Restore problem: speed drops after 50 gigs

[Bartacus]

Hi All,



We're having some recovery problems on a D.R. server. Vital stats as follows:



TSM Server: MVS 5.2.6

TSM Client: Windows 5.1.5



I know its an old client, but restores have not been a problem in the past. The problem: during the restore of very large files, the restore speed starts to die after 50 gigs have been sent. The restore FLIES up to that point, transferring at around 13,000KB/sec (this is fast for us considering the hardware). But after around 50gigs, the speed begins to drop steadily. We've had our LAN guys do a sniffer trace on the LAN connections, and we've found the client is send a "window size 0" message, meaning the client cannot handle the amount of incoming data and its throttling the speed down.



My question: what would cause this? We've done this successfully before, twice, transferring a 300+ gig file without issues, and the speed was consistent the entire time. Now it sucks and we don't know why. TSM hasn't changed, LAN hasn't changed, TSM server hasn't changed, etc. We've installed the 5.1.5 client on a similar Windows server on the same LAN segment, and we don't see this issue, so it appears to be something specific to this client. We also tried removing/reinstalling 5.1.5, but the problem persists. We see no errors, collisions, etc, just a slowdown in transfer speed after 505gigs is transferred. Any idea what would cause this?



Bart

 

[rscherrer47]

Bart,



This might help:



DSMMAXSG (Increasing the Block Size for Writing Data) Running this utility increases the maximum transfer length for Host Bus Adapters (HBAs) and, consequently, the block size used by the Tivoli Storage Manager server for writing data to and getting data from certain types of tape drives. With this utility, the maximum supported block size is 256 KB. Depending on your system environment, the increase in block size could improve the rate at which Tivoli Storage Manager processes data for backups and restores and for archives and retrieves. Note, however, that the utility does not affect the generation of backup sets. The only supported tape drives are those that are attached to SCSI or Fibre

Channel HBAs and that have the following device types: v 3570 v 3590 v 3592 v DLT v DTF v ECARTRIDGE v LTO



:-o

Normally, the utility is executed automatically as part of the Tivoli Storage Manager server and storage agent installation. However, if you install a new HBA on your system after server or storage agent installation or if you install a new version of an existing HBA device driver that resets the value of the maximum transfer size, you must run the utility manually in order to take advantage of the larger block size.