ssa really slow, is this normal?

ssa really slow, is this normal?

Post by l.. » Thu, 13 Jan 2000 04:00:00



hello,

  i have 24 9.1gb ssa disks attached to an 7025-F50 server with a SSA-Raid-5
  pci adapter running aix 4.3.3.1.  i built a file system spanning 19 of these
  disks.  the file system is not mirrored, striped or raid.  i have a program
  to write files of large sizes (greater than 10 gigabytes).

  while this program is writing to the ssa file system, if i access this
  file system with commands like: cat, ls, df, du, ..., they can take
  anywhere from 30 seconds to 2 minutes to complete.

  is this normal for ssa disk?

  for comparison, if i run this program on scsi disk devices there is no
  significant delay between issuing the commands and their completion.

tia

lloyd

LLOYD M CALDWELL
UNIVERSITY OF UTAH
CTR FOR HIGH PERFORM COMPUTING
155 SOUTH 1452 EAST RM 405
SALT LAKE CITY UT  84112-0190


 
 
 

ssa really slow, is this normal?

Post by Simon Marches » Sat, 15 Jan 2000 04:00:00



> hello,

>   i have 24 9.1gb ssa disks attached to an 7025-F50 server with a SSA-Raid-5
>   pci adapter running aix 4.3.3.1.  i built a file system spanning 19 of these
>   disks.  the file system is not mirrored, striped or raid.  i have a program
>   to write files of large sizes (greater than 10 gigabytes).

>   while this program is writing to the ssa file system, if i access this
>   file system with commands like: cat, ls, df, du, ..., they can take
>   anywhere from 30 seconds to 2 minutes to complete.

>   is this normal for ssa disk?

>   for comparison, if i run this program on scsi disk devices there is no
>   significant delay between issuing the commands and their completion.

> tia

> lloyd

> LLOYD M CALDWELL
> UNIVERSITY OF UTAH
> CTR FOR HIGH PERFORM COMPUTING
> 155 SOUTH 1452 EAST RM 405
> SALT LAKE CITY UT  84112-0190



But does the SCSI config execute the write program faster or slower than
SSA?
--
comp.unix.aix FAQ:
http://www.faqs.org/faqs/by-newsgroup/comp/comp.unix.aix.html

 
 
 

ssa really slow, is this normal?

Post by ka.. » Thu, 20 Jan 2000 04:00:00



> hello,
>   i have 24 9.1gb ssa disks attached to an 7025-F50 server with a SSA-Raid-5
>   pci adapter running aix 4.3.3.1.  i built a file system spanning 19 of these
>   disks.  the file system is not mirrored, striped or raid.  i have a program
>   to write files of large sizes (greater than 10 gigabytes).
>   while this program is writing to the ssa file system, if i access this
>   file system with commands like: cat, ls, df, du, ..., they can take
>   anywhere from 30 seconds to 2 minutes to complete.
>   is this normal for ssa disk?
>   for comparison, if i run this program on scsi disk devices there is no
>   significant delay between issuing the commands and their completion.
> tia
> lloyd
> LLOYD M CALDWELL
> UNIVERSITY OF UTAH
> CTR FOR HIGH PERFORM COMPUTING
> 155 SOUTH 1452 EAST RM 405
> SALT LAKE CITY UT  84112-0190


Check OS' High/Low water mark of write-behind cache.
(under 'Change / Show Characteristics of Operating System' in smit)
If water marks are 0, change to appropriate value(32/24 for each.. in my
case).
 
 
 

1. Really, really slow connection to local server via PPP.

Well, this is puzzling--

I've been scratching my head over this for months, reading docs, looking
for non-existent IRQ conflicts because I *thought* I had a problem with
my PCMCIA and/or PPP setup. Just realized that the problem is specific
to *one server*--which happens to be the one I access the most.

* the problem server is in my local domain. It's the one where I have a
shell account (which I often use--or try to use--to ftp stuff back and
forth between home & office), and it's also the primary DNS and the mail
server for the domain.

* the server is an AIX machine which seems up to its job (it's only gone
down once in my 2 years here). When I access it from my office via an
ethernet connection, everything works fine. I can download a multi-meg
file in seconds.

* when I access the net through my PPP connection from home (using a
28.8k PCMCIA modem, dynamic IP addressing), I get reasonable speeds for
http & ftp servers outside the local domain . . . well, slow, but
consistent with what I get in the office.

* when I access this one local server, FTP is mind-numbingly slow (<100
bytes/second!) and I often can't complete a large transfer. Similarly,
if I try to get my mail, it's very slow and tends to stall if there are
a lot of messages.

Any ideas what's causing this? Thanks for any info.

Matt Gushee
Oshamanbe, Hokkaido, Japan

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