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Dr. is probably correct here. Can the disk arms swing stuff into memory as fast as 2844 and 280D can punch memory to fibre and as fast as LTO4 can lay it on tape? What's the latency as disk controller lays a page in memory before tape controller can read it off and free it up for another disk I/O? IBMi is probably doing a pretty good job pre-fetching and utilizing multiple processors to interleave disk reads. Tape I/O is still very single threaded.

-----Original Message-----
From: DrFranken [mailto:midrange@xxxxxxxxxxxx]
Sent: Thursday, June 13, 2013 3:26 PM
To: Midrange Systems Technical Discussion
Cc: Dan Kimmel
Subject: Re: LTO4 vs LTO3 speed

It's ALL about the I/O here.

How many disk arms are playing here?

Are said arms virtual or Physical?

If virtual what's the host partition?

Do they live on internal disk or SAN?

Mirrored or RAID or (shudder) neither?

What are the arms? (10K, 15K, SAS, SCSI, SSD?)

And also how much memory on the partition in kwestion?

- Larry "DrFranken" Bolhuis

www.frankeni.com
www.iDevCloud.com
www.iInTheCloud.com

On 6/13/2013 4:11 PM, Dan Kimmel wrote:

At this point we have to look to the systems guys. Larry, Jim, Pete? Could be either the 2844 or the 280D or the stuff that connects them. Could also be something completely off the box (switches, tape drive internals, ???).

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of rob@xxxxxxxxx
Sent: Thursday, June 13, 2013 3:02 PM
To: Midrange Systems Technical Discussion
Subject: RE: LTO4 vs LTO3 speed

WRKHDWRSC *STG

Resource Type-model Status Text
CMB04 2844-001 Operational Storage Controller
DC05 280D-001 Operational Tape Controller
TAPGRT01 3573-040 Operational Tape Library


2844 Location : U0595.001.10782A9-CB1-C03
280D Location : U0595.001.10782A9-CB1-C04


Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1 Group Dekko Dept 1600 Mail to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





From: Dan Kimmel <dkimmel@xxxxxxxxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>,
Date: 06/13/2013 03:56 PM
Subject: RE: LTO4 vs LTO3 speed
Sent by: midrange-l-bounces@xxxxxxxxxxxx



I doubt if it's CPU. At least not main CPU. There's a lot of plumbing
between the main CPU and I/O devices. The CPU probably loads a block
into memory, then passes the address to I/O controller processor which
copies memory to the I/O port and handles protocol. So you're
dependent on the speed of that I/O processor and all the channels and
busses that connect it to memory and to the I/O port.

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [
mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of rob@xxxxxxxxx
Sent: Thursday, June 13, 2013 2:51 PM
To: Midrange Systems Technical Discussion
Subject: RE: LTO4 vs LTO3 speed

Perhaps the CPU? Perhaps a Power 6 9117-MMA P30 just ain't man enough
to drive this bad boy?

Resource Type-model Status Text
CEC01 9117-MMA Operational Main Card Enclosure
PN03 28D4 Operational System Control Panel
MP13 53CF Operational System Processor Card
MP14 53CF Operational System Processor Card
MP15 53CF Operational System Processor Card
MP16 53CF Operational System Processor Card
MP17 53CF Operational System Processor Card
MP18 53CF Operational System Processor Card
MP19 53CF Operational System Processor Card
MP20 53CF Operational System Processor Card
PV01 52AD Operational Processor Capacity Card
SP04 294E Operational Service Processor Card
SP05 294E Operational Service Processor Card
...



Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1 Group Dekko Dept 1600
Mail
to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





From: Dan Kimmel <dkimmel@xxxxxxxxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>,
Date: 06/13/2013 03:42 PM
Subject: RE: LTO4 vs LTO3 speed
Sent by: midrange-l-bounces@xxxxxxxxxxxx



Not much difference. Leads me to believe (or suspect, anyway) your
performance bottleneck is not the speed of the tape, drive, or
connection media.

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [
mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of rob@xxxxxxxxx
Sent: Thursday, June 13, 2013 2:23 PM
To: midrange-l@xxxxxxxxxxxx
Subject: LTO4 vs LTO3 speed

I read a chart that says basically:
LTO1: Up to 40MB/s
LTO2: Up to 80MB/s
LTO3: Up to 160MB/s
LTO4: Up to 240MB/s
LTO5: Up to 360MB/s
LTO6: Up to 540MB/s
http://www-304.ibm.com/services/weblectures/dlv/partnerworld/online/lt
u29864/mod%208%20ibm%20system%20storage%20tape%20part%203.ppt



And another chart that says the drive makes no difference - it's
totally dependent on the interface (we use 280D or 5774) (something
smells rotten

about this claim).
http://www-01.ibm.com/support/docview.wss?uid=nas1b69de8ff8246ff2c8625
688700566393



This chart says LTO4 Sustained data transfer rate* Up to 240 Mbps
compressed*; 120 Mbps native
http://www-03.ibm.com/systems/storage/tape/oem/lto4/specifications.htm
l Another chart says LTO3 Sustained data transfer rate1: Up to 60
Mbps native

We have the LTO4 drives in question mounted in a 3573-L4U (aka TS3200)
http://www-03.ibm.com/systems/storage/tape/ts3200/index.html

Moved from scsi LTO3 to fiber LTO4.

Full system save completed with BRMS:
03/06/13 06/05/13
LTO3 LTO4
SAVSYS 00:07 00:07
*IBM 00:06 00:05
*ALLUSR 06:06 06:18
*LINK 00:20 00:19
Another system:
LTO3 LTO4
SAVSYS 00:18 00:19
*IBM 00:09 00:08
*ALLUSR 02:28 02:34
*LINK 01:30 01:23
Granted, there was a three month time difference in between there.
Utilization may have changed.
System 1:
Information collected . . . . . . . . . : 04/11/13 04:00:02
% of Size in
Description Disk 1,000,000 bytes
User libraries 77.11 3604127.46
User directories 1.50 70014.59
Folders and documents .00 .14
QSYS .10 4481.52
Other IBM libraries .39 18235.97
Licensed Internal Code .11 5182.31
Temporary space .39 18319.04
Unused space 20.41 953978.86
System internal objects .16 7509.85
Objects not in a library .00 .00
TOTAL 100.17 4681849.74
Information collected . . . . . . . . . : 06/13/13 04:00:02
% of Size in
Description Disk 1,000,000 bytes
User libraries 80.05 3741731.66
User directories 1.56 72747.25
Folders and documents .00 .14
QSYS .10 4596.45
Other IBM libraries .38 17809.87
Licensed Internal Code .11 5199.08
Temporary space .31 14563.16
Unused space 17.57 821259.54
System internal objects .20 9196.28
Objects not in a library .00 .00
TOTAL 100.28 4687103.43
System 2:
Information collected . . . . . . . . . : 04/11/13 04:00:04
% of Size in
Description Disk 1,000,000 bytes
User libraries 71.73 650784.59
User directories 7.37 66912.19
Folders and documents .00 16.75
QSYS .53 4825.70
Other IBM libraries 1.67 15128.99
Licensed Internal Code .54 4913.39
Temporary space 2.45 22214.63
Unused space 14.51 131641.09
System internal objects .98 8872.16
Objects not in a library .00 .01
TOTAL 99.78 905309.50
Information collected . . . . . . . . . : 05/30/13 04:00:08
% of Size in
Description Disk 1,000,000 bytes
User libraries 70.35 638249.19
User directories 7.36 66821.73
Folders and documents .00 16.75
QSYS .77 6973.45
Other IBM libraries 1.90 17223.31
Licensed Internal Code .54 4913.39
Temporary space 2.49 22568.05
Unused space 15.78 143215.09
System internal objects 1.02 9224.12
Objects not in a library .00 .00
TOTAL 100.21 909205.08



Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1 Group Dekko Dept 1600
Mail
to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com

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