ADSM-L

Backup performance

2001-02-23 04:47:27
Subject: Backup performance
From: Valeriano Bassi <Valeriano.Bassi AT SSB DOT IT>
Date: Fri, 23 Feb 2001 10:40:31 +0100
Hi there,
first of all sorry for the long append but I need to explain my problem in
detail.
I was trying to optimize our backup performance for a particular node, so I got
a look at
INSTR_CLIENT_DETAIL trace output.

Server is ADSM 3.1.2.50 on OS/390 V2R6
Client is USS 3.1.0.5
Commethod is TCPIP using a CTC (Channel To Channel) connection
Client and Server are on two separate LPAR on the same 2064 machine

Here is our starting point:
Total number of objects inspected:   52,041

Total number of objects backed up:    1,554

Total number of objects updated:          0

Total number of objects rebound:          0

Total number of objects deleted:         72

Total number of objects failed:           0

Total number of bytes transferred:     8.10 GB

Data transfer time:                  256.23 sec

Network data transfer rate:        33,168.89 KB/sec

Aggregate data transfer rate:      1,396.01 KB/sec

Objects compressed by:                   55%
Elapsed processing time:           01:41:28

and trace output:

Elapsed time:  6088.402 sec

Section      Total Time(sec)  Average Time(msec)  Frequency used

-----------------------------------------------------------------
Client Setup        0.063           62.9              1
Client Setup        0.063           62.9              1
Process Dirs      108.029           47.1           2292
Solve Tree          0.000            0.0              0
Compute             2.003            0.0         768476
Transaction        46.226            0.0        2312991
BeginTxn Verb       0.007            0.0           1181
File I/O         2659.223            4.6         580646
Compression      2964.974            4.3         692721
Data Verb         255.722            1.0         266454
Confirm Verb        0.202            4.9             41
EndTxn Verb        51.560           43.7           1181
Client Cleanup      0.392          392.2              1

So,according to common tuning consideration, I decide to turn client compression
 off.
The results weer not as expected:

Total number of objects inspected:   57,067

Total number of objects backed up:    1,450

Total number of objects updated:          0

Total number of objects rebound:          0

Total number of objects deleted:        507

Total number of objects failed:           1

Total number of bytes transferred:    18.53 GB

Data transfer time:                6,941.87 sec

Network data transfer rate:        2,799.28 KB/sec

Aggregate data transfer rate:      1,858.10 KB/sec

Objects compressed by:                    0%
Elapsed processing time:           02:54:18

and trace output:

Elapsed time: 10458.494 sec

Section      Total Time(sec)  Average Time(msec)  Frequency used

------------------------------------------------------------------
Client Setup        0.766          765.9              1
Client Setup        0.766          765.9              1
Process Dirs      123.954           47.2           2625
Solve Tree          0.000            0.0              0
Compute             1.975            0.0         608333
Transaction        53.118            0.0        1831471
BeginTxn Verb       0.009            0.0           1179
File I/O         3239.495            5.3         609776
Compression         0.000            0.0              0
Data Verb        6940.654           11.4         608333
Confirm Verb       38.818          825.9             47
EndTxn Verb        59.321           50.3           1179
Client Cleanup      0.385          384.6              1

My question is; why Data Verb is so increased while data to be transferred are
only doubled?
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