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Solution Type Technical Instruction Sure Solution 1002348.1 : How and When to Change OPEN-V Device Geometry on Sun StorEdge[TM] 9990 and Sun StorEdge[TM] 9985
PreviouslyPublishedAs 203290 Description How and When to Change OPEN-V Device Geometry on Sun StorEdge[TM] 9990 and Sun StorEdge[TM] 9985 The OPEN-V device emulation was introduced in the Sun StorEdge[TM] 9970 (SE9970) and Sun StorEdge[TM] 9980 (SE9980) products. The cache slot / track size for the new emulation was increased in comparison to other emulations, from 48k to 64k. (See <Document: 1012382.1> for more detailed information on Sun StorEdge[TM] 9900 device geometry, including performance implications). The default cache slot and track size for OPEN-V on Sun StorEdge[TM] 9990/Sun StorEdge[TM] 9985 was increased again to 256k. However, on the newest arrays, one has the option of using the new, larger track/slot size, or presenting the older 64k geometry to attached hosts. This article discusses potential situations under which each OPEN-V option might be advantageous, and provides procedures for changing OPEN-V device geometry. Steps to Follow Please review the following steps. The circumstances under which one might want to use the "older" OPEN-V device geometry on SE9990 or SE9985 may already be readily apparent to the reader. For example, if the user wants to employ a host-based volume manager to mirror between different array architectures, it will be necessary to make the devices from each array appear to be exactly equivalent in size and geometry, and hence capable of being mirrored. In this case one would want to take advantage of the 9990/85's capability to present the older (64k) OPEN-V device geometry. Theoretically, cache hit rates with primarily small, random read workloads might be better with the smaller, 64k track/slot size also. This is because the 9900 arrays always stage a minimum of 1 track of data into cache, regardless of how small the read request may be. If an application does very random reads of 8k, for example, it may not be efficient to stage an entire 256k of data, but this is what will occur by default with OPEN-V on SE9990/85. The author conducted testing of both types of OPEN-V device geometry available on SE9990/85. Vdbench was used to compare performance of both types of OPEN-V geometry with a variety of workloads, including small random reads, small random and sequential writes, a mixture of small random reads with small sequential writes, large sequential reads, and so on. Only one test was found in which either geometry had a significant performance advantage. On a test of small (8k) sequential reads, the new 256k track/slot size had a modest advantage. With the default (256k) slot/track size, a multithreaded sequential read on four raw OPEN-V devices on four different parity groups obtained an average of 10829 I/O operations per second (IOPS) and 84.6 MB/second. The same test on the same physical devices, now presented with the 64k slot/track size, obtained 8846 IOPs and 69.1 MB/second. This result implies that the newer OPEN-V device geometry may be preferred for performance reasons, at least in data warehouse environments. OPEN-V device geometry is configured either globally, via system option mode 313, or for specific host groups, via host group option mode 16. At this writing, neither of these modes can be set by end users, but rather must be configured by authorized Sun field service representatives. Instructions for setting OPEN-V device geometry are included in the Sun Internal-Use Only section, below. Product Sun StorageTek 9990 System Sun StorageTek 9985 System Sun StorageTek 9980 System Sun StorageTek 9970 System Sun StorageTek 9900V Series Array Internal Comments For Internal Sun use only.
Instructions for setting host group option mode 16 can be found
Note that Hitachi requires that attached hosts should be
Under Solaris, the default VTOC for SE9990/85 OPEN-V will have # prtvtoc /dev/rdsk/c4t60060E8004275000000027500000006Bd0s2
With host group option mode 16 or system option mode 313 enabled # prtvtoc /dev/rdsk/c4t60060E80042750000000275000000081d0s2
If a host power cycle is not possible, the following method for
A sample of the relabeling described above is provided below, format> di 34 OPEN-V, HDS, SE99, track, slot, sector, block, Hitachi, device, geometry, LDEV, option, mode Previously Published As 84423 Change History Date: 2007-11-13 User Name: 7058 Action: Approved Comment: Changed internal sunsolve2 reference in external section to sunsolve.sun.com Version: 6 Date: 2007-11-13 User Name: 7058 Action: Update Started Comment: Fix links Version: 0 Date: 2007-05-25 User Name: 31620 Action: Approved Comment: Verified Metadata - ok Verified Keywords - ok Verified still correct for audience - currently set to contract Audience left at contract as per FvF at http://kmo.central/howto/content/voyager-contributor-standards.html Checked review date - currently set to 2007-07-27 (bit short, but OK) Checked for TM - ok as presented Publishing under the current publication rules of 18 Apr 2005: Checked for the word normalized - not present Version: 5 Attachments This solution has no attachment |
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