Hi! > >> > Would it be possible to have a custom block device driver read/write > >> > in increments of 12k instead of reading/writing data in 4k increments? > >> > In other words, I would like to change the default page size on a > >> > x86_64 platform (4.4.0 kernel) from 4k to 12k as the minimum page > >> > size? I understand I may have negative performance due to > >> > fragmentation. Any help would be appreciated. > >> > > >> > If this is the wrong mailing list, please let me know the right one to > >> > use. > >> > >> I won't say "no" but ammount of work neccessary is likely measured in > >> man-years. Plus, hardware page size _is_ 4KB. > > > > Or a few other much larger sizes. Not that it actually matters. You can > > implement a larger software page size for a platform but it would still > > neeed to be a power of two, and you'd have trouble running some existing > > binaries for x86. > > > > What problem are you *actually* trying to solve ? > > Thanks for responding! I work for a company that created custom > hardware with 4 banks of drives. Each bank is 12 terabytes; and each > bank is controlled by a separate RAID controller. We created a custom > block device driver that is responsible for moving data to each bank. > The RAID controller will then stripe the data across the appropriate > disks for the specified bank. The problem we are having is by moving > in increments of 4k, we are unable to utilize all 48 terabytes; we are > only able to utilize 32 terabytes. If we could move in increments of > 12K that would allow us to use the full 12 terabytes for each bank.
12TB is not that big.. are we talking spinning rust or something special? I mean, what does it have to do with page size? 48TB device, that's 5 SATA drives... that's not even that big. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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