Re: gjournal: journaled slices vs. journaled partitions

2008-11-04 Thread Volodymyr Kostyrko

Carl wrote:

Volodymyr Kostyrko wrote:

I have some setups were gjournal was put on device rather the on 
partition, i.e.:


[umgah] ~ gmirror status
  NameStatus  Components
mirror/umgah0  COMPLETE  ad0
  ad1
[umgah] ~ gjournal status
  Name  Status  Components
mirror/umgah0.journal N/A  mirror/umgah0
[umgah] ~ glabel status
 Name  Status  Components
   ufs/umgah0root N/A  mirror/umgah0.journala
label/umgah0swap N/A  mirror/umgah0.journalb
ufs/umgah0usr N/A  mirror/umgah0.journald
ufs/umgah0var N/A  mirror/umgah0.journale


Does the above suggest that you've ended up with individual journal 
providers for each partition anyway? If so, where are they and have you 
really achieved anything functionally different? Are they at the end of 
their individually associated partitions or all together somewhere else? 
Has the ill-advised journaled small partition issue been successfully 
overcome through what you've done?


First, there is only one journal - for /dev/mirror/umgah0 and it is 
named /dev/mirror/umgah0.journal. Anything else is just a bsdlabel 
partitions, there are four of 'em.





[umgah] ~ mount
/dev/ufs/umgah0root on / (ufs, asynchronous, local, noatime, gjournal)
devfs on /dev (devfs, local)
/dev/md0 on /tmp (ufs, asynchronous, local)
/dev/ufs/umgah0var on /var (ufs, asynchronous, local, noatime, gjournal)
/dev/ufs/umgah0usr on /usr (ufs, asynchronous, local, noatime, gjournal)
devfs on /var/named/dev (devfs, local)

And yes, mirror autosynchronization is turned off, gjournal takes care 
of that too.


It's not stated in manual, but gjournal is typically transparent for 
any type of access, just in case of UFS file system is marked as 
journaled so any metadata writes can be distinguished from data 
writes. Without that gjournal does literally nothing.


And what does this mean for your swap partition?


Just nothing, it's just swap. It can't be journaled.


Laszlo Nagy wrote earlier:

Another tricky question: why would you journal a SWAP partition?


Volodymyr, does your assertion that gjournal does nothing when a file 
system is not UFS mean that there is no penalty with regard to your swap 
partition despite the existence of mirror/umgah0.journalb?


I haven't seen any perfomance decrease in this configuration. And 
according to manual and articles about gjournal it should work this way.


Any chance you'd like to share your command sequence for constructing 
your gmirror'd and gjournal'd filesystem, Volodymyr? :-)


If we have two disks (ad0, ad1) it should look like this:

 gmirror label -b load -n umgah0 ad1

We are getting all drive gmirrored without synchronization (we don't 
need it - journal would take care of any discrepancies) and with load 
balance (load was fixed not so long ago in stable and should be fine to 
go with).


 gjournal label mirror/umgah0

We are creating a journal on top of our gmirror. It eats 1G from the end 
of the disks and gives us the rest to use.


 bsdlabel -wB mirror/umgah0.journal

We are writing the standard bsdlabel to the disk and making it bootable. 
After that we will get one partition 'a'.


spam
Yes, no fdisk. I don't think this old piece of rough junk is ever needed 
on machine running FreeBSD solely. It just takes space, it requires 
compatibility to forgotten-and-abandoned standards and gives nothing 
more. You have your server dual-booting Windows or Linux? This is the 
only case you need fdisk for.

/spam

 bsdlabel -e mirror/umgah0.journal

Now we are splitting our journal to some partitions. I did it this way:

# /dev/mirror/umgah0.journal:
8 partitions:
#size   offsetfstype   [fsize bsize bps/cpg]
  a:   524288   164.2BSD
  b: 16777216   *  swap
  c: 7793256140unused0 0 # raw part, 
don't edit

  d: 33554432 *4.2BSD
  e: * *4.2BSD

After that we can format this filesystems:

 newfs -J -L umgah0root /dev/mirror/umgah0.journala
 newfs -J -L umgah0var /dev/mirror/umgah0.journald
 newfs -J -L umgah0usr /dev/mirror/umgah0.journale

And label the swap:

 glabel label umgah0swap /dev/mirror/umgah0.journalb

You can skip all this glabel thing, I just prefer to have slim fstab, as 
slim as possible.


fstab
/dev/label/umgah0swap none swap sw 0 0

md /tmp mfs rw,-s1024m,-S,-oasync 0 0

/dev/ufs/umgah0root / ufs rw,async,noatime 0 1
/dev/ufs/umgah0var /var ufs rw,async,noatime 0 2
/dev/ufs/umgah0usr /usr ufs rw,async,noatime 0 2
/fstab

There's a lot more here to describe from moving system to newly created 
partitions to inserting and rebuilding our first disk to gmirror. All 
this issues are described in handbook or other articles found on the net.


--
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Re: gjournal: journaled slices vs. journaled partitions

2008-11-04 Thread Gabriel Lavoie
Hello,
 I built a similar setup last weekend on a new home server with two
500GB drives. I didn't want to only put gmirror and have full drives rebuild
on power failure/reset on the system. I was told that putting bsdlabels on a
gjournal provider wasn't a good idea but I have yet to have an answer about
why... I went with this setup anyway and I made some reset tests to see what
happens on reboot and everything always went fine.

When building this setup I got one big problem. If the root filesystem (/)
was on a gjournal provider, an unclean shutdown when data was being written
on the disk rendered the system completely unbootable. I got this message:

GEOM_MIRROR: Device mirror/gm launched (2/2)
GEOM_JOURNAL: Journal 3672855181: mirror/gma contains data.
GEOM_JOURNAL: Journal 3672855181: mirror/gma contains journal.
GEOM_JOURNAL: Journal 3868799910: mirror/gmd contains data.
GEOM_JOURNAL: Journal 3868799910: mirror/gmd contains journal.
GEOM_JOURNAL: Journal mirror/gmd consistent.
Trying to mount root from ufs:/dev/mirror/gm.journal

Manual root filesystem specification:
fstype:device  Mount device using filesystem fstype
   eg. ufs:da0s1a
? List valid disk boot devices
empty line  Abort manual input


mountroot ?

List of GEOM managed disk devices:
 mirror/gmd.journal mirror/gmd mirror/gmc mirror/gma mirror/gm ad10s1c
ad10s1b ad8s1c ad8s1b ad10s2 ad10s1 ad8s1 ad10 ad8 acd0


As you can see, in the proposed list of disk devices devices to boot on,
mirror/gm.journala is absent. As I and Ivan Voras, that I contacted about
this problem, found, the GEOM_JOURNAL thread that is supposed to mark the
journal consistent takes too much time to do it with the root filesystem's
provider and the kernel try to mount a device that doesn't yet exist. A bug
report has been opened about this problem. For my final setup I decided to
put the root filesystem on a separate mirrorred slice of 1GB. Since this
slice isn't often written on, not many rebuilds should occur in case of
power failure. And I made my power failure test by hitting the reset
button while writing data on this filesystem and the rebuild on 1GB doesn't
takes too much time (at most 20-30 seconds).

Now I have the question. Why the load algorith wasn't recommended? Is it
fixed in 7.0-RELEASE-p5?

Here is my complete setup that seems to boot correctly every times I made my
reset tests while writing data on each filesystems. The 2GB gjournal
provider is directly on the mirror provider for all mirrored filesystems
exept the root one and I made my bsd labels on the gjournal provider,
instead of creating a journal for every filesystem.


[EMAIL PROTECTED] ~]# cat /etc/fstab
# DeviceMountpoint  FStype  Options Dump
Pass#
/dev/ad10s1bnoneswapsw  0   0
/dev/ad8s1b noneswapsw  0   0
/dev/mirror/root/   ufs rw  1   1
/dev/ufs/usr/usrufs rw,async2   2
/dev/ufs/var/varufs rw,async2   2
/dev/ufs/tmp/tmpufs rw,async2   2
/dev/ufs/home   /home   ufs rw,async2   2
/dev/ufs/data   /mnt/data   ufs rw,async2   2
/dev/acd0   /cdrom  cd9660  ro,noauto   0   0


[EMAIL PROTECTED] ~]# mount
/dev/mirror/root on / (ufs, local, soft-updates)
devfs on /dev (devfs, local)
/dev/ufs/usr on /usr (ufs, asynchronous, local, gjournal)
/dev/ufs/var on /var (ufs, asynchronous, local, gjournal)
/dev/ufs/tmp on /tmp (ufs, asynchronous, local, gjournal)
/dev/ufs/home on /home (ufs, asynchronous, local, acls, gjournal)
/dev/ufs/data on /mnt/data (ufs, asynchronous, local, acls, gjournal)


[EMAIL PROTECTED] ~]# glabel status
Name  Status  Components
 ufs/usr N/A  mirror/data.journald
 ufs/var N/A  mirror/data.journale
 ufs/tmp N/A  mirror/data.journalf
ufs/home N/A  mirror/data.journalg
ufs/data N/A  mirror/data.journalh


[EMAIL PROTECTED] ~]# gjournal list
Geom name: gjournal 372943514
ID: 372943514
Providers:
1. Name: mirror/data.journal
   Mediasize: 495810966528 (462G)
   Sectorsize: 512
   Mode: r5w5e11
Consumers:
1. Name: mirror/data
   Mediasize: 497958450688 (464G)
   Sectorsize: 512
   Mode: r1w1e1
   Jend: 497958450176
   Jstart: 495810966528
   Role: Data,Journal


[EMAIL PROTECTED] ~]# gmirror list
Geom name: data
State: COMPLETE
Components: 2
Balance: split
Slice: 4096
Flags: NOFAILSYNC
GenID: 0
SyncID: 1
ID: 990032118
Providers:
1. Name: mirror/data
   Mediasize: 497958450688 (464G)
   Sectorsize: 512
   Mode: r1w1e1
Consumers:
1. Name: ad8s2
   Mediasize: 497958451200 (464G)
   Sectorsize: 512
   Mode: r1w1e1
   State: ACTIVE
   Priority: 0
   Flags: HARDCODED
   GenID: 0
   SyncID: 1
   ID: 235591066
2. 

Re: gjournal: journaled slices vs. journaled partitions

2008-11-04 Thread Gabriel Lavoie
2008/11/4 Volodymyr Kostyrko [EMAIL PROTECTED]

 2008/11/4 Gabriel Lavoie [EMAIL PROTECTED]:
  When building this setup I got one big problem. If the root filesystem
 (/)
  was on a gjournal provider, an unclean shutdown when data was being
 written
  on the disk rendered the system completely unbootable. I got this
 message:
 
  GEOM_MIRROR: Device mirror/gm launched (2/2)
  GEOM_JOURNAL: Journal 3672855181: mirror/gma contains data.
  GEOM_JOURNAL: Journal 3672855181: mirror/gma contains journal.
  GEOM_JOURNAL: Journal 3868799910: mirror/gmd contains data.
 
  GEOM_JOURNAL: Journal 3868799910: mirror/gmd contains journal.
  GEOM_JOURNAL: Journal mirror/gmd consistent.

 Just one thing - you have two separate journaled partitions, one
 journal per one partition.


Yes, this is the test setup I made with one journal for / and one journal
for /usr. Only an unclean journal on / rendered the journal unbootable. An
unclean journal on /usr gave me no problem.

If I put the journal on the slice level, with the root filesystem over the
journal. Resetting the system while writing data on any filesystem causes
the problem as the journal is shared to the root filesystem too.




  Trying to mount root from ufs:/dev/mirror/gm.journal
 
  Manual root filesystem specification:
  fstype:device  Mount device using filesystem fstype
 
 eg. ufs:da0s1a
  ? List valid disk boot devices
  empty line  Abort manual input
 
 
  mountroot ?
 
  List of GEOM managed disk devices:
 
   mirror/gmd.journal mirror/gmd mirror/gmc mirror/gma mirror/gm
 ad10s1c
  ad10s1b ad8s1c ad8s1b ad10s2 ad10s1 ad8s1 ad10 ad8 acd0
 
  As you can see, in the proposed list of disk devices devices to boot on,
  mirror/gm.journala is absent. As I and Ivan Voras, that I contacted
 about
  this problem, found, the GEOM_JOURNAL thread that is supposed to mark the
  journal consistent takes too much time to do it with the root
 filesystem's
  provider and the kernel try to mount a device that doesn't yet exist. A
 bug
  report has been opened about this problem. For my final setup I decided
 to
  put the root filesystem on a separate mirrorred slice of 1GB. Since this
  slice isn't often written on, not many rebuilds should occur in case of
  power failure. And I made my power failure test by hitting the reset
  button while writing data on this filesystem and the rebuild on 1GB
 doesn't
  takes too much time (at most 20-30 seconds).

 Good to hear it, i've fallen for that too, but the machine isn't
 powercycled at all and runs on guaranteed power. I had the similar
 problems with described setup on virtual test machine too, yet
 entering anything at mountroot prompt gave gjournal a chance to keep
 up and needed partition comes up eventually... I didn't reported that,
 thought it was a virtual machine issue.


Same thing here, I had a backup installation on another slice and when I
gave this one on the prompt, as soon as I hit Enter, GEOM_JOURNAL was
marking the journal consistent. I'm happy to hear that I'm not the only one
that had this problem. As for my setup. I put / on its own 1GB mirrored
slice with auto-synchronization and soft-updates and I put the other
filesystems (/home /usr /var /tmp) on a second fully mirrored/journalised
slice (with the journal at the slice level), with auto-synchronization on
power failure turned off and async mount option.

As for the bug report, I consider this is an easily reproductible bug and I
hope it will be solved soon! :)



  Now I have the question. Why the load algorith wasn't recommended? Is
 it
  fixed in 7.0-RELEASE-p5?

 Nope...

 http://www.freebsd.org/cgi/query-pr.cgi?pr=113885

 --
 Sphinx of black quartz judge my vow.



Gabriel

-- 
Gabriel Lavoie
[EMAIL PROTECTED]
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Re: gjournal: journaled slices vs. journaled partitions

2008-11-04 Thread Volodymyr Kostyrko
2008/11/4 Gabriel Lavoie [EMAIL PROTECTED]:
 When building this setup I got one big problem. If the root filesystem (/)
 was on a gjournal provider, an unclean shutdown when data was being written
 on the disk rendered the system completely unbootable. I got this message:

 GEOM_MIRROR: Device mirror/gm launched (2/2)
 GEOM_JOURNAL: Journal 3672855181: mirror/gma contains data.
 GEOM_JOURNAL: Journal 3672855181: mirror/gma contains journal.
 GEOM_JOURNAL: Journal 3868799910: mirror/gmd contains data.

 GEOM_JOURNAL: Journal 3868799910: mirror/gmd contains journal.
 GEOM_JOURNAL: Journal mirror/gmd consistent.

Just one thing - you have two separate journaled partitions, one
journal per one partition.

 Trying to mount root from ufs:/dev/mirror/gm.journal

 Manual root filesystem specification:
 fstype:device  Mount device using filesystem fstype

eg. ufs:da0s1a
 ? List valid disk boot devices
 empty line  Abort manual input


 mountroot ?

 List of GEOM managed disk devices:

  mirror/gmd.journal mirror/gmd mirror/gmc mirror/gma mirror/gm ad10s1c
 ad10s1b ad8s1c ad8s1b ad10s2 ad10s1 ad8s1 ad10 ad8 acd0

 As you can see, in the proposed list of disk devices devices to boot on,
 mirror/gm.journala is absent. As I and Ivan Voras, that I contacted about
 this problem, found, the GEOM_JOURNAL thread that is supposed to mark the
 journal consistent takes too much time to do it with the root filesystem's
 provider and the kernel try to mount a device that doesn't yet exist. A bug
 report has been opened about this problem. For my final setup I decided to
 put the root filesystem on a separate mirrorred slice of 1GB. Since this
 slice isn't often written on, not many rebuilds should occur in case of
 power failure. And I made my power failure test by hitting the reset
 button while writing data on this filesystem and the rebuild on 1GB doesn't
 takes too much time (at most 20-30 seconds).

Good to hear it, i've fallen for that too, but the machine isn't
powercycled at all and runs on guaranteed power. I had the similar
problems with described setup on virtual test machine too, yet
entering anything at mountroot prompt gave gjournal a chance to keep
up and needed partition comes up eventually... I didn't reported that,
thought it was a virtual machine issue.

 Now I have the question. Why the load algorith wasn't recommended? Is it
 fixed in 7.0-RELEASE-p5?

Nope...

http://www.freebsd.org/cgi/query-pr.cgi?pr=113885

-- 
Sphinx of black quartz judge my vow.
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Re: gjournal: journaled slices vs. journaled partitions

2008-11-04 Thread Volodymyr Kostyrko

Carl wrote:

So how do I achieve per-slice journaling instead of per-partition?
The docs only says this: gjournal only supports UFS2. It does not 
specifically say that you cannot have per-slice journaling. However, 
since you could have other filesystems on your slice, I bet that slice 
based journaling is not supported.


I thought I read somewhere that because gjournal is block based and not 
really part of the filesystem, that it could easily be extended for any 
other filesystem. My imagination said that gjournal was probably 
therefore only temporarily limited to a slice full of UFS partitions. 
Anyone know for sure?


gjournal needs to know what what data is actually metadata. In case of 
UFS the -J flag given to newfs tells system that using this fs we should 
mark metadata for gjournal use.



Another tricky question: why would you journal a SWAP partition?


Well, I don't really want to, but how big does a partition like /var 
have to be before it's no longer ill-advised to journal it individually? 
A fair bit of writing can occur in /var and the scenario my server will 
occupy has me concerned about inglorious shutdowns.


What are the actual reasons for why journaling a small partition is 
considered a bad idea?


Journal needs to bee big enough to amass all modifications. By default 
it's 1G. Just compare this to the size of your /var.


--
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Re: gjournal: journaled slices vs. journaled partitions

2008-10-21 Thread Carl

Laszlo Nagy wrote:

So how do I achieve per-slice journaling instead of per-partition?
The docs only says this: gjournal only supports UFS2. It does not 
specifically say that you cannot have per-slice journaling. However, 
since you could have other filesystems on your slice, I bet that slice 
based journaling is not supported.


I thought I read somewhere that because gjournal is block based and not 
really part of the filesystem, that it could easily be extended for any 
other filesystem. My imagination said that gjournal was probably 
therefore only temporarily limited to a slice full of UFS partitions. 
Anyone know for sure?



Another tricky question: why would you journal a SWAP partition?


Well, I don't really want to, but how big does a partition like /var 
have to be before it's no longer ill-advised to journal it individually? 
A fair bit of writing can occur in /var and the scenario my server will 
occupy has me concerned about inglorious shutdowns.


What are the actual reasons for why journaling a small partition is 
considered a bad idea?


Carl / K0802647

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Re: gjournal: journaled slices vs. journaled partitions

2008-10-21 Thread Volodymyr Kostyrko

Carl wrote:
My goal is to build a 2-disk server configured with gmirror and gjournal 
for maximum reliability. There will never be a second operating system 
on the system, but I prefer not to freak out any non-FreeBSD repair 
tools that might be used, so I will use compatibility instead of 
dangerously dedicated mode. This means I need one slice, but see no 
reason for more. Inside that one slice will be the usual array of 
partitions (ie. /, swap, /var, /tmp, /usr, /data).


Now, I think gmirror allows me to mirror the entire drive rather than 
forcing me to do per-slice or even per-partition mirroring. I'm looking 
for the simplest in-field replacement procedure when one of the drives 
dies and I imagine a whole drive mirror achieves this. Am I right?


gjournal, OTOH, has me really confused. The man page for gjournal(8) 
specifically does not recommend that small partitions be journaled. I 
assume that's because the journal provider rivals the partition in size 
and is therefore overhead heavy. It seems to me, though, that if I can 
journal the slice as a whole instead of per-partition journaling, that 
there will essentially then be only one journal provider for the 
combination of all partitions (ie. slice) and that the aforementioned 
overhead becomes minor. Having smaller partitions included in journaling 
 seems like a good thing to me. So how do I achieve per-slice journaling 
instead of per-partition? Every time I read up on someone else's 
gjournal implementation, it seems to end with adding partition.journal 
entries to /etc/fstab. Am I trying to achieve the impossible or 
ill-advised here?


I have some setups were gjournal was put on device rather the on 
partition, i.e.:


[umgah] ~ gmirror status
 NameStatus  Components
mirror/umgah0  COMPLETE  ad0
 ad1
[umgah] ~ gjournal status
 Name  Status  Components
mirror/umgah0.journal N/A  mirror/umgah0
[umgah] ~ glabel status
Name  Status  Components
  ufs/umgah0root N/A  mirror/umgah0.journala
label/umgah0swap N/A  mirror/umgah0.journalb
   ufs/umgah0usr N/A  mirror/umgah0.journald
   ufs/umgah0var N/A  mirror/umgah0.journale
[umgah] ~ mount
/dev/ufs/umgah0root on / (ufs, asynchronous, local, noatime, gjournal)
devfs on /dev (devfs, local)
/dev/md0 on /tmp (ufs, asynchronous, local)
/dev/ufs/umgah0var on /var (ufs, asynchronous, local, noatime, gjournal)
/dev/ufs/umgah0usr on /usr (ufs, asynchronous, local, noatime, gjournal)
devfs on /var/named/dev (devfs, local)

And yes, mirror autosynchronization is turned off, gjournal takes care 
of that too.


It's not stated in manual, but gjournal is typically transparent for any 
type of access, just in case of UFS file system is marked as journaled 
so any metadata writes can be distinguished from data writes. Without 
that gjournal does literally nothing.


--
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Re: gjournal: journaled slices vs. journaled partitions

2008-10-21 Thread Carl

Volodymyr Kostyrko wrote:

I have some setups were gjournal was put on device rather the on 
partition, i.e.:


[umgah] ~ gmirror status
  NameStatus  Components
mirror/umgah0  COMPLETE  ad0
  ad1
[umgah] ~ gjournal status
  Name  Status  Components
mirror/umgah0.journal N/A  mirror/umgah0
[umgah] ~ glabel status
 Name  Status  Components
   ufs/umgah0root N/A  mirror/umgah0.journala
label/umgah0swap N/A  mirror/umgah0.journalb
ufs/umgah0usr N/A  mirror/umgah0.journald
ufs/umgah0var N/A  mirror/umgah0.journale


Does the above suggest that you've ended up with individual journal 
providers for each partition anyway? If so, where are they and have you 
really achieved anything functionally different? Are they at the end of 
their individually associated partitions or all together somewhere else? 
Has the ill-advised journaled small partition issue been successfully 
overcome through what you've done?



[umgah] ~ mount
/dev/ufs/umgah0root on / (ufs, asynchronous, local, noatime, gjournal)
devfs on /dev (devfs, local)
/dev/md0 on /tmp (ufs, asynchronous, local)
/dev/ufs/umgah0var on /var (ufs, asynchronous, local, noatime, gjournal)
/dev/ufs/umgah0usr on /usr (ufs, asynchronous, local, noatime, gjournal)
devfs on /var/named/dev (devfs, local)

And yes, mirror autosynchronization is turned off, gjournal takes care 
of that too.


It's not stated in manual, but gjournal is typically transparent for any 
type of access, just in case of UFS file system is marked as journaled 
so any metadata writes can be distinguished from data writes. Without 
that gjournal does literally nothing.


And what does this mean for your swap partition?

Laszlo Nagy wrote earlier:

Another tricky question: why would you journal a SWAP partition?


Volodymyr, does your assertion that gjournal does nothing when a file 
system is not UFS mean that there is no penalty with regard to your swap 
partition despite the existence of mirror/umgah0.journalb?


Any chance you'd like to share your command sequence for constructing 
your gmirror'd and gjournal'd filesystem, Volodymyr? :-)


Carl / K0802647
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gjournal: journaled slices vs. journaled partitions

2008-10-20 Thread Carl
My goal is to build a 2-disk server configured with gmirror and gjournal 
for maximum reliability. There will never be a second operating system 
on the system, but I prefer not to freak out any non-FreeBSD repair 
tools that might be used, so I will use compatibility instead of 
dangerously dedicated mode. This means I need one slice, but see no 
reason for more. Inside that one slice will be the usual array of 
partitions (ie. /, swap, /var, /tmp, /usr, /data).


Now, I think gmirror allows me to mirror the entire drive rather than 
forcing me to do per-slice or even per-partition mirroring. I'm looking 
for the simplest in-field replacement procedure when one of the drives 
dies and I imagine a whole drive mirror achieves this. Am I right?


gjournal, OTOH, has me really confused. The man page for gjournal(8) 
specifically does not recommend that small partitions be journaled. I 
assume that's because the journal provider rivals the partition in size 
and is therefore overhead heavy. It seems to me, though, that if I can 
journal the slice as a whole instead of per-partition journaling, that 
there will essentially then be only one journal provider for the 
combination of all partitions (ie. slice) and that the aforementioned 
overhead becomes minor. Having smaller partitions included in journaling 
 seems like a good thing to me. So how do I achieve per-slice 
journaling instead of per-partition? Every time I read up on someone 
else's gjournal implementation, it seems to end with adding 
partition.journal entries to /etc/fstab. Am I trying to achieve the 
impossible or ill-advised here?


Carl / K0802647

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Re: gjournal: journaled slices vs. journaled partitions

2008-10-20 Thread Laszlo Nagy



So how do I achieve per-slice journaling instead of per-partition?
The docs only says this: gjournal only supports UFS2. It does not 
specifically say that you cannot have per-slice journaling. However, 
since you could have other filesystems on your slice, I bet that slice 
based journaling is not supported.


Consider this: how would you journal an NTFS file system (and then boot 
windows after an unclean shutdown?) Another tricky question: why would 
you journal a SWAP partition?


Best,

  Laszlo

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