Interesting, I didn't realize that Soracle was working on/had a solution somewhat in place for 4K-drives. I wonder what will happen first for me, Hitachi 7K2000s hitting a reasonable price, or 4K/variable-size sector support hiting so I can use Samsung F4s or Barracuda LPs.
On Tue, Nov 23, 2010 at 9:40 AM, David Magda <dma...@ee.ryerson.ca> wrote: > On Tue, November 23, 2010 08:53, taemun wrote: >> zdb -C shows an shift value on each vdev in my pool, I was just wondering >> if it is vdev specific, or pool wide. Google didn't seem to know. >> >> I'm considering a mixed pool with some "advanced format" (4KB sector) >> drives, and some normal 512B sector drives, and was wondering if the >> ashift can be set per vdev, or only per pool. Theoretically, this would >> save me some size on metadata on the 512B sector drives. > > It's a per-pool property, and currently hard coded to a value of nine > (i.e., 2^9 = 512). Sun/Oracle are aware of the new, upcoming sector size/s > and some changes have been made in the code: > > a. PSARC/2008/769: Multiple disk sector size support > http://arc.opensolaris.org/caselog/PSARC/2008/769/ > b. PSARC/2010/296: Add tunable to control RMW for Flash Devices > http://arc.opensolaris.org/caselog/PSARC/2010/296/ > > (a) appears to have been fixed in snv_118 or so: > > http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6710930 > > However, at this time, there is no publicly available code that > dynamically determines physical sector size and then adjusts ZFS pools > automatically. Even if there was, most disks don't support the necessary > ATA/SCSI command extensions to report on physical and logical sizes > differences. AFAIK, they all simply report 512 when asked. > > If all of your disks will be 4K, you can hack together a solution to take > advantage of that fact: > > http://tinyurl.com/25gmy7o > http://www.solarismen.de/archives/5-Solaris-and-the-new-4K-Sector-Disks-e.g.-WDxxEARS-Part-2.html > > > Hopefully it'll make it into at least Solaris 11, as during the lifetime > of that product there will be even more disks with that property. There's > also the fact that many LUNs from SANs also have alignment issues, though > they tend to be at 64K. (At least that's what VMware and NetApp best > practices state.) > > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss > -- --khd _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
