storage

Align Your Partitions

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This is post #1 in my December-long series on Linux VM performance tuning, Tuningmas. I wrote about it back in 2006, and lots of others have written about it since (Duncan Epping has a nice vendor-agnostic post with diagrams): misaligned storage trashing your I/O performance. What’s the big deal? In short, it is killing your I/O performance. Logical Block Addressing on your disk drive makes the Master Boot Record 63 bytes long. This means it occupies sectors 0-62 on disk, and the first partition will start at sector 63. The number 63 is a persona non grata in the computer world. It isn’t a power of 2, and it certainly doesn’t line up with your storage’s idea of the world …

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Dell, SSD, CacheCade, and H700/H800 Controllers

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Dell’s announcement last week that their rebranded LSI RAID controllers, the H700 & H800, now have the ability to use certain local SSD disks as a read cache tier. This is the “CacheCade” technology LSI has offered since September 2010, and looks functionally similar to technologies like NetApp’s FlashCache, where SSD maintains a copy of “hot” blocks on the fast storage. There are some limitations to it, namely that it will require the H700/H800 models with 1 GB of NVRAM on them, and comes as part of a certain firmware level. The feature will also only work with certain SSDs from Dell, so you can’t plan to just cram a cheap Intel X-25 in there (which is unfortunate, in my …

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