2
2
I have 3 hdd, with the next camcotrol
identify.
root@cirmos:/root # camcontrol identify ada1
pass2: <WDC WD10EZEX-00RKKA0 80.00A80> ATA-8 SATA 3.x device
pass2: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes)
protocol ATA/ATAPI-8 SATA 3.x
device model WDC WD10EZEX-00RKKA0
firmware revision 80.00A80
serial number WD-WMC1S4587539
WWN 50014ee003930f6e
cylinders 16383
heads 16
sectors/track 63
sector size logical 512, physical 4096, offset 0
LBA supported 268435455 sectors
LBA48 supported 1953525168 sectors
PIO supported PIO4
DMA supported WDMA2 UDMA6
Feature Support Enabled Value Vendor
read ahead yes yes
write cache yes yes
flush cache yes yes
overlap no
Tagged Command Queuing (TCQ) no no
Native Command Queuing (NCQ) yes 32 tags
SMART yes yes
microcode download yes yes
security yes no
power management yes yes
advanced power management no no
automatic acoustic management no no
media status notification no no
power-up in Standby yes no
write-read-verify no no
unload no no
free-fall no no
data set management (TRIM) no
root@cirmos:/root #
as can see above, the sector size is detected as:
sector size logical 512, physical 4096, offset 0
Here is already some topics on 4k drive tuning. I want create ZFS (raidz) from above 3 drives, and have the next questions:
- Are these drives
4k drives
? (asking because the physical sector size is 4k but logical is reported as 512b) - what is the recommended
gpart
for the above divers to getcorrect alignment
(Want create onefreebsd-zfs
partition) - Is here zpool tuning what i should consider? (the root, system and swap should be not in the above drives - these drives are only for "pure" file storage (and home directories).
The "best practice" of "feding ZFS the whole disk" is a Solaris-ism that does not apply to FreeBSD. Under Solaris ZFS would disable caching if "fed" a partition vs. a real disk. FreeBSD has no such issue. – Adam Strohl – 2015-04-17T05:27:50.567
@AdamStrohl Meh. (that's a technical term.) If you think that proposing to feed ZFS partitions instead of whole drives is a great idea, then propose it as an answer, with sources that say it is such a [great idea] (inside or outside FreeBSD). (hint, it isn't anything resembling a great (or even good) idea.) – killermist – 2015-04-23T16:07:12.743
@killermist I've submitted as an answer. I've run across a few places were "partitions are fine" has been clearly stated: http://lists.freebsd.org/pipermail/freebsd-questions/2013-January/%E2%80%A6 and http://forums.freebsd.org/threads/zfs-and-disk-labeling-question.33896 among others.
Additionally we have dozens of clients with ZFS under partitions in production spanning many, many servers. What specifically "isn't a great idea" about this? Maybe I can do some testing?
By giving ZFS the entire drive, you're also accepting the risk that if in the future you'll need to replace the drive that failed and the replacement you'll buy has even one sector fewer than the old disk, you won't be able to use it.
IMO, a better practice is to create a partition that's a slightly smaller than the entire disk. Such margin would allow you to use other disk models of the "same" capacity. – Marcin Kaminski – 2014-03-03T18:08:26.293
Meh. But to elaborate, how often do replacement drives (especially with time being an element of consideration) DECREASE in size? – killermist – 2014-04-17T00:03:22.773
1I've had this happen to me twice in the past. I'd rather set it up the way that takes out the potential for guesswork out of the process in the future. – Marcin Kaminski – 2014-04-22T13:04:50.767