13. Hard Drives

All hard drives have 8 partitions, that you can adjust in size. Each partition is called a slice. For slice (partition) 0 the true name would be /dev/dsk/c0t3d0s0 (the last part (s0) is the name of the slice). Let’s break down this name (or address):

*Note: some devices (targets) have two disks in them

Every time you have a device you will have two entries: one in /dev/dsk/ and one in /dev/rdsk. The following explains the nuances between them:

To see which devices numbers are being used, use the ls /dev/dsk or ls /dev/rdsk command.

For partitioning, use the following commands:

• format (this will take you to a menu (format>)) you don’t need to format the disk, just partition it
• fmthard (you will type this at the format> prompt)
• prtvtoc
• In the format menu type partition, then modify all partitions at once.

Some notes about partitioning: Partition (or slice) 2 goes from beginning to end of disk, this partition tells you how big the drive is (do not use partition 2), this is used for scripts, and to check drive size. The “free hog” partition will take up any free space and put it in this slice. Don’t pay attention to flag and tag field. Doing “all free hog” in modify will make all partitions 0 (zero). Partitioning does not effect data but will make it harder to find. Make backups before partitioning, restore backups, then reboot.

• prtvtoc – this command will print the table of volume table of contents prtvtoc [device name] i.e. prtvtoc /dev/rdsk/c0t1d0s2 will show the partition information for the named disk.
• prtvtoc /dev/rdsk/c0t1d0s2> /tmp/vtoc will save the info to a file called /tmp/vtoc
• fmthard –5 [file to put info in] [device name] - will do the same as above (i.e. fmthard –5 /tmp/vtoc /dev/rdsk/c0t1d0s2) the –5 tells fmthard command that you will name a file. The fmthard command (with –5) will take the information from prtvtoc and will create a partition table form that. install boot /usr/platfomr/sun4u/lib/fs/usf/bootblk /dev/rdsk/c0t1d0s0 will give you a bootable disk on slice 0
• df –k – reports number of free disk blocks, and shows mount points and all statistics.
• newfs [device to create a new file system to] – creates a new file system on a partition (i.e. newfs /dev/rdsk/c0t1d0s0) it will create all info needed on partition

For optimization of your hard drive you need to know the following:

1. Which partitions (file system, swap)
2. Size of each partition (df –k (shows hard disk space) , dv –sk [filename] (shows how big the sub directory is)
3. Location – put the busiest partitions in the middle

To optimize the hard disk, you need to do the following:

1. Which file system is in use now (df –k)
2. How busy is the hard drive (iostat –d10)
3. Choose new partition sizes
4. Backup all file systems (ufsdump)
5. Boot from the DC (so it doesn’t use root)
6. Repartition (format)
7. Create file system for each partition (newfs)
8. Mount the disk
9. Restore the disk
10. Edit vfstab on the hard drive
11. Reboot

There are cylinder groups (or regions) on a file system (disk)

The super block contains the following information:

1. Total number of files
2. Total amount of used space
3. Location of cylinder groups

• The cylinder block is on each cylinder block and contains same information as super block, except that it only contains cylinder information
• Cylinders are broken down in to Inodes and data groups. Inodes hold all system information for files (i.e. who a file belongs to, permissions, etc) EVERY FILE GETS AN INODE.
• Data groups hold actual data in files

To monitor your resources do the following:

• iostat> /var/adm/iolog (the /var/adm/iolog can be any file name that you want your logs stored in)
• rcp [filename1] [filename2] to copy from one place to another or to copy from one server to another, do rcp [ filename to copy] [hostname:path of where to copy].
• Then do ps –ef | nawk ‘{print $2,$5} $2 and $5 are telling the system to print the 2nd and 5th column of the ps command. This will give you some optimization numbers on your system.

Here is a sample set of partitions (you don’t want 100% of your disk allocated)

• s0 - usually root or boot information
• s1 – swap used as RAM s2 – super block (DON’T TOUCH!)
• s4 - /var (things that grow in size, i.e. logs and print queues)
• s5 – option software, /opt
• s6 – operating system (usr, UNIX System Resources)
• s7 – home directories

Partitions allow you to decide how much space you give to each thing (dividing up space)

Reasons to partition: Divide up and reserve space. Set properties (make read only, make quotas of how space a user can use). Special (s) in permission in the x (execute) field makes whoever is the owner the permissions of that users, and can be done in group also (nosuid – doesn’t allow you to do this)

Some good sizes for partitions (with Solaris)

• Boot – 32 megs
• Swap – 2 times your ram (the system will crash if you run out of swap space!) (swap –s - shows swap space)
• Var – 64 megs – all mailbox’s go here and log files
• Optional software (/opt) – dependent on how much extra software you have
• OS – 256 –350 megs (ver 2.6 takes 396 megs)

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