HOW MANY PP'S WOULD BE AVAILABLE WITH THE 2.0GB
ITEM: RTA000035632
QUESTION:
Customer will be adding 2.0GB serial link disk drives to their existing
970/980 and would like to know what's the number of physical partitions
that are available to the user? For eg. they are currently using 1.07GB
drives ( with a PP of 4MB ), and the system makes 255pp/disk available.
Can you provide me some guidance with this calculation please?
I looked at another item (using the search words 2.0Gb & pp) and it
stated that for 7135's the system uses 3% of space for inodes. So, if
this still holds true for the 2.0GB serial link drives, this means
that 1940Mb are available and dividing this by 4Mb, I would have 485pp,
right? Thank you.
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A: The RISC System/6000 System Overview explains that the formatted
capacity of a 2 GB drive is 2013 MB. Of this space, 5 percent is
allotted as overhead for the LVM. The System Overview explains that
the 1.07 GB drive has 1070 MB of formatted capacity. 95 percent of
this divided by 4MB (partition size) gives 254.125 partitions.
Following this algorithm, the 2 GB drive should have 478.0875
partitions (2013x.95/4). As you can see, this gives you a very good
approximation as to how many partitions you will need.
I would like to also explain the 3 percent you had heard referenced.
Within each journaled filesystem, 3 percent of the space available is
used in inode allocation. For example, if you use the entire 2GB disk
referenced above as one filesystem, your filesystem would contain only
1854.980 MB of useable space ((2013x.95)x.97). The 3 percent overhead
for a filesystem is for JFS's only. A raw logical volume, paging
space, or some other device that was not a JFS, would not suffer this
loss.
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This item was created from library item Q645490 CMLJF
Additional search words:
AVAILABILITY AVAILABLE CHAIN CMLJF CONNECT DASD DEC93 DISC DISKETTE
DRIVES HARDWARE IX LINK LINKAGE OZIBM PP PRODUCT PROGRAM RISCOHW
RISCSYSTEM SERIAL SERIALIZE SERIES 2.0GB
WWQA: ITEM: RTA000035632 ITEM: RTA000035632
Dated: 04/1996 Category: RISCOHW
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