Abstract
Several articles have been written about ZFS including: [Managing Storage for Network Management], [More Work With ZFS], [Apache: Hack, Rollback, Recover, and Secure], and [What's Better, USB or SCSI]. This is a short article on adding a mirrored drive to an existing ZFS volume.
Background
A number of weeks ago, a 1.5 Terabyte external was added to a Sun Solaris 10 storage server. Tests were conducted to observe the differences between SCSI and USB drives, as well as UFS and ZFS filesystems. The original disk that was added will now be added to.
Inserting a new USB drive into the system is the first step. If the USB drive is not recognized upon, a discovery can be forced using the classic "disks" command, as the "root" user.
A removable (i.e. USB) drive can be labeled using the "expert" mode of the "format" command.Ultra60-root$ disks
This is what the pool appears to be before adding a mirrored diskUltra60-root$ format -e
Searching for disks...done
AVAILABLE DISK SELECTIONS:
0. c0t0d0 [SEAGATE-SX1181677LCV-C00B cyl 24179 alt 2 hd 24 sec 611]
/pci@1f,4000/scsi@3/sd@0,0
1. c0t1d0 [SEAGATE-SX1181677LCV-C00C cyl 24179 alt 2 hd 24 sec 611]
/pci@1f,4000/scsi@3/sd@1,0
2. c2t0d0 [Seagate-FreeAgent XTreme-4115-1.36TB]
/pci@1f,2000/usb@1,2/storage@4/disk@0,0
3. c3t0d0 [Seagate-FreeAgent XTreme-4115-1.36TB]
/pci@1f,2000/usb@1,2/storage@3/disk@0,0
ProcessUltra60-root$ zpool status
pool: zpool2
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
zpool2 ONLINE 0 0 0
/dev/rdsk/c2t0d0 ONLINE 0 0 0
errors: No known data errors
An individual slice can be added as a mirror to an existing disk through "zpool attach"
VerificationUltra60-root$ zpool attach zpool2 /dev/rdsk/c2t0d0 /dev/dsk/c3t0d0s0
The result of adding a disk slice to create a mirror can be checked with "zpool status"
The consumption of the CPU utilization during the resliver can be observed through "sar"Ultra60-root$ zpool status
pool: zpool2
state: ONLINE
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scrub: resilver in progress for 1h4m, 6.81% done, 14h35m to go
config:
NAME STATE READ WRITE CKSUM
zpool2 ONLINE 0 0 0
mirror ONLINE 0 0 0
/dev/rdsk/c2t0d0 ONLINE 0 0 0
c3t0d0s0 ONLINE 0 0 0
errors: No known data errors
If you are curious concerning the performance of the system during the resilvering process over the USB ports, there is "zfs iostat" command.Ultra60-root$ sar
SunOS Ultra60 5.10 Generic_141414-09 sun4u 09/16/2009
00:00:00 %usr %sys %wio %idle
00:15:01 0 40 0 60
00:30:00 0 39 0 60
00:45:00 0 39 0 61
01:00:00 0 39 0 61
01:15:00 0 39 0 61
01:30:01 0 41 0 59
...
10:45:00 0 43 0 57
11:00:00 0 40 0 59
11:15:01 0 40 0 60
11:30:00 0 40 0 59
11:45:00 0 39 0 61
12:00:00 0 43 0 56
12:15:00 0 47 0 53
12:30:01 0 44 0 56
Average 0 39 0 60
Conclusion
Ultra60-root$ zpool iostat 2 10
capacity operations bandwidth
pool used avail read write read write
---------- ----- ----- ----- ----- ----- -----
zpool2 568G 824G 12 0 1.30M 788
zpool2 568G 824G 105 0 6.92M 0
zpool2 568G 824G 156 0 9.81M 7.48K
zpool2 568G 824G 157 1 10.1M 5.74K
zpool2 568G 824G 117 6 10.3M 11.5K
zpool2 568G 824G 154 5 10.1M 7.49K
zpool2 568G 824G 222 31 8.44M 36.7K
zpool2 568G 824G 120 13 8.45M 10.2K
zpool2 568G 824G 113 4 9.75M 8.99K
zpool2 568G 824G 120 5 9.48M 11.0K
The above session demonstrates how a whole external USB device was used to create a ZFS pool and an individual slice from another USB device was used to mirror an existing pool.
Now, if I can just get this Seagate FreeAgent Xtreme 1.5TB disk to just be recognized by some system using FireWire (No, can't use it reliably on an old MacG4, Dual G5, Mac Dual Core Intel, or a dual SPARC Solaris platforms) - I would be much happier than using USB.
No comments:
Post a Comment