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Urgent from Sybase: Sybase IQ archives created with a BACKUP statement using more than 36 devices may not be restorable.

Summary: This document describes a situation where Sybase IQ database backup archives are created without error but the subsequent restore using these backups return a "Tapes out of order" error.


Contents

This document contains the following sections:

  • Customer Alert
  • Recommendation

Customer Alert

When using the BACKUP command of Sybase IQ, users can parallelize the operation to multiple devices by specifying multiple TO clauses. Backups created using a backup statement with more than 36 TO clauses create backup archives that may be unreliable. While these archives appear to be correctly written, they may contain invalid headers and cannot be restored. The Sybase IQ BACKUP command provides no diagnostics or alerts that indicate that the archives have been written incorrectly. There is no current method to test the validity of the archives without performing a restore using the archives.

This alert affects all versions of Sybase IQ up to and including Sybase IQ 12.7 ESD #5.

This alert also affects all versions of Sybase Risk Analytics Platform, and Sybase RAP - The Trading Edition.

Recommendation

Corrective Actions for Existing Backup Archives

Sybase strongly recommends that customers who have created backup archives to more than 36 devices test the archives by restoring them to a test area. Do not attempt to restore the archive to a production database unless this test has completed successfully. If the test restore fails, create new backup archives using 36 or fewer TO clauses.

Corrective Actions for Future Backups

Users must create future backups using 36 or fewer TO clauses.

Keep backup commands small. Do not to go to extremes with the number of devices as it will only cause I/O and hardware contention with more devices. As a practical guideline, use roughly 1 device per core on the machine to saturate CPU usage. Use up to 2 per core on faster systems.

Future Versions

Versions of IQ from 12.7 ESD #6 and 12.6 ESD #11 will enforce a limit of 36 devices in a BACKUP command. Full versions beyond 12.7 will also enforce this limit.

Tracking

Sybase is tracking this issue under CR# 543249.

This CR will be fixed in the following EBFs, and ones that supersede them. The EBFs will be available in Q1 2009.

Platform IQ 12.6 IQ 12.7
EBF# (ESD# 11) EBF# (ESD# 6)
IBM AIX (Power) 64-bit 16209 16220
HP-UX (PA-RISC) 64-bit 16210 16221
HP-UX (Itanium) 64-bit 16211 16222
Linux (x86) 32-bit 16212 16223
Linux (x86) 64-bit 16213 16224
Linux (P-Series) 64-bit 16214 16225
Sun Solaris (x86) 64-bit 16215 16226
Sun Solaris (Sparc) 64-bit 16216 16227
Windows (x86) 32-bit 16217 16228
Windows (x86) 64-bit 16218 16229

Customers using Sybase Risk Analytics Platform, or Sybase RAP - The Trading Edition, should use the appropriate EBF for their platform listed in the previous table, based on the information in the table below.

Software Version & ESD#
RAP - The Trading Edition IQ 12.7 ESD# 6
Risk Analytics Platform v3.0 IQ 12.6 ESD# 11
Risk Analytics Platform v2.0 IQ 12.6 ESD# 11
Risk Analytics Platform v1.0 IQ 12.6 ESD# 11

Downloads

EBFs are obtained from the Sybase EBFs and Maintenance site.

http://downloads.sybase.com/

Follow the instructions in the EBF cover letter to install the EBF.

If you require further assistance please contact your local support center. The contact numbers can be found in the About Support section under Support & Services at the www.sybase.com website.

http://www.sybase.com/contactus/support


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