[Ayioa]

Reiser4 / reiserfs (v3.
6) thread

in this thread infos and tips have to go bit by bit to the file systems
reiser4 and reiserfs appear, to raise the achievement and more

general and special infos to Reiser4:
* Reiser4 wikipedia (english) ( en.
wikipedia.
org / wiki / Reiser4)
* Reiser4 wikipedia (in German) ( de.
wikipedia.
org / wiki / Reiser4)
* Trees in the Reiser4 file system, Part I (english) ( www.
linuxjournal.
com / article / in 6267)
* Reiser4, Part II: Designing Trees that Cache Waving (english) ( www.
linuxjournal.
com / article / in 6569)
* IV.
Symphony of pilgrim (in German) ( www.
linux magazin.
de/heft_abo/ausgaben/2004/09/iv_symphonie_von_reiser)

Reiser4 contain "features", till recently in other file systems yet had not found move:
a "Plugin" architecture, it allows to programmers, to extend the file system (later) by features, yet inkludiert are not or.
to allow it to the users to use basically different file systems with similar functions summarised under one [FIXME: add site, info, ...
]

"Dancing trees": Dance hall trees (en.
wikipedia.
org) ( en.
wikipedia.
org / wiki / Dancing_tree) [FIXME: add more info]

clear file system compression (alternatively gzip (gzip1) or lzo (lzo1)); with "clear" is meant, the fact that one can use the file system normally, it itself compresses the data and (automatically in the background) thereby, in addition, (the pilgrims file systems are known for an efficient memory management) still save place or.
even can win [FIXME: more info available?]
this feature (cryptcompress) became so much I know about Edward Shiskin developed, one more is few, the Reiser4 develops, in addition, can be chosen, whether the files should be always compressed (force); the compression should be deactivated for the file, if the compression manager finds something not compressible (ultim); the files on an adaptive algorithm should be compressed based (lattice); or normally with the help of the first 64K of the first cluster decides on it, whether the file is compressible or should be converted in extent and is treated up to the end of his existence as a normal file about unix file plugin (conv); one would still like to use the advantages from cryptcompress without compression (none)

furthermore was Reiser4 + cryptcompress the only file system under gnu / Linux, the test sums (checksumming) for all clusters from themselves support and therefore a higher data security spring needed] (at the moment in development considering btrfs guarantees [supported also compression, Test sums and more)

means what to so much like arrangement of the files according to a certain pattern Fibration: possibly are alphabetical (lexic_fibre); dot_o_fibre (the libraries / Libraries are packed up closer, so that the system boots up faster or is a matter equipping compiling faster from); the files become after 1.
Letters of the file system ending arranged or.
packed up (ext_1_fibre); nevertheless, this resembles in view of 3 letters of the file ending (ext_3_fibre)

Tail Packing (block suballocation ( en.
wikipedia.
org / wiki / Block_suballocation)),this feature already has with reiserfs v3.
X moves held.
Nevertheless, in Reiser4 one has a bigger choice between Tail Packing for all files (tails); no Tail Packing (extents); or one leaves the decision to an algorithm, he decides, whether leistungs "living" (the achievement loss amounts to about 3 5% with clear advantages: less fragmenting, more storage space, etc..
) Tail Packing for concerning (n) file (en) is worthwhile (smart) [FIXME: more info about fragmentation?]


other features of Reiser4 are:
the choice between compression (with test sums) and Not compression (unix file plugin, cryptcompress plugin)
which compression algorithm should be chosen (gzip, lzo)
which compression strategy is chosen (conv, ultim, latt, force, none)
the choice of the clusters size ("4K", "8K", "16K", "32K", "64K")
[FIXME]

abovementioned features can be given with the construction of the file system firmly d.
h.
one is able to do this without file system another to format and to lose the data (presumably) do not change any more:
mkfs.
reiser4 o
create =
compress =
compressMode =
fibration =
formatting =

a few examples, how such an equipment or.
Formatting of a Reiser4 partition could look:

mkfs.
reiser4 o create=ccreg40,compress=gzip1,compressMode=ultim,c luster=8K,fibration=lexic_fibr e,formatting=smart/dev/foo

mkfs.
reiser4 o create=ccreg40,compress=gzip1,compressMode=conv,cl uster=8K,fibration=lexic_fibre ,formatting=tails/dev/foo

mkfs.
reiser4 o create=ccreg40,compress=gzip1,compressMode=force,c luster=8K,fibration=lexic_fibr e,formatting=tails/dev/foo

mkfs.
reiser4 o create=ccreg40,compress=lzo1,cluster=8K,fibration= lexic_fibre,formatting=tails/dev/foo

in the following are performed the Mount options (the options, one can change jederseit after the Unmounten of the file system); these have to go not given; Reiser4 selects a (semi) optimum set of options for usual, they well run:
tmgr.
atom_max_size=N
tmgr.
atom_max_age=N
tmgr.
atom_max_flushers=N
tree.
cbk_cache.
nr_slots=N
flush.
relocate_threshold=N
flush.
relocate_distance=N
flush.
scan_maxnodes=N
optimal_io_size=N
bsdgroups
32bittimes
mtflush
nopseudo
dont_load_bitmap


general and special infos to reiserfs:
* en.
wikipedia.
org/wiki/ReiserFS
* The structure of the pilgrims file system (by Florian Buchholz) ( homes.
cerias.
purdue.
edu / ~ florian/reiser/reiserfs.
php)

(FIXME: needs more information, optimally from the developers at former namesys.
com, postings of Hans Reiser, etc..
)

tuning section:
to avoid around unnecessary achievement losses, if both file systems with noatime had to go,nodiratime gemountet become (info: en.
tldp.
org/LDP/solrhe/Securing Optimizing Linux RH edition v1.
3/chap6sec73.
html
Linux records information about when files were created and read modified as wave as when it what read accessed.
There is a cost associated with recording the read access time.
or on newer kerneln relatime ( lwn.
net / Articles / 244829/,http://www.
lesswatts.
org/tips/disks.
php)

tuning especially for Reiser4:

still blank!

to me time finds, to explain this completely, if I refer first to English-speaking resources:
Reiser4 Gentoo FAQ (forums.
gentoo.
org) ( forums.
gentoo.
org/viewtopic t 706171 highlight .
html)
ReiserFS tuning thread, the mother of all "ricer" threads (forums.
gentoo.
org) ( forums.
gentoo.
org/viewtopic t 707465 highlight .
html)

tuning especially for reiserfs:
then mounte dateisystem with commit=600 (these are 10 minuten)
mount option "commit=N" that sets commit interval in seconds
this is especially helpful in the laptop company, if flat switches in standby modus and not so often should start, this describes, how often on the flat one should be written

if it should go sometimes a little faster (z.
B.
to play a big backup on a backup record; however, on this occasion, the electricity supply should be guaranteed), if one can also add data=writeback
with this Mount option, with Ext 3 a performance profit
from about 10 percent, with ReiserFS up to 30 percent towards
of the Default option brings, is allowed to do the file system already in this
write journal, before all data in her destination
have arrived.
With a crash it can seem, that by him
file system check old data in files appear.
The option is
for ReiserFS only under Kernel 2.
6 available.
(Spring: Linux magazine in 2004/11 ( www.
linux magazin.
de/heft_abo/ausgaben/2004/11/qual_der_wahl?category=0))

alternatively there is still: data=ordered (standard), to read up data=journal (surest) (on: (Linux magazine in 2004/11 ( www.
linux magazin.
de/heft_abo/ausgaben/2004/11/qual_der_wahl?category=0)))

data=notail, on this occasion, is renounced the Tail packing (with newer kerneln one simply brags notail, z.
B.
* notail)
Only with ReiserFS.
ReiserFS uses empty space in blocks, around
to store in it parts of data, not in a block
fit.
The tail (English ones.
Tail) of the file is cut off
and in another block stored.
ReiserFS stores with it 10
to 20 percent more files on the same partition than, for example, Ext 3.
Because with it a light performance loss
is connected up to 5 percent, if lets itself this feature with
of the option "data=notail" switch off.
(Spring: Linux magazine in 2004/11 ( www.
linux magazin.
de/heft_abo/ausgaben/2004/11/qual_der_wahl?category=0))

more special follows later