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Strange results from 'evaperf vdts'

Nelson Jeppesen
Occasional Contributor

Strange results from 'evaperf vdts'

So I've been having lots of performance issues with the EVA but HP support offers no answers.

So I'm looking at 'evaperf vdts' (Virtual Disk Transfer Size) and I see lots of 0 < 2k transferers. I'm a little confused; We see the NTFS cluster size to 64k. How can the transfer size be 2k (or less)?


ID 0 2K 4K 8K 16K 32K 64K 128K 256K 512K Ctlr LUN Node
< < < < < < < < < <=
2K 4K 8K 16K 32K 64K 128K 256K 512K INF
-- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ---- --------------------------------------------------------- --------
59 996 0 6 1 0 0 0 0 0 0 300A SQLogs NL-SAN
59 1000 2 4 0 0 0 0 0 0 0 400S SQLLogs NL-SAN

3 REPLIES
Nelson Jeppesen
Occasional Contributor

Re: Strange results from 'evaperf vdts'

Re-formated to easier reading

2K 4K 8K 16K 32K 64K 128K 256K 512K INF
996 0 6 1 0 0 0 0 0 0 SQLLogs
1000 2 4 0 0 0 0 0 0 0 SQLLogs
Uwe Zessin
Honored Contributor

Re: Strange results from 'evaperf vdts'

The "cluster size" or "block size" of a file system just defines the smallest allocation unit covered by a single free/used bit - it does not imply that the OS I/O size is fixed to this value and the driver is then doing blocking/de-blocking, because the application does smaller I/Os.
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Nelson Jeppesen
Occasional Contributor

Re: Strange results from 'evaperf vdts'

So lots of 2k IO to SQL logs normal?