This is 3 MB/second, which is typical of LTO-1 performance when the drive
is NOT streaming. Switching to LTO-2 technologies should greatly improve
on this restore time. DLT drives have the same issues.
Orville L. Lantto
Datatrend Technologies, Inc. (http://www.datatrend.com)
IBM Premier Business Partner
121 Cheshire Lane, Suite 700
Minnetonka, MN 55305
Email: Orville.Lantto AT datatrend DOT com
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"Coats, Jack" <Jack.Coats AT BANKSTERLING DOT COM>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
01/21/05 05:54 PM
Please respond to
"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
To
ADSM-L AT VM.MARIST DOT EDU
cc
Subject
Re: Why do database restores take so long?
I did a restore of our database last Monday. It took about 5.5 hours
for 60G with nothing else running on the server, with an LTO-1 tape
drive, SCSI attached, to our IBM 3583 library. This is in a Windows2000
environment, but even at that, this is VERY slow. The daily full backup
of the database seems to take the same amount of time.
I would like for the database restore to be faster, but the backup is a
problem too.
I would like to know how to make a database backup to a remote DISK
drive (or a TSM-DR system) and how to restore the database on that
system from that disk drive file! (Pointers to admin docs would be fine!
:) )
-----Original Message-----
From: Tab Trepagnier [mailto:Tab.Trepagnier AT LAITRAM DOT COM]
Sent: Friday, January 21, 2005 5:16 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Why do database restores take so long?
Dave,
Our database disk system consists of four 18 GB SCSI disks in a split
(dual-bus) disk pod connected to a dual-channel LVDS adapter. The
Recovery Log in on another pair of such disks. One set of disks on one
bus holds the primary database and log volumes; two DB and one log disk.
Each DB/log volume is mirrored to an identical volume/disk on the other
bus. So the mirror read/writes occur on independent buses downstream of
the PCI slot. The database consists of four volumes per disk of about 4
GB each. All database and log volumes are defined on JFS2 file systems.
The LVDS adapter is the IBM 64-bit dual-channel adapter called "PCI DUAL
CHANNEL ULTRA3 SCSI ADAPTER", Part Number 09P2544.
The disks are "16 Bit LVD SCSI Disk Drive (18200 MB)", Machine Type and
Model = ST318305LC which I *think* is 15K rpm.
The server is a 2-way 6H1 64-bit 600 MHz with 4 GB RAM, tuned for just
about zero paging. TSM DB buffer pool is 1 GB.
Like I said, when backing up to our HP 4/40 DLT via HVD SCSI, topas
reports a consistent 11 MB/s, such that a typical backup takes just
about
45-50 minutes including the tape mount.
The restore took slightly over three hours; and the 3:1 ratio is not out
of line based on other responses.
Thanks.
Tab
"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> wrote on 01/20/2005
11:27:02 PM:
> Can you provide a little more information? I would like to know:
>
> 1. What kind of disk subsystem are you restoring the data to?
> 2. How many disks, and what kind of disks are they?
> 3. How is the database laid out database volume wise?
> 4. Does the disk have write cache behind it?
> 5. What kind of controller do you have for the disk
subsystem?
>
> At 07:23 PM 1/20/2005 -0600, you wrote:
> >TSM 5.1.9.0 on AIX 5.2 ML4; DLT8000 media on SCSI
> >
> >Why do TSM database restores take so much longer than the backups?
Our
> >system backs up our 24 GB database to DLT in about 50 minutes with a
> >sustained rate of 11 MB/s reported by topas.
> >
> >Tonight I'm performing a database restore. It is occurring at an
average
> >rate of less than 1 MB/s with rare peaks no higher than 6 MBs. At
times
> >the rate is as low as 300 KB/s.
> >
> >I realize the system is writing data to disk rather than reading so
its
> >not doing as much caching, but these are new disks and I've seen them
> >stream write at better than 25 MB/s on the inner edge and as fast as
50
> >MB/s on the outer edge. So I doubt the disk is the problem.
> >
> >This restore has been running for almost 2-1/2 hours now and is about
90%
> >complete.
> >
> >This is the fourth or fifth time I've restored the TSM database in
the
> >seven years I've operated the system. I have never seen database
restores
> >exceed 1/3 the backup rate - sustained - on two different servers,
three
> >different media and going back to ADSM 3.1.
> >
> >Just curious.
> >
> >Tab Trepagnier
> >TSM Administrator
> >Laitram, L.L.C.
>
> Dave Canan
> TSM Performance
> IBM Advanced Technical Support
> ddcanan AT us.ibm DOT com
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