Shadow set I/O

Management of storage subsystems: SAN, volume shadowing, logical disks, file systems, and more.
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fdroste
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Shadow set I/O

Post by fdroste » Sun Mar 13, 2022 2:35 pm

My system disk has 3 members, currently in a merge state stuck at 0% merged
Also getting console messages:
%SHAD-I-VOLPROC, DSA0: 5 Mount verification messages have been suppressed in past 370 seconds.
No disk members are being ejected from the shadow set.

Q: are writes to DSA0: still happening to all 3 members or only to the master member ?

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volkerhalle
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Re: Shadow set I/O

Post by volkerhalle » Mon Mar 14, 2022 12:23 pm

It is my understanding, that a MERGE operation just makes sure all members are identical block-by-block. Shadowset writes should still continue to go to all valid members.

You can try to verify this by writing a big file to the shadowset and watch the 'Operations completed' with SHOW DEV/FULL for all 3 members. That count should equally increase for all 3 members. If the disk is otherwise busy, reads should be more or less equally be distributed over all 3 members.

$ ANALYZE/SYSTEM
SDA> SHOW DEV DSAx

might give you some more information. Look at the SHAD (3rd page of the display).

Volker.

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