Yes, a power supply failure will disable write caching. The FLARE release notes list the following requirements for the Cx3-10,20, and 40.
For write caching: ¿ Five disks minimum, installed in slots 0 through 4 of enclosure 0 ¿ Two storage processors ¿ Four power supplies ¿ One standby power supply (SPS)
Unfortunately, the wording in the Release Notes is not quite right....
Specifically for the CX3-10, CX3-20, and CX3-40 class arrays which all have qty 4 Power Supplies in the SPE; Write Cache will remain enabled as long as any 3 of those 4 Power Supplies are operating correctly. In other words, the failure of a single Power Supply in the SPE in the above noted arrays will not result in Write Cache disabling. If a second Power Supply in the SPE fails, then Write Cache will disable.
Additionally, in the DAE that contain the Vault drives (the DAE at Bus 0 Enclosure 0), both of that DAE's power supplies must be operating correctly for Write Cache to be enabled (this is not mentioned in the Release Notice).
We will clarify the Release Notes in this area, in the next update.
Aran, The Navisphere online help is more accurate - path "Managing Storage Systems", "Caching", "Hardware requirements for write caching". For the CX3-10/20/40 it correctly notes "3 out of 4" for the power supplies (SPE power supplies). Release Note information will be clarified in the next update; we'll also see about creating a Knowledgebase (Primus) article to more clearly cover this area.
AranH1
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July 17th, 2008 07:00
For write caching:
¿ Five disks minimum, installed in slots 0 through 4 of enclosure 0
¿ Two storage processors
¿ Four power supplies
¿ One standby power supply (SPS)
nandas
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July 17th, 2008 08:00
AranH1
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July 17th, 2008 08:00
AnaA
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RRR
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ovivier
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July 21st, 2008 05:00
DGM3
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July 23rd, 2008 21:00
Specifically for the CX3-10, CX3-20, and CX3-40 class arrays which all have qty 4 Power Supplies in the SPE; Write Cache will remain enabled as long as any 3 of those 4 Power Supplies are operating correctly. In other words, the failure of a single Power Supply in the SPE in the above noted arrays will not result in Write Cache disabling. If a second Power Supply in the SPE fails, then Write Cache will disable.
Additionally, in the DAE that contain the Vault drives (the DAE at Bus 0 Enclosure 0), both of that DAE's power supplies must be operating correctly for Write Cache to be enabled (this is not mentioned in the Release Notice).
We will clarify the Release Notes in this area, in the next update.
Regards,
DGM
AranH1
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July 24th, 2008 07:00
AranH1
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July 24th, 2008 10:00
DGM3
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July 24th, 2008 10:00
The Navisphere online help is more accurate - path "Managing Storage Systems", "Caching", "Hardware requirements for write caching". For the CX3-10/20/40 it correctly notes "3 out of 4" for the power supplies (SPE power supplies). Release Note information will be clarified in the next update; we'll also see about creating a Knowledgebase (Primus) article to more clearly cover this area.
Regards,
DGM