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Old 03-07-2009, 08:52 PM
Sven Joachim
 
Default Advice about ext3, please

On 2009-03-07 21:30 +0100, Paul E Condon wrote:

> I'd like some confirmation, or refutation, of some reasoning:
>
> I have a USB external hard drive. It came with vfat fs, but I want to
> write an ext2/3 fs on it. All my internal HD are ext3, but should this
> one be ext3, also?

That would be okay, unless you need to access it from systems that
cannot read ext3.

> Doesn't ext3 essentially write everything twice,
> first to the journal, and then to the actual target location?

No, unless you use the mount option data=journal. See the "Mount
options for ext3" section in mount(8).

> This is OK with an internal bus interface from the CPU to the HD, but
> USB is not so fast. So I think I should not use ext3 for this HD. Is
> this correct?

AFAIK there are no special disadvantages in using ext3 for external hard
disks.

Sven


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Old 03-08-2009, 04:58 AM
Steven Demetrius
 
Default Advice about ext3, please

Paul E Condon wrote:

I'd like some confirmation, or refutation, of some reasoning:

I have a USB external hard drive. It came with vfat fs, but I want to
write an ext2/3 fs on it. All my internal HD are ext3, but should this
one be ext3, also? Doesn't ext3 essentially write everything twice,
first to the journal, and then to the actual target location? This is
OK with an internal bus interface from the CPU to the HD, but USB is
not so fast. So I think I should not use ext3 for this HD. Is this
correct?

TIA


Basically ext3 is ext2 with Journaling. Journaling basically safe-guards
against power failure and system crashes. It is well suited for system
partitions and partitions that are being used most of the time your
computer is on.


Journaling uses significantly more disk space and does not allow for
deleted file recovery. IT uses more resources that ext2. Journaling does
not write everything twice. It keeps track of the file system which
makes recovery fast and more reliable than file systems without Journaling.


I recommend the following:

ext3 - for system partitions and data partitions which are in use most
of the time (/, /home, /var, etc. if they are separate partitions or
drives).


ext2 - for backup, removable, partitions rarely used, etc.

If your USB external is for backup or file transfers then I recommend
using the ext2 file system on it. Logic being that if your USB external
data gets corrupted then you still have a copy of the data on another
partition.


FYI:
Some people confuse backup with archiving. They will make copies of
their data and store it away until they have data problems with the
system. This is archiving.
Backup is a never ending routine whether done once a week or one a month
and also include regular data integrity checks of the backups.



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Old 03-08-2009, 05:41 AM
Lists
 
Default Advice about ext3, please

Steven Demetrius wrote:

Paul E Condon wrote:

I'd like some confirmation, or refutation, of some reasoning:

I have a USB external hard drive. It came with vfat fs, but I want to
write an ext2/3 fs on it. All my internal HD are ext3, but should this
one be ext3, also? Doesn't ext3 essentially write everything twice,
first to the journal, and then to the actual target location? This is
OK with an internal bus interface from the CPU to the HD, but USB is
not so fast. So I think I should not use ext3 for this HD. Is this
correct?

TIA


Basically ext3 is ext2 with Journaling. Journaling basically safe-guards
against power failure and system crashes. It is well suited for system
partitions and partitions that are being used most of the time your
computer is on.


Journaling uses significantly more disk space and does not allow for
deleted file recovery. IT uses more resources that ext2. Journaling does
not write everything twice. It keeps track of the file system which
makes recovery fast and more reliable than file systems without Journaling.


I recommend the following:

ext3 - for system partitions and data partitions which are in use most
of the time (/, /home, /var, etc. if they are separate partitions or
drives).


ext2 - for backup, removable, partitions rarely used, etc.

If your USB external is for backup or file transfers then I recommend
using the ext2 file system on it. Logic being that if your USB external
data gets corrupted then you still have a copy of the data on another
partition.


FYI:
Some people confuse backup with archiving. They will make copies of
their data and store it away until they have data problems with the
system. This is archiving.
Backup is a never ending routine whether done once a week or one a month
and also include regular data integrity checks of the backups.





Correction:
Journaling file system does write data twice.
ttp://en.wikipedia.org/wiki/Ext3


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Old 03-08-2009, 02:53 PM
Paul E Condon
 
Default Advice about ext3, please

On 2009-03-08_12:58:14, Steven Demetrius wrote:
> Paul E Condon wrote:
>> I'd like some confirmation, or refutation, of some reasoning:
>>
>> I have a USB external hard drive. It came with vfat fs, but I want to
>> write an ext2/3 fs on it. All my internal HD are ext3, but should this
>> one be ext3, also? Doesn't ext3 essentially write everything twice,
>> first to the journal, and then to the actual target location? This is
>> OK with an internal bus interface from the CPU to the HD, but USB is
>> not so fast. So I think I should not use ext3 for this HD. Is this
>> correct?
>>
>> TIA
>
> Basically ext3 is ext2 with Journaling. Journaling basically safe-guards
> against power failure and system crashes. It is well suited for system
> partitions and partitions that are being used most of the time your
> computer is on.
>
> Journaling uses significantly more disk space and does not allow for
> deleted file recovery. IT uses more resources that ext2. Journaling does
> not write everything twice. It keeps track of the file system which makes
> recovery fast and more reliable than file systems without Journaling.
>
> I recommend the following:
>
> ext3 - for system partitions and data partitions which are in use most of
> the time (/, /home, /var, etc. if they are separate partitions or
> drives).
>
> ext2 - for backup, removable, partitions rarely used, etc.
>
> If your USB external is for backup or file transfers then I recommend
> using the ext2 file system on it. Logic being that if your USB external
> data gets corrupted then you still have a copy of the data on another
> partition.
>
> FYI:
> Some people confuse backup with archiving. They will make copies of their
> data and store it away until they have data problems with the system. This
> is archiving.
> Backup is a never ending routine whether done once a week or one a month
> and also include regular data integrity checks of the backups.

I turned 76 last Dec. I've followed digital electronic computing since
I was in high school in late '40s. That was way back when digital
computers would seldom run for more than a few hours or a day without
crashing. Back then, people regularly ran what they called 'check
points'. These were records of the current state of the unfinished
computation in a format that was suitable for restarting the computer
after the offending vacuum tube was found and replaced. Often, the
last check point record was unreadable, whatever the recording medium,
and they had to find the last *good* check point. Then, they would
'back up' to that last good check point and resume the calculation
from that poing. Over time, the jargon has changed. The word backup
now means what was once called 'writing a check point'. Back then, I
think there was little idea of archiving as it is thought of today,
namely a permanent historical record. Check points were written onto
flaky (literally) magnetic tape, or punched paper tape. Any idea of
permanence of such records seemed rediculous.

I show my age by calling my nightly backups check points. They are
written on a separate HD on a separate computer. Now, I am working on
a system for archiving my check points onto an external HD.

Your comments are helpful reinforcement of my inclinations, but see
Sven's earlier comment. The current default for mount of ext3fs seems
not to be so costly as you or I have supposed. There is a very costly
option, but it is not the default.

Thanks.
--
Paul E Condon
pecondon@mesanetworks.net


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Old 03-08-2009, 02:57 PM
Paul E Condon
 
Default Advice about ext3, please

On 2009-03-08_13:41:53, Lists wrote:
> Steven Demetrius wrote:
>> Paul E Condon wrote:
>>> I'd like some confirmation, or refutation, of some reasoning:
>>>
>>> I have a USB external hard drive. It came with vfat fs, but I want to
>>> write an ext2/3 fs on it. All my internal HD are ext3, but should this
>>> one be ext3, also? Doesn't ext3 essentially write everything twice,
>>> first to the journal, and then to the actual target location? This is
>>> OK with an internal bus interface from the CPU to the HD, but USB is
>>> not so fast. So I think I should not use ext3 for this HD. Is this
>>> correct?
>>>
>>> TIA
>>
>> Basically ext3 is ext2 with Journaling. Journaling basically safe-guards
>> against power failure and system crashes. It is well suited for system
>> partitions and partitions that are being used most of the time your
>> computer is on.
>>
>> Journaling uses significantly more disk space and does not allow for
>> deleted file recovery. IT uses more resources that ext2. Journaling does
>> not write everything twice. It keeps track of the file system which
>> makes recovery fast and more reliable than file systems without
>> Journaling.
>>
>> I recommend the following:
>>
>> ext3 - for system partitions and data partitions which are in use most
>> of the time (/, /home, /var, etc. if they are separate partitions or
>> drives).
>>
>> ext2 - for backup, removable, partitions rarely used, etc.
>>
>> If your USB external is for backup or file transfers then I recommend
>> using the ext2 file system on it. Logic being that if your USB external
>> data gets corrupted then you still have a copy of the data on another
>> partition.
>>
>> FYI:
>> Some people confuse backup with archiving. They will make copies of
>> their data and store it away until they have data problems with the
>> system. This is archiving.
>> Backup is a never ending routine whether done once a week or one a month
>> and also include regular data integrity checks of the backups.
>>
>>
>
> Correction:
> Journaling file system does write data twice.
> ttp://en.wikipedia.org/wiki/Ext3

This is an interesting reference. I think I am convinced that journaling
in Linux is -not- a finished story.

Thanks for pointing it out.

--
Paul E Condon
pecondon@mesanetworks.net


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Old 03-09-2009, 01:17 AM
Steven Demetrius
 
Default Advice about ext3, please

Paul E Condon wrote:

On 2009-03-08_12:58:14, Steven Demetrius wrote:

Paul E Condon wrote:

I'd like some confirmation, or refutation, of some reasoning:

I have a USB external hard drive. It came with vfat fs, but I want to
write an ext2/3 fs on it. All my internal HD are ext3, but should this
one be ext3, also? Doesn't ext3 essentially write everything twice,
first to the journal, and then to the actual target location? This is
OK with an internal bus interface from the CPU to the HD, but USB is
not so fast. So I think I should not use ext3 for this HD. Is this
correct?

TIA
Basically ext3 is ext2 with Journaling. Journaling basically safe-guards
against power failure and system crashes. It is well suited for system
partitions and partitions that are being used most of the time your
computer is on.


Journaling uses significantly more disk space and does not allow for
deleted file recovery. IT uses more resources that ext2. Journaling does
not write everything twice. It keeps track of the file system which makes
recovery fast and more reliable than file systems without Journaling.


I recommend the following:

ext3 - for system partitions and data partitions which are in use most of
the time (/, /home, /var, etc. if they are separate partitions or
drives).


ext2 - for backup, removable, partitions rarely used, etc.

If your USB external is for backup or file transfers then I recommend
using the ext2 file system on it. Logic being that if your USB external
data gets corrupted then you still have a copy of the data on another
partition.


FYI:
Some people confuse backup with archiving. They will make copies of their
data and store it away until they have data problems with the system. This
is archiving.
Backup is a never ending routine whether done once a week or one a month
and also include regular data integrity checks of the backups.


I turned 76 last Dec. I've followed digital electronic computing since
I was in high school in late '40s. That was way back when digital
computers would seldom run for more than a few hours or a day without
crashing. Back then, people regularly ran what they called 'check
points'. These were records of the current state of the unfinished
computation in a format that was suitable for restarting the computer
after the offending vacuum tube was found and replaced. Often, the
last check point record was unreadable, whatever the recording medium,
and they had to find the last *good* check point. Then, they would
'back up' to that last good check point and resume the calculation
from that poing. Over time, the jargon has changed. The word backup
now means what was once called 'writing a check point'. Back then, I
think there was little idea of archiving as it is thought of today,
namely a permanent historical record. Check points were written onto
flaky (literally) magnetic tape, or punched paper tape. Any idea of
permanence of such records seemed rediculous.

I show my age by calling my nightly backups check points. They are
written on a separate HD on a separate computer. Now, I am working on
a system for archiving my check points onto an external HD.


Your comments are helpful reinforcement of my inclinations, but see
Sven's earlier comment. The current default for mount of ext3fs seems
not to be so costly as you or I have supposed. There is a very costly
option, but it is not the default.


Thanks.


Paul congratulations on your 76th and thank you for the history lessen.
It very interesting and most times funny how computer jargon evolves.


Thank you for your positive comments.

I've looked at Sven's earlier comments. If there is a concern with
compatibility with older systems then ext2 would be the way to go.


If the default mount option is to not enable write to journal then that
does reduce amount of resources used. However, journaling still requires
more disk space for file system management which in a data backup or
data transfer HD would be better used for data storage. Here I'm talking
about the journaling database used to track changes on the file system
to be used for recovery.


I don't see any advantage in using ext3 over ext2 for data backup or
data transfer. I do see some disadvantages. However in the grand scheme
of things these disadvantages maybe negligible. The main issue here is
the amount of disk space used for maintaining the file system which
affects the amount of space available for data storage.


An Internet search would be a good way to get detailed comparison on
advantages and disadvantages of ext2 and ext3.


Thanks you.
Steven


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Old 03-09-2009, 01:20 AM
Steven Demetrius
 
Default Advice about ext3, please

Paul E Condon wrote:

On 2009-03-08_13:41:53, Lists wrote:

Steven Demetrius wrote:

Paul E Condon wrote:

I'd like some confirmation, or refutation, of some reasoning:

I have a USB external hard drive. It came with vfat fs, but I want to
write an ext2/3 fs on it. All my internal HD are ext3, but should this
one be ext3, also? Doesn't ext3 essentially write everything twice,
first to the journal, and then to the actual target location? This is
OK with an internal bus interface from the CPU to the HD, but USB is
not so fast. So I think I should not use ext3 for this HD. Is this
correct?

TIA
Basically ext3 is ext2 with Journaling. Journaling basically safe-guards
against power failure and system crashes. It is well suited for system
partitions and partitions that are being used most of the time your
computer is on.


Journaling uses significantly more disk space and does not allow for
deleted file recovery. IT uses more resources that ext2. Journaling does
not write everything twice. It keeps track of the file system which
makes recovery fast and more reliable than file systems without
Journaling.


I recommend the following:

ext3 - for system partitions and data partitions which are in use most
of the time (/, /home, /var, etc. if they are separate partitions or
drives).


ext2 - for backup, removable, partitions rarely used, etc.

If your USB external is for backup or file transfers then I recommend
using the ext2 file system on it. Logic being that if your USB external
data gets corrupted then you still have a copy of the data on another
partition.


FYI:
Some people confuse backup with archiving. They will make copies of
their data and store it away until they have data problems with the
system. This is archiving.
Backup is a never ending routine whether done once a week or one a month
and also include regular data integrity checks of the backups.




Correction:
Journaling file system does write data twice.
ttp://en.wikipedia.org/wiki/Ext3


This is an interesting reference. I think I am convinced that journaling
in Linux is -not- a finished story.

Thanks for pointing it out.



Paul:

Did you take a look at the ext4 file system?

Looking very interesting. Especially deframentation.

Thank you
Steven.


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Old 03-09-2009, 02:13 AM
Paul E Condon
 
Default Advice about ext3, please

On 2009-03-09_09:20:06, Steven Demetrius wrote:
> Paul E Condon wrote:
>> On 2009-03-08_13:41:53, Lists wrote:
>>> Steven Demetrius wrote:
>>>> Paul E Condon wrote:
>>>>> I'd like some confirmation, or refutation, of some reasoning:
>>>>>
>>>>> I have a USB external hard drive. It came with vfat fs, but I want to
>>>>> write an ext2/3 fs on it. All my internal HD are ext3, but should this
>>>>> one be ext3, also? Doesn't ext3 essentially write everything twice,
>>>>> first to the journal, and then to the actual target location? This is
>>>>> OK with an internal bus interface from the CPU to the HD, but USB is
>>>>> not so fast. So I think I should not use ext3 for this HD. Is this
>>>>> correct?
>>>>>
>>>>> TIA
>>>> Basically ext3 is ext2 with Journaling. Journaling basically
>>>> safe-guards against power failure and system crashes. It is well
>>>> suited for system partitions and partitions that are being used
>>>> most of the time your computer is on.
>>>>
>>>> Journaling uses significantly more disk space and does not allow for
>>>> deleted file recovery. IT uses more resources that ext2. Journaling
>>>> does not write everything twice. It keeps track of the file system
>>>> which makes recovery fast and more reliable than file systems
>>>> without Journaling.
>>>>
>>>> I recommend the following:
>>>>
>>>> ext3 - for system partitions and data partitions which are in use
>>>> most of the time (/, /home, /var, etc. if they are separate
>>>> partitions or drives).
>>>>
>>>> ext2 - for backup, removable, partitions rarely used, etc.
>>>>
>>>> If your USB external is for backup or file transfers then I
>>>> recommend using the ext2 file system on it. Logic being that if
>>>> your USB external data gets corrupted then you still have a copy of
>>>> the data on another partition.
>>>>
>>>> FYI:
>>>> Some people confuse backup with archiving. They will make copies of
>>>> their data and store it away until they have data problems with the
>>>> system. This is archiving.
>>>> Backup is a never ending routine whether done once a week or one a
>>>> month and also include regular data integrity checks of the backups.
>>>>
>>>>
>>> Correction:
>>> Journaling file system does write data twice.
>>> ttp://en.wikipedia.org/wiki/Ext3
>>
>> This is an interesting reference. I think I am convinced that journaling
>> in Linux is -not- a finished story.
>>
>> Thanks for pointing it out.
>>
>
> Paul:
>
> Did you take a look at the ext4 file system?
>
> Looking very interesting. Especially deframentation.

I read the description in wikipedia. We will all be doing ext4 in near
future, I think. But for now, my project is making an archive of my
check points. For this application I think ext2 provides a tiny decrease
in overhead, for an infinitessimal increase in unreliability. For this
app., there is always the option of a total re-run of any single job.
Other issues like USB 2.0 vs USB 1.1 loom -much- larger.

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pecondon@mesanetworks.net


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Old 03-09-2009, 02:15 AM
Stefan Monnier
 
Default Advice about ext3, please

> Journaling uses significantly more disk space and does not allow for deleted
> file recovery.

Neither is true. I believe you're confusing log-structured file systems
and journalled file systems.

> ext2 - for backup, removable, partitions rarely used, etc.

ext2 is problematic for removable drives because if you remove the drive
without cleanly unmounting it you risk losing your data. So I would
recommend ext3 for such uses. Performance is rarely an issue, actually.


Stefan


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Old 03-09-2009, 02:25 AM
Celejar
 
Default Advice about ext3, please

On Sun, 08 Mar 2009 23:15:43 -0400
Stefan Monnier <monnier@iro.umontreal.ca> wrote:

...

> ext2 is problematic for removable drives because if you remove the drive
> without cleanly unmounting it you risk losing your data. So I would
> recommend ext3 for such uses. Performance is rarely an issue, actually.

I use ext3 for my external USB drive. Does this mean that I can remove
it without cleanly unmounting it and not need to worry, or do you
merely mean that I'd be less likely to lose data than if I'd use ext2?

Celejar
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