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Disk config for Exchange and DB server on VMWare

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For a client we have to set up several servers in a VMWare environment. Storage will be on a SAN with 12 disk capacity. Number of users is +/- 70. The servers that will run on it are:

- Windows 2008 Domain Controller (x64) + file/print

- Windows 2008 Domain Controller (x64) + Exchange 2007

- 1 to 3 Windows 2003 (x86) member servers for database apps. We'd like to consolidate this into 1 server as the apps all use Progress but the different vendors will probably ask each their own server.

- Some less resource intensive things like an ftp server and web proxy will also run on this SAN until they are replaced by other solutions

The idea was to use 6 10k or 15k disks for file storage (RAID 5 or 6) and 6 300 GB 15k disks for database and Exchange (RAID 10). The file storage stuff is ok but we're not sure whether it would be best to use a single 6 disk RAID 10 (900 GB)with several LUNs for Exchange or a 4 disk RAID 10 (600 GB) for Exchange and a mirror (300 GB) for the databases to separate them completely. Or a 4 disk RAID 10 with 450 GB disks giving us the same capacity but room for growth. My colleague who's in charge wants this done right - both Exchange and the databases have to be FAST and have room for growth and there has to be room for snapshots - hence the number, speed and capacity of disks. I'm really not sure what kind of disk config we should best run on this.

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For a client we have to set up several servers in a VMWare environment. Storage will be on a SAN with 12 disk capacity. Number of users is +/- 70. The servers that will run on it are:

- Windows 2008 Domain Controller (x64) + file/print

- Windows 2008 Domain Controller (x64) + Exchange 2007

- 1 to 3 Windows 2003 (x86) member servers for database apps. We'd like to consolidate this into 1 server as the apps all use Progress but the different vendors will probably ask each their own server.

- Some less resource intensive things like an ftp server and web proxy will also run on this SAN until they are replaced by other solutions

The idea was to use 6 10k or 15k disks for file storage (RAID 5 or 6) and 6 300 GB 15k disks for database and Exchange (RAID 10). The file storage stuff is ok but we're not sure whether it would be best to use a single 6 disk RAID 10 (900 GB)with several LUNs for Exchange or a 4 disk RAID 10 (600 GB) for Exchange and a mirror (300 GB) for the databases to separate them completely. Or a 4 disk RAID 10 with 450 GB disks giving us the same capacity but room for growth. My colleague who's in charge wants this done right - both Exchange and the databases have to be FAST and have room for growth and there has to be room for snapshots - hence the number, speed and capacity of disks. I'm really not sure what kind of disk config we should best run on this.

Don't waste disk space putting your Exchange data on RAID10, shared space on RAID5 volumes will be fine. As long as you have enough RAM in your Exchange mailbox server (4GB is AMPLE) it will need minimal (think 35-50 IOPS for 70 mailboxes) disk performance. These numbers are from official Microsoft design guides and are very liberal. If you would like a 2nd opinion HP has server design tools for Exchange at www.hp.com/go/activeanswers, the tool's recommendations are based on extensive hardware testing...

70 mailboxes won't use 100GB of data any time soon (unless your users are massive email packrats) so even a pair of 300GB 10krpm drives is too much space and ample performance for this environment.

What storage array do you want to use?

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Agreed. If you have a good SAN with at least 2GB fiber or better. Just use all 12 spindles for storage.

10k or better drives would be ideal. But more so are the RAM requirements and having enough CPU cores.

If you are using iSCSI... Unless it's equallogic, VMware and iSCSI do have some limitations that have to be worked around but aren't widely known... FC is just easier in this regard, no tweaking just setup and go.

If I had a choice I would be buying something like a Compellent SAN.

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OK... The most likely config will be:

2 VMWare servers

- an existing Proliant DL360 G5 (RAM and CPU will be upgraded as necessary)

- a new DL360 G5 with an identical configuration - my colleague would like to have 2 identical machines. I'd prefer a DL360 G6 which uses the newer Xeon 5500 series CPU's and can handle a whopping 18 memory modules. Seems a lot more future proof and cheaper when using a lot more DIMMs. 64 GB with 4 GB DIMMs is affordable if need be, the same with 8 GB DIMMs is not quite so affordable.

Storage

- an MSA2000fc

Virtualized servers

- Server 2008 Standard x64 DC and file/print

- Server 2008 Standard x64 DC and Exchange

- 3 Server 2003 Standard or Enterprise x32 for database apps. For some reason the people from the database apps from 3 different companies (all Progress databases but they each want their own server...) want lots of RAM but also W2K3 32bit because their stuff doesn't work ok W2K8 (any) or W2K3 x64. I still didn't get an answer whether they want PAE or whether they consider 4 GB "lots" of memory in which case I udnerstand 32bit. But I digress.

- Some lesser machines which will have little impact on the overall configuration

Physical servers

- a backup server with LTO tapeloader

- Netware server with Groupwise that will be phased out once migration to Exchange is complete

- database servers that will be retired once the database servers run on VMWare

I just read a paper from HP about Exchange 2007 and I'm leaning toward a mirror for Exchange ( 2 x 450 GB should be enough). The database servers use relatively small databases I'm told so I'd go for another mirror for those. Storage should be fine with a RAID 5 with 3 or 4 disks of 450 GB. I'm a fan of hot spare drives so in total we would have 8 disks, leaving 4 or 3 bays for future expansion.

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You can virtualize your backup server too! If you want to that is. There is in ESX a SCSI pass through that is supported with some backup apps like BackupExec, and I'm sure a few others.

But at the same time, the disk I/O for backup duties is high, and you would have to dedicate some spindles just for backup duties (D2D2T)

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No, we prefer a completely separate machine for backups just in case the entire SAN goes tits up. Besides they bought an entirely new machine just for the backups :)

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Make sure what ever software you use for backups, supports VCB. That is the only way to backup machines!

The only time I use agents within virtual hosts is for database type apps.

An no to agents in the service console!

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Hi.

Alot has been said about it allready, but i just thought i might give you my word of advice.

with 12 disks, i feel that the optimal storage solution you can make is the following.

1. 8 disk raid5 for both fileshares and exchange Databases.

2. 4 disk raid10 for the exchange logs.

Its not only best practice to seperate logs and storage on exchange, its putting your data in severe risk, not doing so.

Ofcause you dont need to make On huge lun of all the space on the raid10, you can use whatever you feel you need, and use the rest for extra data space for files and stuff like that. But with all database products, never mix DBs and logs on the same physical drives.

I wouldnt worry too much about performance on the exchange. I run a 1400 user installation on 24 drives, allthough its raid 50 for data and raid 10 for logs.

Second best advice i can give you. Make sure to align your partitions to 64KB, for both the log and the DB volumes. It gives in my experience upto 25+% performance, since the Exchange Database write 8 KB Pages

Regards

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Darking,

Thanks for the advice. We're dealing with only 70 users right now and it's very unlikely to grow to more than 100 over the next few years. I wonder whether it's necessary at all for us to separate logs and db's for Exchange as I'm thinking of using Continuous Replication. Combined with full backups every day I feel pretty safe. I need some more info on CCR/LCR but if you have any, you're always welcome.

Whatever those people from the database apps want, is their business. They're not very forthcoming with info on what exactly the want/need hardware-wise. For such small db's I might just give them a mirror to work on or maybe 2 mirrors, one for db and one for logs. 450 GB 15k drives should provide enough performance and disk space I think.

Can you explain a bit about LUNs? My boss talked about it as well but I can't seem to get hold of him... Is it better tu have a RAID 10 with 2 LUNs than 2 mirrors? And how will the virtual OS's themselves impact performance because they will be on the SAN as well.

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All of this is good solid information, if you weren't virtualizing all the servers.

Hi.

Alot has been said about it allready, but i just thought i might give you my word of advice.

with 12 disks, i feel that the optimal storage solution you can make is the following.

1. 8 disk raid5 for both fileshares and exchange Databases.

2. 4 disk raid10 for the exchange logs.

Its not only best practice to seperate logs and storage on exchange, its putting your data in severe risk, not doing so.

Ofcause you dont need to make On huge lun of all the space on the raid10, you can use whatever you feel you need, and use the rest for extra data space for files and stuff like that. But with all database products, never mix DBs and logs on the same physical drives.

I wouldnt worry too much about performance on the exchange. I run a 1400 user installation on 24 drives, allthough its raid 50 for data and raid 10 for logs.

Second best advice i can give you. Make sure to align your partitions to 64KB, for both the log and the DB volumes. It gives in my experience upto 25+% performance, since the Exchange Database write 8 KB Pages

Regards

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All of this is good solid information, if you weren't virtualizing all the servers.

I must admit im not an expert into virtualisation (Yet!! we are starting a 50 server migration soon into vmware.)

But its my best belief its still the safest bet to place logs and data on two physically sets of disks, please explain why this assumption isnt valid?

In my installation we are running LCR on the exchange installation. But you must understand its a replication of the running data. You cannot place them on the same volumes(physical). If you have a volume corruption, or two disks break at the same time (allthough its unlikely), you will have to restore from the last good backup. The whole point of having log files, is the ability to restore a destroyed database upto or closeto the last write to the log.

It is simply a matter of how important your users mail is. If your business can handle a whole days loss of data, then there basically isnt even a reason to have logs (other than the fact its a builtin function).

CCR is "better" it allows you to have a second mail host, but its double the windows/exchange licenses, but within budget. Again it should not be placed on the same physical disks at the the "primary" exchange server has its data.

But Mitch808, i might be misunderstanding something entirely, so please enlighten me :D

LUNs are basically just data volumes the host can see. Normally a LUN is one or more Raid groups, presented to the host as one volume.

Never SAN equipment also allows for stuff like Thin provisioning, wich basically is telling the host that it has 500gb, while only reserving fx. 200gb on the SAN, and then expanding it when the data space is needed.

I must admit i do not know much about HP MSA equipment, ive primarily worked with EMC claariion equipment(fiber channel), and we are just switching to a Iscsi SAN platform (Dell Equallogic) for our new VmWare platform.

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Make sure that with iSCSI, that you have independent VMDK's for each volume/partition, and not a singular large VMDK with partitions within it.

There is a flaw in vmware's iSCSI implementation that only opens one iSCSI connection per VMDK. Thus you will not be able to leverage the 3 1GB iSCSI ports you have on the equallogic array.

As for RAID logic in a virtual environment, it's a moot point for most (>80%) folks... Just keep it to under 2TB LUN's, keep VMDK management based on disk activity, and do not put all SQL and Exch servers on the same LUN, do some sort of logistical balance of VM's, and you're in good shape. I'll put more time into my reasoning later today.

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