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Home > Archive > Red Hat Networking > January 2004 > Re: Why partition a Lunux system? The real deal !!!
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Re: Why partition a Lunux system? The real deal !!!
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| Lamar Thomas 2004-01-23, 7:42 pm |
| I saw the following in a post about "inodes". It was enough to make me
re-think partitions. If this is right, then you should "almost" always
partition your drive with more then one partition!
**********************
Dear Out of Inodes.
The version of the Berkeley Fast File system used by the
ULTRIX Operating System has a limit of 2048 inodes per
cylinder group. This limit is the constant MAXIPG in the
include file /usr/include/ufs/fs.h.
When newfs/mkfs runs it attempts to allocate enough inodes
so that there are enough for an average file size of 2 KB.
(bytes per inode = 2048). When there are enough cylinder
groups this is easy. In fact if the cylinder group is small
enough, it may not get close to the MAXIPG limit.
But over the years, disks have gotten bigger. They have
more cylinders, more tracks and the tracks have more sectors.
As a result cylinder groups are larger and it's hard to
allocate enough inodes to meet the 2048 bytes per inode
limit, with only MAXIPG available. Since MAXIPG is fixed
the affective average file size goes up.
On a News spool tree, the average file probably is around
or less than 2 KB. As a result, these large cylinder disks
don't have enough inodes for the typical, and more importantly
you can't get more, since you're already at the MAXIPG limit.
At least not easily.
But there are some solutions available...
Theme of solutions:
Inodes are allocated on a cylinder group basis.
Want more inodes, use more cylinder groups.
1. Use fewer cylinders per group, thus getting more groups.
See the -c option of newfs(8).
2. Lie about the geometry. If the track length or tracks
per cylinder is nice factorable number, reduce one to
increase the effective number of cylinders. By playing
games with the factors of the geometry you manage to keep
the geometry approximately the same.
For some disks this may not matter and you can invent whatever
lie you want. For example; the RZ58 uses zoned based recording
(banding). Depending on where you are on the disk, there will
more or less sectors per track. The single geometry presented
by ULTRIX is a convent lie.
********************************
From what I understand here is that the number of inodes are alacated based
on each partition. The more partitions you have then the more inodes you
have.
Lamar
"Lamar Thomas" <na@na.net> wrote in message
news:3ptwb.1670253$Of.247919@news.easynews.com...quote:
> In this day of 80+ GB IDE HDs why should anyone partition the drive into
> more then one partition like: (/, /boot/, /usr, /usr/local, /home, /etc,
> /opt)? What is the benefit? Why not just / and swap? It seems like it's
> just a hold over from the days of smaller HDs. Any feedback?
>
> Thanks,
>
> Lamar
>
>
| |
| Lamar Thomas 2004-01-23, 7:42 pm |
| I saw the following in a post about "inodes". It was enough to make me
re-think partitions. If this is right, then you should "almost" always
partition your drive with more then one partition!
**********************
Dear Out of Inodes.
The version of the Berkeley Fast File system used by the
ULTRIX Operating System has a limit of 2048 inodes per
cylinder group. This limit is the constant MAXIPG in the
include file /usr/include/ufs/fs.h.
When newfs/mkfs runs it attempts to allocate enough inodes
so that there are enough for an average file size of 2 KB.
(bytes per inode = 2048). When there are enough cylinder
groups this is easy. In fact if the cylinder group is small
enough, it may not get close to the MAXIPG limit.
But over the years, disks have gotten bigger. They have
more cylinders, more tracks and the tracks have more sectors.
As a result cylinder groups are larger and it's hard to
allocate enough inodes to meet the 2048 bytes per inode
limit, with only MAXIPG available. Since MAXIPG is fixed
the affective average file size goes up.
On a News spool tree, the average file probably is around
or less than 2 KB. As a result, these large cylinder disks
don't have enough inodes for the typical, and more importantly
you can't get more, since you're already at the MAXIPG limit.
At least not easily.
But there are some solutions available...
Theme of solutions:
Inodes are allocated on a cylinder group basis.
Want more inodes, use more cylinder groups.
1. Use fewer cylinders per group, thus getting more groups.
See the -c option of newfs(8).
2. Lie about the geometry. If the track length or tracks
per cylinder is nice factorable number, reduce one to
increase the effective number of cylinders. By playing
games with the factors of the geometry you manage to keep
the geometry approximately the same.
For some disks this may not matter and you can invent whatever
lie you want. For example; the RZ58 uses zoned based recording
(banding). Depending on where you are on the disk, there will
more or less sectors per track. The single geometry presented
by ULTRIX is a convent lie.
********************************
From what I understand here is that the number of inodes are alacated based
on each partition. The more partitions you have then the more inodes you
have.
Lamar
"Lamar Thomas" <na@na.net> wrote in message
news:3ptwb.1670253$Of.247919@news.easynews.com...quote:
> In this day of 80+ GB IDE HDs why should anyone partition the drive into
> more then one partition like: (/, /boot/, /usr, /usr/local, /home, /etc,
> /opt)? What is the benefit? Why not just / and swap? It seems like it's
> just a hold over from the days of smaller HDs. Any feedback?
>
> Thanks,
>
> Lamar
>
>
| |
| Lamar Thomas 2004-01-23, 7:42 pm |
| I saw the following in a post about "inodes". It was enough to make me
re-think partitions. If this is right, then you should "almost" always
partition your drive with more then one partition!
**********************
Dear Out of Inodes.
The version of the Berkeley Fast File system used by the
ULTRIX Operating System has a limit of 2048 inodes per
cylinder group. This limit is the constant MAXIPG in the
include file /usr/include/ufs/fs.h.
When newfs/mkfs runs it attempts to allocate enough inodes
so that there are enough for an average file size of 2 KB.
(bytes per inode = 2048). When there are enough cylinder
groups this is easy. In fact if the cylinder group is small
enough, it may not get close to the MAXIPG limit.
But over the years, disks have gotten bigger. They have
more cylinders, more tracks and the tracks have more sectors.
As a result cylinder groups are larger and it's hard to
allocate enough inodes to meet the 2048 bytes per inode
limit, with only MAXIPG available. Since MAXIPG is fixed
the affective average file size goes up.
On a News spool tree, the average file probably is around
or less than 2 KB. As a result, these large cylinder disks
don't have enough inodes for the typical, and more importantly
you can't get more, since you're already at the MAXIPG limit.
At least not easily.
But there are some solutions available...
Theme of solutions:
Inodes are allocated on a cylinder group basis.
Want more inodes, use more cylinder groups.
1. Use fewer cylinders per group, thus getting more groups.
See the -c option of newfs(8).
2. Lie about the geometry. If the track length or tracks
per cylinder is nice factorable number, reduce one to
increase the effective number of cylinders. By playing
games with the factors of the geometry you manage to keep
the geometry approximately the same.
For some disks this may not matter and you can invent whatever
lie you want. For example; the RZ58 uses zoned based recording
(banding). Depending on where you are on the disk, there will
more or less sectors per track. The single geometry presented
by ULTRIX is a convent lie.
********************************
From what I understand here is that the number of inodes are alacated based
on each partition. The more partitions you have then the more inodes you
have.
Lamar
"Lamar Thomas" <na@na.net> wrote in message
news:3ptwb.1670253$Of.247919@news.easynews.com...quote:
> In this day of 80+ GB IDE HDs why should anyone partition the drive into
> more then one partition like: (/, /boot/, /usr, /usr/local, /home, /etc,
> /opt)? What is the benefit? Why not just / and swap? It seems like it's
> just a hold over from the days of smaller HDs. Any feedback?
>
> Thanks,
>
> Lamar
>
>
| |
| Lamar Thomas 2004-01-23, 7:48 pm |
| I saw the following in a post about "inodes". It was enough to make me
re-think partitions. If this is right, then you should "almost" always
partition your drive with more then one partition!
**********************
Dear Out of Inodes.
The version of the Berkeley Fast File system used by the
ULTRIX Operating System has a limit of 2048 inodes per
cylinder group. This limit is the constant MAXIPG in the
include file /usr/include/ufs/fs.h.
When newfs/mkfs runs it attempts to allocate enough inodes
so that there are enough for an average file size of 2 KB.
(bytes per inode = 2048). When there are enough cylinder
groups this is easy. In fact if the cylinder group is small
enough, it may not get close to the MAXIPG limit.
But over the years, disks have gotten bigger. They have
more cylinders, more tracks and the tracks have more sectors.
As a result cylinder groups are larger and it's hard to
allocate enough inodes to meet the 2048 bytes per inode
limit, with only MAXIPG available. Since MAXIPG is fixed
the affective average file size goes up.
On a News spool tree, the average file probably is around
or less than 2 KB. As a result, these large cylinder disks
don't have enough inodes for the typical, and more importantly
you can't get more, since you're already at the MAXIPG limit.
At least not easily.
But there are some solutions available...
Theme of solutions:
Inodes are allocated on a cylinder group basis.
Want more inodes, use more cylinder groups.
1. Use fewer cylinders per group, thus getting more groups.
See the -c option of newfs(8).
2. Lie about the geometry. If the track length or tracks
per cylinder is nice factorable number, reduce one to
increase the effective number of cylinders. By playing
games with the factors of the geometry you manage to keep
the geometry approximately the same.
For some disks this may not matter and you can invent whatever
lie you want. For example; the RZ58 uses zoned based recording
(banding). Depending on where you are on the disk, there will
more or less sectors per track. The single geometry presented
by ULTRIX is a convent lie.
********************************
From what I understand here is that the number of inodes are alacated based
on each partition. The more partitions you have then the more inodes you
have.
Lamar
"Lamar Thomas" <na@na.net> wrote in message
news:3ptwb.1670253$Of.247919@news.easynews.com...quote:
> In this day of 80+ GB IDE HDs why should anyone partition the drive into
> more then one partition like: (/, /boot/, /usr, /usr/local, /home, /etc,
> /opt)? What is the benefit? Why not just / and swap? It seems like it's
> just a hold over from the days of smaller HDs. Any feedback?
>
> Thanks,
>
> Lamar
>
>
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