Hello.
I've just built my first NAS server, but have issues with the Samsung drives used.
Im aware that they use the new 4K sectors instead of the common 512b ones.
Installed the FreeNAS-8.0.1-BETA3-amd64 version of FreeNAS, which allows to tick the 4K checkbox when creating a RAIDZ volume.
I did the dd-read/write tests;
Im a bit dazzled how the write actually is almost twice as fast as reading from the drives. How is that possible?
Other people report 'normal' r/w speeds;
http://hardforum.com/showthread.php?t=1561366
I've read multiple posts here on the freenas board, but still wonder how to proceed.
Samsung drive thread 4K / 512b
http://forums.freenas.org/showthread.php?199-Samsung-HD204UI-2TB-4k-or-512
zdb gives this; (ashift = 12, as opposed to 9, indicating 4K sectors..)
Ive also done a diskutil to verify the 4K configuration;
The RAIDZ volume reports only 5.1 TB available space, the same issue this guy faces;
http://forums.freenas.org/showthread.php?905-RaidZ-and-4x2Tb-yeilds-5.3Tb-available-space-is-this-right
I guess a rough estimate would be that 1/N-drivespace 'dissappears' when creating a RAIDZ/RAID5 volume, but this seems a little to much?
I know that there is an issue with a batch of Samsung HD204UI 2TB drives, Rev A manufactured last year (2010). Luckily my drives are newer than those, and probably not affected by this issue.
My current build is:
4x 2TB Samsung HD204UI
4GB Ram
Gigabyte D525 Motherboard (ATOM 1.8GHZ)
Any hints/tips/ideas would be very welcome.
Thanks for reading a newbie's post.
Andreas.
I've just built my first NAS server, but have issues with the Samsung drives used.
Im aware that they use the new 4K sectors instead of the common 512b ones.
Installed the FreeNAS-8.0.1-BETA3-amd64 version of FreeNAS, which allows to tick the 4K checkbox when creating a RAIDZ volume.
I did the dd-read/write tests;
Code:
freenas# dd if=/dev/zero of=/mnt/nas/ddfile bs=1m count=10000 10000+0 records in 10000+0 records out 10485760000 bytes transferred in 57.899730 secs (181102053 bytes/sec) freenas# dd if=/mnt/nas/ddfile of=/dev/zero bs=1m count=10000 10000+0 records in 10000+0 records out 10485760000 bytes transferred in 101.018096 secs (103800808 bytes/sec)
Im a bit dazzled how the write actually is almost twice as fast as reading from the drives. How is that possible?
Other people report 'normal' r/w speeds;
http://hardforum.com/showthread.php?t=1561366
I've read multiple posts here on the freenas board, but still wonder how to proceed.
Samsung drive thread 4K / 512b
http://forums.freenas.org/showthread.php?199-Samsung-HD204UI-2TB-4k-or-512
zdb gives this; (ashift = 12, as opposed to 9, indicating 4K sectors..)
Code:
nas version=15 name='nas' state=0 txg=2596 pool_guid=7692156913126981140 hostid=3781610956 hostname='' vdev_tree type='root' id=0 guid=7692156913126981140 children[0] type='raidz' id=0 guid=8960000534887433963 nparity=1 metaslab_array=23 metaslab_shift=36 ashift=12 asize=7992986566656 is_log=0 children[0] type='disk' id=0 guid=16499009846811762149 path='/dev/gptid/b040bc5d-a8d8-11e0-8354-1c6f65ff36d1' whole_disk=0 children[1] type='disk' id=1 guid=6775391256335755402 path='/dev/gptid/b15d47d3-a8d8-11e0-8354-1c6f65ff36d1' whole_disk=0 children[2] type='disk' id=2 guid=11791736992082363252 path='/dev/gptid/b247551b-a8d8-11e0-8354-1c6f65ff36d1' whole_disk=0 children[3] type='disk' id=3 guid=10837461982030907558 path='/dev/gptid/b337913d-a8d8-11e0-8354-1c6f65ff36d1' whole_disk=0
Ive also done a diskutil to verify the 4K configuration;
Code:
freenas# diskinfo -v /dev/ada0 /dev/ada0 512 # sectorsize 2000398934016 # mediasize in bytes (1.8T) 3907029168 # mediasize in sectors 0 # stripesize 0 # stripeoffset 3876021 # Cylinders according to firmware. 16 # Heads according to firmware. 63 # Sectors according to firmware. S2H7JD2B422328 # Disk ident. freenas# diskinfo -v /dev/ada1 /dev/ada1 512 # sectorsize 2000398934016 # mediasize in bytes (1.8T) 3907029168 # mediasize in sectors 0 # stripesize 0 # stripeoffset 3876021 # Cylinders according to firmware. 16 # Heads according to firmware. 63 # Sectors according to firmware. S2H7JD2B422335 # Disk ident. freenas# diskinfo -v /dev/ada2 /dev/ada2 512 # sectorsize 2000398934016 # mediasize in bytes (1.8T) 3907029168 # mediasize in sectors 0 # stripesize 0 # stripeoffset 3876021 # Cylinders according to firmware. 16 # Heads according to firmware. 63 # Sectors according to firmware. S2H7JD2B422332 # Disk ident. freenas# diskinfo -v /dev/ada3 /dev/ada3 512 # sectorsize 2000398934016 # mediasize in bytes (1.8T) 3907029168 # mediasize in sectors 0 # stripesize 0 # stripeoffset 3876021 # Cylinders according to firmware. 16 # Heads according to firmware. 63 # Sectors according to firmware. S2H7JD2B422330 # Disk ident.
The RAIDZ volume reports only 5.1 TB available space, the same issue this guy faces;
http://forums.freenas.org/showthread.php?905-RaidZ-and-4x2Tb-yeilds-5.3Tb-available-space-is-this-right
I guess a rough estimate would be that 1/N-drivespace 'dissappears' when creating a RAIDZ/RAID5 volume, but this seems a little to much?
I know that there is an issue with a batch of Samsung HD204UI 2TB drives, Rev A manufactured last year (2010). Luckily my drives are newer than those, and probably not affected by this issue.
My current build is:
4x 2TB Samsung HD204UI
4GB Ram
Gigabyte D525 Motherboard (ATOM 1.8GHZ)
Any hints/tips/ideas would be very welcome.
Thanks for reading a newbie's post.
Andreas.