Need advice about af disk and "allocation size"

BonzaiDuck

Lifer
Jun 30, 2004
16,055
1,683
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I'm up to my a** in alligators today.

I'm adding two new 2TB NAS drives to my WHS [Win 2008 R2] server system.

Both Win 7 and WHS 2011 have an update patch which functions as an emulation approach to dealing with AF drives.

Previously, since all my drives are 1TB or less, when creating Simple Volumes on these disks (AF or not) -- I'd chosen the "default" "allocation size" which (if not mistaken) is "512."

IF -- "allocation size" is "sector size," then this choice affects efficiency as well as performance for different kinds of files. Things like "movies" and DVR-captures may benefit some from one sector-size choice; smaller files from another (and I think in this case -- smaller, like "512.")

My server is waiting for me to choose in the dialog box for "disks and storage" as I initialize the new 2TB NAS drive.

Suggestions? Somebody should have more thorough and detailed information about this.

Also, if I choose "4096," there may be a mix of drives including some with "512." I assume that managing this is taken care of at the hardware level, or that I won't experience any reliability or other difficulties down the road.

Who knows, and who can tell me?!
 
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BrightCandle

Diamond Member
Mar 15, 2007
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The problem is your mixing and matching underlying allocation sizes in the same raid array, no matter what you do its going to impact performance. Personally I would go with the allocation size of the new disks, the other drives will then just be using multiple sectors to accomodate it but that only improves performance for larger files anyway. It wastes space on smaller files but at least you avoid running emulation for the new drives based on 4k sectors which does impact on performance quite significantly.
 

BonzaiDuck

Lifer
Jun 30, 2004
16,055
1,683
126
The problem is your mixing and matching underlying allocation sizes in the same raid array, no matter what you do its going to impact performance. Personally I would go with the allocation size of the new disks, the other drives will then just be using multiple sectors to accomodate it but that only improves performance for larger files anyway. It wastes space on smaller files but at least you avoid running emulation for the new drives based on 4k sectors which does impact on performance quite significantly.

I found some other non-anand forum discussions about this, and it begs more of my attention which I cannot cram in right now. There seems to be a confusion about sector-size and cluster-size in this mix. Others seem to think -- because the Win-7 and WHS OS's both use this "emulation" feature, I should just choose "default."

Likely by this afternoon or tonight, there wouldn't otherwise be a worry about "mixing" -- all the older drives will be "outta-there" and not part of the drive pool. I'll come back to see if there's more input on this.
 

BonzaiDuck

Lifer
Jun 30, 2004
16,055
1,683
126
UPDATE: The "allocation size" option that pops up at format time is apparently "cluster size" as opposed to the distinguishing feature of AF drives. A Microsoft web-article suggests choosing the default at format time for these 2TB drives and an assortment of sizes. This may affect performance if large media files are outside the range for this parameter, so I can only guess that it matters at all if your media files are somehow more important than "regular" data.

Now if I can only be patient while the StableBit Scanner finishes with its evaluation of "disk health" for the first NAS drive I've installed. . . .

Somebody else posted lab reviews about different makes of HDDs, and Seagate didn't fare all that well. But it depends on the drive model among other things. Somebody who gives tech-support for software related to drive health told me they had several of these NAS drives -- didn't have any more problems than you'd get with other makes and models . . . soooo. . . . .