nathankaufman23

Abbreviated questions:

1.) In a spanned volume, do ALL associated disks need to spin up in order to access data on the volume?
2.) How is defragmentation performance on spanned volumes (understanding that each drive becomes filled to capacity before writing to the next, which is bad for defragmentation.)

Complete post / explanation:

I have a question regarding combining multiple physical disks into a single logical volume (for purposes of large-capacity storage.)

Redundancy and security are non-issues.

I have a 4-disk 1.5TB Raid-5 array for my personal data (photos, documents, important programs, information, etc.)

This spanned/striped volume is merely for combine 2 1.5TB hard drives into a single large volume for storage of media for my media center extenders and networked devices.

I used to have a 4x500GB RAID-0 array for storage of media (the same drives i turned into the Raid-5 vault) but my concern was with power consumption. Having a whopping FOUR hard drives spinning simultaneously for the purposes of watching a movie, or listening to music was unnecessary, and i was running out of space, as well.

To replace these 4 disks for storage, i purchased a pair of low-speed 5200rpm disks, which i want to combine into a single volume.

Anyways, now that I've explained my intent, and defended the fact that important data WILL be backed up on a RAID-5, and that redundancy is not an issue, which configuration is better for my needs?

1.) My first concern is dealing with the aforementioned power consumption:

- Understanding that a spanned volume works by first filling the first drive, and then once the first physical disk is full, writing additional data to the next disk in the volume, i want to know whether or not ALL disks associated with the array spin up every time data is read from the volume?

Say i have two 1.5TB drives in the volume, and the volume only has ~500GB of data written to it (so the 2nd disk in the volume is completely empty) and i write a file to the volume, do BOTH disks power and spin up? Or only the 1st disk (since that's the drive that's being written to?)

The reason i ask, is that if both drives have to spin up to read/write on the volume, then it poses no power consumption advantage over a striped array.

2.) My second concern is dealing with fragmentation.

-Understanding how spanned arrays work (as explained above) and also understanding that it is difficult (impossible) to defragment a hard drive that's close to full capacity, having no free space, i'm wondering about the defragmentation performance of a spanned volume.

If a 3TB spanned volume (consisting of 1.5TB har drives) containing MORE than 1.5TB of data (The first disk, of course, being filled TO CAPACITY with data) are programs like diskeeper still able to defragment this volume?

The reason I ask is that i'm constantly deleting recorded television/movies/ripped dvd's after i've watched them, as well as constantly adding new things, so fragmentation is a CONSTANT concern of mine. If a spanned volume offers poor fragmentation performance, then i'm better off sticking with the high power consumption of RAID-0, and striping the disks rather than spanning them.

Sorry for the long winded post, but there is a surprising lack of information regarding technical aspects of spanned volumes (as i suspect that the majority of people who use them are simply looking for additional space, and are less concerned with performance/reliability/power consumption)

If anyone has any information regarding either of these matters, please advise!!!! The sooner i figure out how to configure my discs, the sooner i can start using all of this extra space!!! (I'm hesitant to start aquiring more data than i can back up onto the 1.5TB RAID-5 before i know how i'm going to have my disks arranged, in case i need to back them up to reformat!!!)