Aligning Solaris x86 partitions / slices
2010/09/10 1 COMMENT
Most physical and virtual hardware is now presenting 63 sectors per track. [eg VMware, VirtualBox].
With the advent of “Green” disks with native 4kB blocks, I am increasingly worried about alignment. For Solaris, this needs to happen at two levels – The alignment of the Solaris MBR partition, and the alignment of Solaris slices within that Solaris MBR partition.
In part one of this blog, I will demo how to get around this.
Boot Schillix, or any other Operating System installer
Log in as root, and once at the root prompt, proceed as follows.
Print out the “geometry” of the disk. Here you can see in Cylinder/Head/Sector (CHS) terms, this disk is 2088/255/63
root@unknown:~# fdisk -G c0d0p0
* Physical geometry for device /dev/rdsk/c0d0p0
* PCYL NCYL ACYL BCYL NHEAD NSECT SECSIZ
2088 2088 0 0 255 63 512
You can show the partition table with the following command:
root@unknown:~# fdisk -W - c0d0p0 | tail -5
* Id Act Bhead Bsect Bcyl Ehead Esect Ecyl Rsect Numsect
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
You can see the default “Solaris” partition (type 191 == 0xBF), and geometry that gets created. From this you can see that the first partition starts 16065 sectors in (and therefore not 4kB block aligned).
It’s interesting that this partition doesn’t start 63 sectors in (ie the first sector after the first track). By default, Solaris seems to create the first partition after the entire first cylinder.
root@unknown:~# fdisk -B c0d0p0 root@unknown:~# fdisk -W - c0d0p0 | tail -5 * Id Act Bhead Bsect Bcyl Ehead Esect Ecyl Rsect Numsect 191 128 0 1 1 254 63 1023 16065 33527655 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Ok, let’s wipe that out and start afresh:
root@unknown:~# dd if=/dev/zero count=1 of=/dev/rdsk/c0d0p0
1+0 records in
1+0 records out
Fixing it
Now let’s do things manually. Manually creating the partition 64 sectors in:
root@unknown:~# fdisk -A 191:128:0:0:0:0:0:0:64:33543720 c0d0p0
root@unknown:~# fdisk -W - c0d0p0 | tail -5
* Id Act Bhead Bsect Bcyl Ehead Esect Ecyl Rsect Numsect
191 128 1 2 0 254 63 1023 64 33543720
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
So the partition is now aligned, but we also need to make sure that Solaris slices within the partition are also aligned. I think the easiest way of doing this is to lie to Solaris, and get it to change the virtual geometry from 63 sectors per track to 32 sectors per track. We will need to recalculate the number of sectors, based on the total LBA sectors of the disk. From the calculations below, you can see that the number of tracks should now be 4110, and that the new geometry will fit within the “actual” geometry. [The last thing that we want is to have Solaris try to read past the end of the disk].
root@unknown:~# echo $((2088*63/32)) 4110 root@unknown:~# echo $((2088*255*63)) 33543720 root@unknown:~# echo $((4110*255*32)) 33537600
Ok, now we can create the Solaris VTOC table:
root@unknown:~# format c0d0p0 Failed to inquiry this logical diskselecting c0d0p0 Controller working list found [disk formatted, defect list found] FORMAT MENU: disk - select a disk type - select (define) a disk type partition - select (define) a partition table current - describe the current disk format - format and analyze the disk fdisk - run the fdisk program repair - repair a defective sector show - translate a disk address label - write label to the disk analyze - surface analysis defect - defect list management backup - search for backup labels verify - read and display labels save - save new disk/partition definitions volname - set 8-character volume name !<cmd> - execute <cmd>, then return quit format> curr Current Disk = c0d0 < cyl 2086 alt 2 hd 255 sec 63> /pci@0,0/pci-ide@1,1/ide@0/cmdk@0,0
And here’s where we lie to Solaris, and change the sectors per track to 32:
format> type AVAILABLE DRIVE TYPES: 0. 1. other Specify disk type (enter its number)[0]: 1 Enter number of data cylinders: 4108 Enter number of alternate cylinders[2]: Enter number of physical cylinders[4110]: Enter number of heads: 255 Enter number of data sectors/track: 32 Enter rpm of drive[3600]: Enter format time[default]: Enter cylinder skew[default]: Enter track skew[default]: Enter tracks per zone[default]: Enter alternate tracks[default]: Enter alternate sectors[default]: Enter cache control[default]: Enter prefetch threshold[default]: Enter minimum prefetch[default]: Enter maximum prefetch[default]: Enter disk type name (remember quotes): original selecting c0d0 No current partition list No defect list found [disk formatted, no defect list found] format> curr Current Disk = c0d0 <original cyl 4108 alt 2 hd 255 sec 32> /pci@0,0/pci-ide@1,1/ide@0/cmdk@0,0 format> p PARTITION MENU: 0 - change `0' partition 1 - change `1' partition 2 - change `2' partition 3 - change `3' partition 4 - change `4' partition 5 - change `5' partition 6 - change `6' partition 7 - change `7' partition select - select a predefined table modify - modify a predefined partition table name - name the current table print - display the current table label - write partition map and label to the disk !<cmd> - execute <cmd>, then return quit
And here’s where we create the slices. For the purposes of demonstration, we will create 3 slices : /, swap and /home:
partition> p Current partition table (original): Total disk cylinders available: 4108 + 2 (reserved cylinders) Part Tag Flag Cylinders Size Blocks 0 root wm 3 - 35 131.48MB (33/0/0) 269280 1 swap wu 36 - 68 131.48MB (33/0/0) 269280 2 backup wu 0 - 4109 15.99GB (4110/0/0) 33537600 3 unassigned wm 0 0 (0/0/0) 0 4 unassigned wm 0 0 (0/0/0) 0 5 unassigned wm 0 0 (0/0/0) 0 6 usr wm 69 - 4107 15.72GB (4039/0/0) 32958240 7 unassigned wm 0 0 (0/0/0) 0 8 boot wu 0 - 0 3.98MB (1/0/0) 8160 9 alternates wm 1 - 2 7.97MB (2/0/0) 16320 partition> 0 Part Tag Flag Cylinders Size Blocks 0 root wm 3 - 35 131.48MB (33/0/0) 269280 Enter partition id tag[root]: Enter partition permission flags[wm]: Enter new starting cyl[3]: Enter partition size[269280b, 33c, 35e, 131.48mb, 0.13gb]: 10g partition> 1 Part Tag Flag Cylinders Size Blocks 1 swap wu 36 - 68 131.48MB (33/0/0) 269280 Enter partition id tag[swap]: Enter partition permission flags[wu]: Enter new starting cyl[36]: 2574 Enter partition size[269280b, 33c, 2606e, 131.48mb, 0.13gb]: 2g partition> 6 Part Tag Flag Cylinders Size Blocks 6 usr wm 69 - 4107 15.72GB (4039/0/0) 32958240 Enter partition id tag[usr]: home Enter partition permission flags[wm]: Enter new starting cyl[69]: 3089 Enter partition size[8315040b, 1019c, 4107e, 4060.08mb, 3.96gb]:
This is the final Solaris partition table:
partition> p Current partition table (unnamed): Total disk cylinders available: 4108 + 2 (reserved cylinders) Part Tag Flag Cylinders Size Blocks 0 root wm 3 - 2573 10.00GB (2571/0/0) 20979360 1 swap wu 2574 - 3088 2.00GB (515/0/0) 4202400 2 backup wu 0 - 4109 15.99GB (4110/0/0) 33537600 3 unassigned wm 0 0 (0/0/0) 0 4 unassigned wm 0 0 (0/0/0) 0 5 unassigned wm 0 0 (0/0/0) 0 6 home wm 3089 - 4107 3.96GB (1019/0/0) 8315040 7 unassigned wm 0 0 (0/0/0) 0 8 boot wu 0 - 0 3.98MB (1/0/0) 8160 9 alternates wm 1 - 2 7.97MB (2/0/0) 16320 partition> label Ready to label disk, continue? y partition> q FORMAT MENU: disk - select a disk type - select (define) a disk type partition - select (define) a partition table current - describe the current disk format - format and analyze the disk fdisk - run the fdisk program repair - repair a defective sector show - translate a disk address label - write label to the disk analyze - surface analysis defect - defect list management backup - search for backup labels verify - read and display labels save - save new disk/partition definitions volname - set 8-character volume name !<cmd> - execute <cmd>, then return quit format> q
轉貼自:https://osdude.wordpress.com/2010/09/10/aligning-solaris-x86-partitions-slices/ 
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