Block allocation help?

ladyfox

Hi guys,

Any experts on block allocation out there?

I'm trying to understand the effects of increasing or decreasing block size on NTFS drives. We have a number of large storage servers at work that seem to hit some major fragmentation issues so we were looking at increasing the block size from 512 bytes/block to, well, not sure yet but something bigger. Anyone have working experience of this practice (i cant seem to find anything helpful online so even any links you can find may help.

Guess I am trying to figure out he positives and negatives of doing this and and real world practises. Whether increasing block size means i actually have to increase the memoery requirements, etc,

I appreciate this is a bit off topic but if anyone can help that would be really appreciated

dynamik

I think the default is 4k for disks over 2gb.

The larger the size, the better the performance. The lower the size, the better usage of disk space (i.e. a 1 byte file taking 512b instead of 4k). However, with current file sizes and disk sizes, I don't think the wasted space would even be noticeable. That seems low IMO.

I'm not sure how much that would actually affect things though. What is the drive(s) being used for? What RAID level, if any?

HeroPsycho

From my understanding, the only significant trade offs you have between block sizes are how much space data fragments that don't fill a block use vs. overhead of the file system and how large a partition you can have. I personally don't see a bunch of difference in fragmentation levels going either way enough to warrant my decision based on that. This becomes especially true when you're dealing with databases, since deleted contents usually becomes white space you don't recover on the storage unless you run special offline compaction commands, so disk level defrags don't do squat. You have to actually run db utilities for effective defragging.

It all comes down to your application and storage needs. Without that info, no recommendation will do you any good.

ladyfox

Sorry for the late reply.

We're not doing anything clever, just file system servers, but we do get fragmentation issues so I guess i am looking at how to reduce that. Block allocation seemed to be a viable solution, I am not sure what else. Moving to SSD?

Any thoughts? Be great to hear from anyone with some experience in this area.

tiersten

Define major fragmentation issues.

Changing the block size won't do much for fragmentation unless the majority of your files that change on a regular basis fit in a block.