using sata with sequential file preallocation - the answer
Well I setup a small test bed for this and think I see how it works.
All the seq files are defined to the storage pool and have a initial
size of whatever the dsmfmt used. As tsm needs to use these files, it
deletes one and allocates another and the file grows until it reaches
max size or the partition runs out of space. It then deletes the next
available file on that patition and uses that space until the partition
is full again. Then on to the next file, etc. When it finally runs out
of the available preallocated files it moves on to files in the next
Here is a question for all of you that are using large disk arrays with
stgpools using seq file type.
TSM server v184.108.40.206
We are installing a 6tb sata raid5 array as an intermediate stgpool to
be used with sequential file type. The array will have 3 partitions of
2tb each and all files will have be preallocated because of the devclass
limitation of only using one partition dynamically. The hierarchy will
be local disk --> local attached sata --> tapepool.
Let's say I predefine 1000 files of 1gb each (1tb total out of 2tb
available) in each of the partitions and then set the devclass max
capacity to 20gb. When writing data to the intermediate stgpool TSM will
keep adding files up to 20gb each and up to 1000 files or until the
partition is full at something less than 1000 files.
With mostly 20gb files the partition will fill with about 100 files.
What happens next? Does TSM then use preallocated files in the next
available partition or does it give some sort of allocation error
because it hasn't used the 1000 files but has run out of space in the
I guess another question might be, does TSM do some sort of round robin
use of files on the three partitions or does it use files on one
partition until it is forced to use files on the next partition?
Steve Bennett, (907) 465-5783
State of Alaska, Enterprise Technology Services, Technical Services Section