Re: Realistic drive arrays

Thanks again, I am going to push for the 6th drive and use 3 mirrors. There 
may be an opportunity to swap 2 of the disks for a pair of 143Gb drives from 
another server. To reduce the tendancy of the databases to grow I am going to 
instigate mailbox restrictions and look at mail archiving outside of the 
Exchange system to allow me to force users to maintain their mailboxes 
properly. This also reduces the need for most users to have large personal 
folders.

I am a bit cautious as my current 2k system has a 14Gb database set despite 
the use of pst files, one user has overfilled 3 already.

"John Fullbright" wrote:

> Another option in DR situations is a USB drive on hand.  I's rather use a 
> USB drive than redirect to a share.  A local drive is alway optimal.
> 
> RAID 5 with three disks is really a bad choice.  Write performance is 85*2/4 
> or 42.5 IOPS.  Read performance is 85*2 = 170 IOPS.  For a mixed load with a 
> 2:1 R/W ratio, 126.225 IOPS.  If you go with RAID 5, you need a lot of 
> spindles to get the write performance up to an acceptable level.  You get 
> the same performance with far fewer spindles with RAID 1/10/0+1.  A mirror 
> is 100% redundant.  Without a hotspare, you would have to weigh the risk of 
> two drives in the same mirror failing within the parts replacement SLA of 
> your hardware vendor.  In practice, the chance of this happening in say an 8 
> hour window is very remote. Of course, the longer you wait to replace a 
> failed drive the higher the probability of a second failure occurring will 
> become.  What about ordering an extra drive and having a spare on the shelf? 
> I'd recommend an analysis of your risk mitigation options.
> 
> How much memory the store.exe process uses really depends on how much memory 
> you have installed.  Store, of course, isn't the only exchange process that 
> uses memory.  With the /3gb switch, each user mode process can have an 
> address space of up to 3GB.  Inetinfo, where smtp lives, consumes memory, as 
> well as other exchange processes.  Then there's Anti-virus, backups, and any 
> other process running on the server.  It's hard to say how much memory will 
> be used without very specific information on what's loaded and what the load 
> is.  It's easier just to measure with perfmon.
> 
> 
> 
> 
> 
> 
> "Missing Link" <MissingLink@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message 
> news:233D83F4-3C19-45E1-B82E-36EAB7602573@xxxxxxxxxxxxxxxx
> > Thanks for that, a triple mirror set was one of my considerations
> > particularly on the servers I have specified. One of the problems I have 
> > is
> > that two of the servers only have 5 36Gb drives. I didn't specify these 
> > ones
> > myself and I can get a 6th drive in to do the triple mirror setup but I am
> > concerned about only 36Gb in a DR situation where I may need more than one
> > copy of the database on the disk. As an alternative I was going to mirror 
> > 1
> > pair for the logs, raid 5 with partitions using 3 disks for the rest which
> > gives some redundancy then define the 6th drive as a hot swap spare for 
> > both
> > arrays. I know this does not give me the performance of a mirror but does
> > increase the contiguous disk space available, given the number of users 
> > and
> > that few of them are heavy mail users performance should not be an issue.
> > With adequate memory how much does Exchange make use of the swap file?
> > I would rate the I/O capability of this as of equal to the logs.
> >
> > "John Fullbright" wrote:
> >
> >> Three mirrors, excellent answer.  I would add, you could create 
> >> additional
> >> partitions on Physical disk 0 for the bulk of your page file, and the 
> >> system
> >> temp director and smtp queues.  This doesn't do anything for IO load, but
> >> does help reduce fragmentation.
> >>
> >>
> >> "Hobdey" <Hobdey@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> >> news:ACA9B76B-7DAC-4148-8575-4F82D324F07A@xxxxxxxxxxxxxxxx
> >> > Personally with the 6 drives in question, I would run 3 mirrored sets: 
> >> > 1
> >> > for
> >> > the OS and Exchange executables (also leaving the default SMTP 
> >> > directories
> >> > on
> >> > this set), 1 for the data stores (EDB and STM files), and 1 for the
> >> > database
> >> > log files.
> >> >
> >> > Even if you don't go that way, make certain you mirror your OS 
> >> > partition
> >> > because even though there's not much activity there, a disk loss would 
> >> > be
> >> > a
> >> > serious pain to recover from.  Plus, as I alluded to, the default 
> >> > location
> >> > for the SMTP queue directories is on that partition as well and there's 
> >> > a
> >> > fair amount of activity there.  I wouldn't do anything with RAID 5 in 
> >> > your
> >> > situation because you don't have the disks to spare.
> >> >
> >> > "Missing Link" wrote:
> >> >
> >> >> I am looking for documents giving realistic recommendations for drive
> >> >> array
> >> >> configurations for exchange server 2003 for and organisation with a
> >> >> maximum
> >> >> of 150 users per server in a distributed network Many that I have 
> >> >> found
> >> >> give
> >> >> proposals that require at least 8 drives, one if you followed it 
> >> >> through
> >> >> wanted 22!!
> >> >>
> >> >> Both Dell and HP sell servers that have 6 drives, what is the best way 
> >> >> to
> >> >> split these up for a mailbox server. The "Tuning Exchange Server 2003
> >> >> Performance" chapter refers to an smtp bridgehead as using one 
> >> >> partition
> >> >> with
> >> >> mirroring if available. I would have split the single array drive into 
> >> >> a
> >> >> number of partitions if only to reduce fragmentation, what does anyone
> >> >> else
> >> >> think. Is there any real benefit using a mirror for the O/S over a 
> >> >> raid 5
> >> >> array as once it us loaded there should be little O/S activity in
> >> >> comparison.
> >> >>
> >> >> Alan
> >>
> >>
> >> 
> 
> 
> 
.

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