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Top Forums Programming Tool to simulate non-sequential disk I/O (simulate db file sequential read) in C POSIX Post 302531355 by Corona688 on Thursday 16th of June 2011 01:15:54 PM
Old 06-16-2011
No problem.

Unless you've got SSD's, disks are atrocious for random read in general. Reading sequential disk blocks(512 bytes) you can get 100+MB per second on a modern disk. Reading random blocks from that same modern disk, assuming a 15ms seek time, you get worst-case transfer rates in double-digit kilobytes per second. Until SSD's started becoming practical the usual way to overcome this was gigantic amounts of cache.
 

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volreattach(8)						      System Manager's Manual						    volreattach(8)

NAME
volreattach - Reattaches disk drives that have once again become accessible SYNOPSIS
/usr/sbin/volreattach [-rb] [accessname...] /usr/sbin/volreattach -c accessname OPTIONS
The volreattach utility has the following options: Calls the volrecover utility to attempt to recover stale plexes of any volumes on the failed disk. Performs the reattach operation in the background. Checks whether a reattach is possible. No operation is performed, but the name of the disk group and disk media name at which the disk can be reattached is displayed. DESCRIPTION
The volreattach utility attempts to reattach disks using the same disk group and media names they had before detachment. This operation may be necessary if a disk has a transient failure, or if some disk drivers are unloaded or unloadable when the Logical Storage Manager is started, causing disks to enter the failed state. If the problem is fixed, the volreattach command can be used to reattach the disks without plexes being flagged as stale, as long as the reattach happens before any volumes on the disk are started. The volreattach command is called from the voldiskadm menus as part of disk recovery. The volreattach utility tries to find a disk with a disk group and disk ID matching that of the disk(s) being reattached. If the matching disk is found, the reattach operation may still fail if the original cause (or some other cause) for the disk failure still exists. EXIT CODES
A zero exit status is returned if it is possible to perform a reattach. Otherwise, non-zero is returned. SEE ALSO
volintro(8), voldiskadm(8), volrecover(8) volreattach(8)
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