IDS Forum

Re: Checkpoint times

Posted By: ART KAGEL, BLOOMBERG/ 731 LEXIN
Date: Monday, 21 May 2007, at 5:15 p.m.

In Response To: Checkpoint times (Marcus Haarmann)

Slow disks? Are you perhaps using RAID5? Singleton disks?

Are the logical and physical logs on the same drive structure as each other? As
your data?

Are you using RAW or COOKED chunks? If COOKED, you do not have nearly enough
AIO VPs configured. You should have ~1.0-1.5 times the number of COOKEID chunks
plus 3-6 for overhead and text logging. If you are using RAW devices for
chunks do you have KAIO enabled in your Solaris kernel? In the IDS instance?

Art S. Kagel

----- Original Message -----
From: Marcus Haarmann <ids@iiug.org>
At: 5/21 17:10:01

Hi,

we encounter enhanced checkpoint times on a production instance.
I have tried to modify some parameters which results in less
checkpoints, but still long (at least for our system).
Actual config is Sun 280R, 4GB Ram, 2 Processors, Solaris 9 (Sparc), IDS
10.00FC6.
Checkpoint interval was set to 60 sec, but this resulted in a (fuzzy,
but blocking!) checkpoint each minute for about 11-21 sec. (which means
the server is not reacting for about 25% of the time).
I have now set checkpoint interval to 900 sec, set buffers to 200000/2k,
lru_max/min is 1.5/1.0.
I have increased physical file size to 100000. Physical buffer is 1024,
LRUS is 32

Now we get (fuzzy, but still blocking, according to onstat output
(BLOCKED: CKPT)) checkpoints for about 20-30 sec, but only at 15 min
intervals.
Maybe the interval is decreasing over the day because of reaching the
dirty percentage, I will check for that tomorrow.
This is better of course, but still I want to know what could be the
reason, I cannot see we write that many data within a minute.
I have read that in 9.40, the recommended action for increased
checkpoints (at least for upgraders of 7.x) is to increase the file size
for logfiles.
Is this still true for 10.0 ? Actual log size is 20000 (one log per hour
normally).

Other useful values:
# Shared Memory Parameters

LOCKS 500000 # Maximum number of locks
NUMAIOVPS 1 # Number of IO vps
PHYSBUFF 1024 # Physical log buffer size (Kbytes)
LOGBUFF 128 # Logical log buffer size (Kbytes)
CLEANERS 32 # Number of buffer cleaner processes
SHMBASE 0x10a000000 # Shared memory base address
SHMVIRTSIZE 500000 # initial virtual shared memory segment
size
SHMADD 50000 # Size of new shared memory segments
(Kbytes)
SHMTOTAL 0 # Total shared memory (Kbytes).
0=>unlimited
CKPTINTVL 900 # Check point interval (in sec)
TXTIMEOUT 0x12c # Transaction timeout (in sec)
STACKSIZE 256 # Stack size (Kbytes)

Any recommendations ?

Thanks in advance,

Marcus

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Messages In This Thread

• Checkpoint times
  Marcus Haarmann -- Monday, 21 May 2007, at 5:09 p.m.
  • Re: Checkpoint times
    ART KAGEL, BLOOMBERG/ 731 LEXIN -- Monday, 21 May 2007, at 5:15 p.m.
    • RE: Re: Checkpoint times
      Marcus Haarmann -- Tuesday, 22 May 2007, at 3:35 a.m.
      • RE: Re: Checkpoint times
        ART KAGEL, BLOOMBERG/ 731 LEXIN -- Tuesday, 22 May 2007, at 7:54 a.m.
  • Re: Checkpoint times
    Keith Simmons -- Tuesday, 22 May 2007, at 3:43 a.m.
    • RE: Re: Checkpoint times
      Marcus Haarmann -- Tuesday, 22 May 2007, at 4:09 a.m.
      • Re: Re: Checkpoint times
        Keith Simmons -- Tuesday, 22 May 2007, at 4:59 a.m.
        • Re: Re: Checkpoint times
          TILMAN MODEL-BOSCH -- Wednesday, 23 May 2007, at 4:19 p.m.
          • Re: Re: Checkpoint times
            ART KAGEL, BLOOMBERG/ 731 LEXIN -- Tuesday, 29 May 2007, at 2:36 p.m.
      • RE: Re: Checkpoint times
        Tilman Model-Bosch -- Wednesday, 23 May 2007, at 4:13 p.m.
        • RE: Re: Checkpoint times
          Robert Roussey\(IT\) -- Wednesday, 23 May 2007, at 4:27 p.m.

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