RAID and WHS

[CtrlAltDel]

I've got a RocketRaid 1742 RAID-5 controller in my WHS (and a 200Gb system disk); the resulting disk doesn't appear in Windows Explorer at all. However, WHS has detected it and included it in its bucket of storage space. How can I ensure that everything gets written to the RAID array, rather than having chunks of my media end up on the non-redundant system disk?

[ExtremePC]

Originally Posted by CtrlAltDel

I've got a RocketRaid 1742 RAID-5 controller in my WHS (and a 200Gb system disk); the resulting disk doesn't appear in Windows Explorer at all. However, WHS has detected it and included it in its bucket of storage space. How can I ensure that everything gets written to the RAID array, rather than having chunks of my media end up on the non-redundant system disk?

With WHS, you can't. It will use the change left on the boot drive AND the RAID array as it sees fit, most probably both with balancing. The only way to avoid this is to have a hardware RAID that INCLUDES the boot partition, but this is not so easy to set up.

[Shan]

WHS will just see your RAID as one big disk, it has no knowledge of what protection you are adding at the hardware/firmware level. With the way WHS protects data by writing to what it thinks are multiple physical locations, you aren't really buying anything using RAID (except speed in the case of RAID 0).

Another gotcha I have read about, which I haven't confirmed is true yet, is that you should put your WHS system drive on the largest physical disk, because when you copy to a protected/duplicated WHS share everything gets written to the system drive and then balanced out from there.

Before I rebuilt my WHS last night (not happy, I really wanted the HP rather than paying for OEM on my piece of junk) I noticed I was getting warnings about system disk space when copying to the shares, which stopped a few minutes after the copy finished, which would suggest it's true as I was only using a 20GB partition for WHS. I've now made the first disk one volume and it does seem happier.

[CtrlAltDel]

That's a shame; I'd still rather you could nominate disks/partitions that would not take part in the big bucket of bits, maybe as an advanced option. That, and my desire to get some more advanced networking (QoS, bandwidth usage monitoring, proxying etc) seem to be pushing me in the direction of Linux. The one WHS feature I would most likely miss in doing that is the fire-n-forget backup system, which looks pretty handy (unless your system tries to backup a 100Gb laptop over 802.11g and constantly times out :-S ), but at least I've still got Acronis True Image to handle that.

[GlenR]

Originally Posted by Shan

Another gotcha I have read about, which I haven't confirmed is true yet, is that you should put your WHS system drive on the largest physical disk, because when you copy to a protected/duplicated WHS share everything gets written to the system drive and then balanced out from there.

That's not quiet right. WHS writes first to the primary drive before balancing. Essentially, when you install WHS you put the OS on one of the drives. WHS partions off 20GB for system and the rest is put in the pool, but this second partition is the primary drive is treated a little special. All other disks are treated as a secondary drive.

There is a good explaintion here. The main point is:

Hard Drive Partitioning
In a single hard-drive system, Windows Home Server is configured with a 20-gigabyte system partition for the Windows Home Server operating system, and the remainder of the primary hard drive is allocated to the primary data partition. Each subsequent (or secondary) hard drive is logically added to the data partition. It appears to the user as one large hard drive; however, these drives are considered to be part of the secondary data partition. In reality, your home server consists of multiple hard drives of varying sizes.
The primary data partition is used to store a unique entry for each file. If a home server has more than one hard drive, these files become “tombstones.” Tombstones are NTFS file system reparse points that Windows Home Server Drive Extender understands. They are tiny files that redirect to one or two “shadow” files on the hard drives that make up the secondary data partition. The shadow files are where your data is really stored. If folder
duplication is enabled for a Shared Folder, there will be two shadow files. If duplication is Off, there will be one shadow file.

Note The primary data partition in a home server should be as large as possible for two reasons:

 You want to provide sufficient space to grow the file table for all of the files that you will store on your home server.

 Windows Vista® and other home computer operating systems check to see if there is adequate space on the primary data partition prior to starting a copy operation.
You can add additional internal and external hard drives to your home server if you need more storage space for your folders and files. There is no need to use equal capacity hard drives—Windows Home Server will add the additional capacity of the new hard drive to the available storage on your home server.

Note In a home server with three or more hard drives, Windows Home Server Drive Extender will attempt to move all of the files off the primary data partition onto the secondary hard drives to maximize the amount of free space on the primary data partition.

Caution It is highly recommended that you not use hardware RAID technologies for your home server. Recovering from hard-drive failures becomes increasingly complex when hardware RAID systems are used. The recommended approach is to use multiple hard drives that are configured as Just a Bunch of Disks (JBOD).

Originally Posted by CtrlAltDel

That's a shame; I'd still rather you could nominate disks/partitions that would not take part in the big bucket of bits, maybe as an advanced option. That, and my desire to get some more advanced networking (QoS, bandwidth usage monitoring, proxying etc) seem to be pushing me in the direction of Linux. The one WHS feature I would most likely miss in doing that is the fire-n-forget backup system, which looks pretty handy (unless your system tries to backup a 100Gb laptop over 802.11g and constantly times out :-S ), but at least I've still got Acronis True Image to handle that.

The big pluses of WHS are low admin - yes you miss out on some high-end things, but WHS just works. And you can mix drive sizes, you don't have to ensure all drives are the same as you do in RAID.

The second is the backups. Easy and you just forget about them and they run. It will not back up a laptop if the laptop is running on batteries. Also it will not backup you 100GB laptop with all 100GB, it has built in smarts to only back up files that are unique. Sort of like a differential backup, but if the same file is on two PCs it will only keep one copy. A full explaination is here.