Hugh,
it is not a matter of redundancy rather than Disk IO bottlenecks. Any CRUD
operation will have to write that information to the transaction log as
well. It becomes an issue of SQL server trying to use the same resource for
two separate operations. The preferred method of setup for SQL server for
myself is to have the data and transaction log on, not only different
arrays, but on two separate SCSI channels all together. This is most
instances will rid you of ever having a bottleneck at the Disk IO level.
-----Original Message-----
From: Hugh du Toit
[mailto:mssqldba-ezmlmshield-x33820009.[Email address protected]
Sent: Thursday, May 27, 2004 10:15 PM
To: LazyDBA.com Discussion
Subject: RE: performance thresholds[Scanned]
Hi,
Stupid question here - I've read on different sites and in this forum that
one should store your logs and data files on different drive arrays. I
agree, but if I have a SCSI array, and both files are on the array, isn't
that good enough? The point of putting them on different drives is to save
at least one file should the other crash. But if they are in an array, it
should be a problem, should it? Odds are not all the drives in the array
will crash at the same time...
Regards
Hugh
-----Original Message-----
From: Holland Stephen [mailto:mssqldba-ezmlmshield-x94949958.[Email
address protected]
Sent: Thursday, May 27, 2004 20:07 PM
To: LazyDBA.com Discussion
Subject: RE: performance thresholds[Scanned]
If you have a lot of inserts, deletes, etc., you should not use RAID-5
because of the parity that must be created for the new data entries.
RAID-5 is good for static data, only.
RAID 10 is optimum for both.
And yes, the logs and data should most definitely be on PHYSICALLY
separate media. No virtual drives, partitions, etc.
-----Original Message-----
From: mdefnet
[mailto:mssqldba-ezmlmshield-x20583642.[Email address protected]
Sent: Thursday, May 27, 2004 12:59 PM
To: LazyDBA.com Discussion
Subject: performance thresholds
We are running a SQL Server that is generally running at an average of
50%
CPU utilization and that has me somewhat concerned. It will sometimes
crater to 10-15% (and lower) and sometimes swells to 80% (sometimes even
more, but generally not). It generally follows a sine wave pattern
between
30 and 70%. It is running on a Compaq DL380G3 running W2K3 Enterprise
Edition, SQL Server 2000 SP3a, 6GB of memory, SQL Server itself is
installed
on drive C:, the two user databases and logs share drive D: which is
RAID-5
on 4x146GB drives, and 2 physical 3.08GHz CPUs (that appear as four to
the
OS and SQL Server ... I was told the two virtual CPUs are the same as
physical ones). It never does memory pages, and the avg. disk queue
length
is almost always under 1. The databases are both about 10GB in size
with
5GB of logs each so there is a lot of open disk space.
Does the CPU utilization sound too high? I don't know what comprises a
reasonable threshold for a SQL Server-based server. The primary reason
I am
asking is that the developers are stating they are getting frequent
timeouts. Should the log files be put on a separate drive array? I've
read
that the log files should be physically separated from the data files
and
the recommendation is RAID-5 for the DB and RAID-10 for the logs. Is
this
overkill?
Any thoughts or recommendations are greatly appreciated. Or am I
concerned
for no reason?
Mike
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