On 1/21/07, Liang Yang <multisyncfe991@xxxxxxxxxxx> wrote:
Hello, I have tried to increase the Striped_Cache_Size from 256 (default for my MD-RAID5 array) to 8192, it does improve the MD-RAID5 Write performance which varies with the size of I/O packet. However, I'm still not very clean the meaning and the potential performance impact of this Striped_Cache_Size? Is the unit for this parameter Byte or KiloByte? Could anyone here explain with a little bit more details?
stripe_cache_size is the number of stripes in the cache. Each stripe (strip) is composed one PAGE_SIZE block per disk. If your page size is 4k and you have 4 disks in your array then a stripe_cache_size of 256 is 4k * 4 * 256 = 4MB. Increasing this number increases the chances that a write to the array will not generate reads to satisfy the parity calculation.
Thanks, Liang
Regards, Dan - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
