Missing HD Space (?), partition questions

funaroma · 12-02-2004, 08:21 AM

Our client recently purchased a Dell PowerEdge 700 with RedHat 9 Enterprise and an 80GB RAID 1 SATA array.

Dell preconfigured the RAID array partitions as follows:

Code:

Disk /dev/sda: 79.9 GB, 79965323264 bytes
255 heads, 63 sectors/track, 9721 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
 
   Device Boot    Start       End    Blocks   Id  System
/dev/sda1             1         5     40131   de  Dell Utility - something for Dell
/dev/sda2             6       332   2626627+  83  Linux - mounted as /home
/dev/sda3   *       333       357    200812+  83  Linux - boot partition
/dev/sda4           358      9721  75216330    f  Win95 Ext'd (LBA) - ext part:
/dev/sda5           358      1631  10233373+  83  Linux - mounted as /usr
/dev/sda6          1632      1761   1044193+  82  Linux swap - swap part
/dev/sda7          1762      1892   1052226   83  Linux - mounted as /tmp
/dev/sda8          1893      2153   2096451   83  Linux - mounted as /
/dev/sda9          2154      3427  10233373+  83  Linux - mounted as /var

NOTE:  After sda9 there is a whopping 48.2GB of FREE SPACE!

The partitions seem to make sense, and follow some best practices rules.... though for some reason they placed the HOME partition on SDA2, which is only 2.5GB, and left an entire 48.2GB completely unpartitioned. This "free space" will become sda10.

QUESTIONS:

-- The system has recognized the drive array as 80GB, but totalling up the partition space I see in the report get a sum of only 74.2. Is this correct, or am I missing some space?

-- HOME is where I've chosen to place (leave) the individual user folders, which are also Samba shares. I am also placing some additional Samba shares under the HOME filesystem. I am, for obvious reasons, going to move all these directories under HOME to the 48.2GB of space, which was wasted/unavailable before. What do you think I should do with the space in SDA2, which is around 2.5GB?

-- Is there a reason I should NOT mount sda10 into /HOME and have all user directories/shares there, and use sda2 for something else?

-- Explain why the "root" (/) partition has to have so much space?

-- Can anyone provide a good reason why, when it's all one drive anyway, there needs to be an extended partition at all? Why not just place all partitions directly, instead of having sda4 hold sda5-9? Is there a limitation on the number of partitions somewhere?

-- Why does sda4 show as a Win95 extended partition? Is this really a "microsoft thing"? Why?

-- Aside from recovering the 48GB of free space, would you change the overall partition schema on this box? How and why?

Thanks for taking the time to read my long post!

michaelk · 12-02-2004, 09:03 AM

An extended partition allows one to create more then 4 partitions. When the first PC HDs came on the market one could only have 4 partitions. This became a limitation when hard drive grew in size
and so the extended / logical scheme was developed. The original 4 partitions are now called primary partitions. To create more then 4 one of the primaries is designated as an extended. An extended partition in a nutshell is a container for the logical drives. If you search the web you can find more information on the subject.

An IDE can have up to 64 partitions and a SCSI drive 16.

You can create a sda10 and move your existing /home to the new partition. Partitioning is a matter of personal preference.

huibert.alblas · 12-02-2004, 09:09 AM

Many questions about partitions, here it goes:

Quote:

-- The system has recognized the drive array as 80GB, but totalling up the partition space I see in the report get a sum of only 74.2. Is this correct, or am I missing some space?

Yes, blocks are not Gigabytes, thats why it does not ad up....

Quote:

-- HOME is where I've chosen to place (leave) the individual user folders, which are also Samba shares. I am also placing some additional Samba shares under the HOME filesystem. I am, for obvious reasons, going to move all these directories under HOME to the 48.2GB of space, which was wasted/unavailable before. What do you think I should do with the space in SDA2, which is around 2.5GB?

You can mount /var/spool to it, or /tmp, or use it as extra swap and use the tmpfs filesystem for tmp, or .....

Quote:

-- Is there a reason I should NOT mount sda10 into /HOME and have all user directories/shares there, and use sda2 for something else?

no.

Quote:

-- Explain why the "root" (/) partition has to have so much space?

It is the way the admin has partitioned it :-)

Quote:

-- Can anyone provide a good reason why, when it's all one drive anyway, there needs to be an extended partition at all? Why not just place all partitions directly, instead of having sda4 hold sda5-9? Is there a limitation on the number of partitions somewhere?

For historical reasons only 4 primary partitions are allowed, you can have more partitons in a extended partiton.

Quote:

-- Why does sda4 show as a Win95 extended partition? Is this really a "microsoft thing"? Why?

The extended partitiion has a text label with microsoft in it, who cares?
It won't affect you in any way.

Quote:

-- Aside from recovering the 48GB of free space, would you change the overall partition schema on this box? How and why?

Is this a test or something?
I'm not that good prepared.
But yes, I would put /, /usr and /var on one single partion,
unless we are talking about a mail or database server, then I would put /var on a different drive altogether.
Because /var and /var/spool are written to and read from many times more the the rest of the system.
If the disk containing /var goes bad you can simply replace it, without affecting much of the rest of the system.

Second you'll have /tmp and SWAP on different drives then /var, which will speedup concurrent reads under load significaly.