Re: Virtual tape

Chuck

If you know - is the offline size listed in DSPOBJD that when saved with DTACPR(*YES)? If so, the other options, such as DTACPR(*MEDIUM), can give even better compression that that, from tests I ran a while ago.

Thanks
Vern

-------------- Original message --------------
From: CRPence <CRPbottle@xxxxxxxxx>

Parallel save to tape is available [from BRMS] to spread save
activity across multiple [virtual] tape devices. Two forms of parallel
save are available; one is a serial format for the data [labels] across
the different media devices and the other a parallel format where the
data for the labels is spread across different media devices. Searching
tokens PARALLEL SAVE in InfoCenter returns among others, the following link:
http://publib.boulder.ibm.com/infocenter/iseries/v5r4/topic/rzaiu/rzaiusavinglib
raries.htm

If there is not a matching physical drive for each virtual, only the
serial format is reasonable. Outside of a utility like BRMS, listing
the order of the labels to enable consecutive restore would be prudent,
if fewer physical devices might be available than the number of virtual
devices used for the save.

As for storage, the virtual tape device provides no data compaction
because there is no hardware, but the Data Compression DTACPR()
parameter enables software compression which can make the saved library
or object significantly smaller [in its offline size] than its online
size, but at the cost of the CPU to effect that compression. The
offline size for an object is presented in DSPOBJD output. Other than
the ability to save multiple libraries on a virtual tape versus only one
on library into a save file, because the compression is in software,
there should be little difference between the two. See the DTACPR
parameter on SAVLIB for example:
http://publib.boulder.ibm.com/infocenter/iseries/v5r4/topic/cl/savlib.htm

Regards, Chuck