V11 SP8
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Best Practices - Image Level iDataAgent

Table of Contents

Restoring Large Files

It is recommended that file-level restores from disk or volume-level backups be performed only with small files. For example, restoring a 2GB file from a disk-level backup is not recommended.

File Level Restores and Metadata Collection on AIX

Consider the following when doing a file level restore:

  • If the volume has a large number of small files (>5 million) to be restored, then turn off metadata collection, do a volume level restore, and copy the desired files back instead of running a file level restore job.
  • If the volume has a mixture of large and small files then use Scan Optimization for metadata collection.
  • If you are backing up multiple disks from the same subclient then use multi-streaming to improve performance.
  •  If there will never be a file level restore then it is recommended to turn off metadata collection.

Performance Details:

OS version AIX 6.1
dSnapChunkSize 65536
LUN Size 1.5 TB
Memory 8 GB
Processors 2

Metadata Collection Performance:

Total Number of Files : 107862987

Job ID Metadata Collection Method Scan Time Backup Time Metadata Collection Time Archive Index Time Cleanup Time Backup Size
48 Using Scan Optimization 00:03:14 03:50:17 04:54:17 00:01:43 00:00:03 516.92 MB
56 Without Scan Optimization 00:00:24 03:42:58 18:54:20 00:01:54 00:00:03 516.92 MB
64 No Metadata Collection 00:00:21 03:50:48 00:00:07 00:00:15 00:00:02 516.92 MB

Backup Performance:

  • With Scan Optimization Enabled
    JID Job Type (F or I) Number of Streams Approximate Size of Data Number of Files Size of App. Data Written Number of Extents Scan Time Backup Time Metadata Collection Time Throughput
    834 F 4 1.02 TB+ 7555148 1,106.71 GB 1,110.11 GB 566, 647 00:44:42 24:51:00 00.24:22 44.53 GB/hr
    843 I 4 100 GB+ 743032 129.98 GB 131.18 GB 66,559 00:02:39 02:40:25 00:32:34 48.90 GB/hr
    844 I 4 100 GB+ 743032 117.84 GB 119.09 GB 60,341 00:02:03 02:39:42 00:38:38 44.10 GB/hr
  • Without Scan Optimization
    JID Job Type (F or I) Number of Streams Approximate Size of Data Number of Files Size of App. Data Written Number of Extents Scan Time Backup Time Metadata Collection Time Throughput
    847 F 4 1.02 TB+ 7555148 1,146.00 GB 1,149.50 GB 586,765 00:02:18 24:04:50 01.22:44 47.59 GB/hr
    849 I 4 100 GB+ 743032 130.76 GB 131.97 GB 66,959 00:02:04 02:39:55 01:34:42 49.19 GB/hr
    850 I 4 100 GB+ 743032 120.77 GB 122.02 GB 61,840 00:01:18 02:19:35 02:02:52 51.82 GB/hr
  • Single Stream and No Scan Optimization
    JID Job Type (F or I) Number of Streams Approximate Size of Data Number of Files Size of App. Data Written Number of Extents Scan Time Backup Time Metadata Collection Time Throughput
    858 F 1 1.02 TB+ 7555148 1,146.00 GB 1,149.50 GB 586,753 00:00:20 32:00:12 01.23:04 35.81 GB/hr
    859 I 1 100 GB+ 743032 121.16 GB 122.27 GB 62,034 00:02:13 04:00:19 01:24:20 30.43 GB/hr
    860 I 1 100 GB+ 743032 141.77 GB 144.13 GB 72,590 00:01:44 03:58:04 01:30:39 28.68 GB/hr