Description
How can I tell if a SnapVault rollback is progressing?
SnapVault remains in a quiescing state after the transfer has been aborted.
Procedure
During the rollback process that occurs after an aborted SnapVault transfer, the storage controller takes a new snapshot of the filesystem in its present state with the data incompletely transferred. Then it performs a filesystem comparison between the current SnapVault base snapshot and the new one, reverting changes to the base snapshot along the way. This occurs until the filesystem has returned to its former consistent state. After the process completes, both cleanup and base snapshots are removed and a new base snapshot for that SnapVault or qtree SnapMirror relationship is created.
There is no sure-fire way to speed up a rollback operation. Since it is a background process on a busy storage controller, user operations such as Network File System (NFS), Common Internet File System protocol (CIFS), iSCSI, and FCP data transfer will take precedence. The number of inodes and kilobytes to be rolled back and the ongoing system load (CPU and disk) both affect its duration. Once a rollback has started, there's no way to stop or abort the process.
However, it is possible to determine what sort of progress is being made with the rollback operation over a period of time by examining the number of changed kilobytes between the base and cleanup snapshots in the output of the snap delta command, and comparing it to the rate of change as shown in df command for a given period of time. This is easier to do with volumes that contain fewer SnapVault destinations.
It is also possible to see the number of inodes that will be removed from the active filesystem by examining the output of snapvault status -l on the SnapVault primary system. Because SnapVault replicates inodes before actual user data, the active filesystem will lose the number of inodes listed in Total files to transfer rather than total files transferred.
# snapvault status -l
Source: ossv:/usr
Destination: controller:/vol/sv_sec_dest/ossv-usr
Status: Idle with restart checkpoint
State: Source
Lag: -
Mirror Timestamp: -
Base Snapshot: -
Current Transfer Type: -
Contents: -
Last Transfer Type: -
Last Transfer From: -
Last Transfer Size: 6242 MB
Last Transfer Duration: 00:27:28
Total files to transfer: 733547
Total files transferred: 529365
Current File Size: 4608
Current File Progress: 4608
Current File Name: /usr/test/file-545233
Transfer Error ID: -
Transfer Error Message: -
In the example below, the cleanup snapshot has just been created. The snap delta command tells us that 4248144-kilobyte (KB) of changes separate the base snapshot from the cleanup snapshot.
Volume sv_sec_dest
From Snapshot To KB changed Time Rate (KB/hour)
--------------- -------------------- ----------- ------------ ---------------
-cleanup.0 Active File System 211416 2s 380548800.000
-base.5 -cleanup.0 4248144 0d 02:07 2002791.828
From Snapshot To KB changed Time Rate (KB/hour)
--------------- -------------------- ----------- ------------ ---------------
-base.5 Active File System 4459560 0d 02:07 2101913.589
Filesystem kbytes used avail capacity Mounted on
/vol/sv_sec_dest/ 16777216 7894212 8883004 47% /vol/sv_sec_dest/
/vol/sv_sec_dest/.snapshot 4194304 129404 4064900 3% /vol/sv_sec_dest/.snapshot
Filesystem iused ifree %iused Mounted on
/vol/sv_sec_dest/ 884747 1115241 44% /vol/sv_sec_dest/
After 21 seconds, the df command shows 600-megabyte (MB) of changes and 210000 files have been removed from the active filesystem.
After an additional 15 seconds:
Volume sv_sec_dest
From Snapshot To KB changed Time Rate (KB/hour)
--------------- -------------------- ----------- ------------ ---------------
-cleanup.0 Active File System 244768 23s 38311513.043
-base.5 -cleanup.0 4248144 0d 02:07 2002791.828
From Snapshot To KB changed Time Rate (KB/hour)
--------------- -------------------- ----------- ------------ ---------------
-base.5 Active File System 4492912 0d 02:07 2111827.027
Filesystem kbytes used avail capacity Mounted on
/vol/sv_sec_dest/ 16777216 7321080 9456136 44% /vol/sv_sec_dest/
/vol/sv_sec_dest/.snapshot 4194304 760476 3433828 18% /vol/sv_sec_dest/.snapshot
Filesystem iused ifree %iused Mounted on
/vol/sv_sec_dest/ 670298 1329690 34% /vol/sv_sec_dest/
After 46 seconds, an additional 2.4-gigabyte (GB) of data has been removed from the active filesystem. We can see the destination volume's snapshot usage growing, as well.
After an additional 61 seconds:
Volume sv_sec_dest
From Snapshot To KB changed Time Rate (KB/hour)
--------------- -------------------- ----------- ------------ ---------------
-cleanup.0 Active File System 328400 59s 20037966.101
-base.5 -cleanup.0 4248144 0d 02:07 2002791.828
From Snapshot To KB changed Time Rate (KB/hour)
--------------- -------------------- ----------- ------------ ---------------
-base.5 Active File System 4576544 0d 02:08 2141073.216
Filesystem kbytes used avail capacity Mounted on
/vol/sv_sec_dest/ 16777216 4888680 11888536 29% /vol/sv_sec_dest/
/vol/sv_sec_dest/.snapshot 4194304 3275068 919236 78% /vol/sv_sec_dest/.snapshot
Filesystem iused ifree %iused Mounted on
/vol/sv_sec_dest/ 366428 1633560 18% /vol/sv_sec_dest/
For systems undergoing a very large rollback, a second-by-second look will not be as useful as comparing the amount of data that is removed over a longer period of time, such as 30 minutes or an hour.
Afer 84 seconds:
Volume sv_sec_dest
From Snapshot To KB changed Time Rate (KB/hour)
--------------- -------------------- ----------- ------------ ---------------
-cleanup.0 Active File System 384828 0d 00:01 18471744.000
-base.5 -cleanup.0 4248144 0d 02:07 2002791.828
From Snapshot To KB changed Time Rate (KB/hour)
--------------- -------------------- ----------- ------------ ---------------
-base.5 Active File System 4632972 0d 02:08 2162974.867
Filesystem kbytes used avail capacity Mounted on
/vol/sv_sec_dest/ 16777216 4005872 12771344 24% /vol/sv_sec_dest/
/vol/sv_sec_dest/.snapshot 4194304 4410556 0 105% /vol/sv_sec_dest/.snapshot
Filesystem iused ifree %iused Mounted on
/vol/sv_sec_dest/ 231544 1768444 12% /vol/sv_sec_dest/
Finally, there are no more rollback changes to be made so the base and cleanup snapshots will be removed.
After 97 seconds:
Volume sv_sec_dest
From Snapshot To KB changed Time Rate (KB/hour)
--------------- -------------------- ----------- ------------ ---------------
-base.6 Active File System 17936 5s 12913920.000
Filesystem kbytes used avail capacity Mounted on
/vol/sv_sec_dest/ 16777216 3600504 13176712 21% /vol/sv_sec_dest/
/vol/sv_sec_dest/.snapshot 4194304 476 4193828 0% /vol/sv_sec_dest/.snapshot
Filesystem iused ifree %iused Mounted on
/vol/sv_sec_dest/ 166002 1833986 8% /vol/sv_sec_dest/
If you need further assistance, post a question in the NetApp Support Community.
阅读(645) | 评论(0) | 转发(0) |
