You wrote: > 2012-07-23 18:37, Anonymous wrote: > > Really, it would be so helpful to know which drives we can buy with > > confidence and which should be avoided...is there any way to know from the > > manufacturers web sites or do you have to actually buy one and see what it > > does? Thanks to everyone for the info. > > I think that vendors' marking like 512e may give a clue on > their support of "emulated 512-byte sectors", whatever they > would mean by that for a specific model line.
Yeah but buying through the mail it's awfully difficult to see the vendor markings until it's too late ;) > I believe you can roughly be certain that all 3Tb HDDs except > Hitachi use 4Kb native sectors, and 4Tb disks are all 4Kb. > If these disks don't expose such sector sizing to the OS > properly, you can work around that in several ways, including, > as of recent illumos changes, an override config file for the > SCSI driver. The question was relative to some older boxes running S10 and not planning to upgrade the OS, keeping them alive as long as possible... > The main problem with "avoiding" 4kb drives seems to be just > the cases where you want to replace a single disk in an older > pool built with 512b-native sectored drives. Right, that's what we're concerned with. > For new pools (or rather new complete top-level VDEVs) this does not > matter much, except that your overheads with small data blocks can get > noticeably bigger. Understood. > There were statements on this list that drives emulating 512b > sectors (whether they announce it properly or not) are not > all inherently evil - this emulation by itself may be of some > concern regarding performance, but not one of reliability. > Then again, firmware errors are possible in any part of the > stack, of both older and newer models ;) I haven't seen any post suggesting 512b emulation didn't have very adverse effects on performance. Given how touchy ZFS seems to be I don't want to give him any excuses! Thanks for your post. _______________________________________________ zfs-discuss mailing list firstname.lastname@example.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss