Re: Mirroring, Striping, Etc.

Michael Whisenant ( )
Sat, 07 Feb 1998 13:01:11 -0600

The best approach would be to change controllers to a RAID controller that
delt with the overhead in hardware, rather than software. NT's software
striping will improve performance as Dale stated. He has tremendous
experience in this manner. However, performing the striping in say a Mylex
or DPT controller will improve performance. Since this is your mail
server, and you seem concerned about reliability, then I would suggest that
you go with a RAID 5 config. Use smaller size hard disks and use more of
them, then use hardware RAID. On my mail server I have 12 2GB hard disks
and Hardware RAID 5, using a Mylex RAID controller with 16MB of cache.
Then I have the 1st logical drive as a 2GB, the remainding ~20GB as the
second logical drive and I can remove any 1 hard drive, while running and
never miss a beat. I use this as a demostration to clients about fault

If you are planning to use this for SQL then use RAID0 and make sure you
have backups. According to many conversations with Dale earlier, the key
again is to distribute the load accross many platters on as many
controllers as possible. I am working on installing SQL server on another
machine that will have 2 of the Mylex dual channel RAID controllers with 9
1GB SCSI drives. Then I will stripe across all platters on 3 of the
controller channels. By adding plenty of RAM, I plan on placing the entire
database in RAM. I want to then have my existing SQL server be a LIVE
backup of the primary. As I understand it that is not currently supported
by Emerald and Dale at this time. I am just getting ready so if Dale needs
a test subject I'll be ready.

At 12:59 AM 2/3/98 -0800, you wrote:
>Gregory White wrote:
>> Can someone offer some information regarding performance
>> improvements/degradation caused by drive mirroring and striping on NT 4?
>> We recently added a second drive to our mail server and set it up as a
>> mirror drive. Since then, it seems to be slower in responding when sending
>> mail. It may just be perception, since I am paying more attention to the
>> machine now.
>> We are running a PP150 w/128 MB Ram and 2- 2.1 GB SCSI on an Adaptec 2940.
>Mirroring will slow the disk access down for writing. Reading
>should be negligible (possibly faster). I tested two wide scsi
>two drives on a Cyrix 166 box w/64mb of memory. With a single drive
>I would sustain 9mb/second reading from a sequential 512mb file and
>and 4mb/sec random. Striping two drives took the performance to
>about about 15 and 6, respectively. So the performance did improve
>with the striping. We do a lot of mirroring with drives for SQL Server
>and production servers for the fault tolerance, and its saved us
>more than once.
>Dale E. Reed Jr. (
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