22.01.2013 22:29, Oleksii Tsvietnov пишет: > >> graid3 нельзя использовать без gcache. > > from man gcache: > "thus effectively killing disk performance under high load." > > Да, так и произошло... ;)) > На сколько gcache сделает возможным использование graid3 на high load? > Есть какие-то субъективные ощущения по сравнению с ZFS zpool по скорости?
У меня нет ZFS, так что сравнивать не с чем. И про RAID3 вообще (безотносительно конкретной реализации) википедия говорит: RAID 3 is very rare in practice. One of the characteristics of RAID 3 is that it generally cannot service multiple requests simultaneously. This happens because any single block of data will, by definition, be spread across all members of the set and will reside in the same location. So, any I/O operation requires activity on every disk and usually requires synchronized spindles. [skip] The performance of the array is therefore identical to the performance of one disk in the array except for the transfer rate, which is multiplied by the number of data drives less the parity drives. [skip] This makes it best for applications that demand the highest transfer rates in long sequential reads and writes, for example uncompressed video editing. Applications that make small reads and writes from random disk locations will get the worst performance out of this level.
