |
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Alright lets see here, my fstab -
| Code: | /dev/sda1 /boot reiserfs noauto,noatime,notail 0 2
/dev/sda3 / reiserfs noatime,notail 0 1
/dev/sda2 none swap sw 0 0
/dev/sdb1 /home/ reiser4 noatime,dont_load_bitmap 0 2
/dev/cdrom /mnt/cdrom iso9660 noauto,ro,user 0 0 |
how does that look?
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