On 08/05/2017 05:51 PM, Shaohua Li wrote: > From: Shaohua Li <shli@xxxxxx> > > In testing software RAID, I usually found it's hard to cover specific cases. > RAID is supposed to work even disk is in semi good state, for example, some > sectors are broken. Since we can't control the behavior of hardware, it's > difficult to create test suites to do destructive tests. But we can control the > behavior of software, software based disk is an obvious choice for such tests. > While we already have several software based disks for testing (eg, null_blk, > scsi_debug), none is for destructive testing, this is the reason we create a > new test block device. > > Currently the driver can create disk with following features: > - Bandwidth control. A raid array consists of several disks. The disks could > run in different speed, for example, one disk is SSD and the other is HD. > Actually raid1 has a feature called write behind just for this. To test such > raid1 feature, we'd like the disks speed could be controlled. > - Emulate disk cache. Software must flush disk cache to guarantee data is > safely stored in media after a power failure. To verify if software works > well, we can't simply use physical disk, because even software doesn't flush > cache, the hardware probably will flush the cache. With a software > implementation of disk cache, we can fully control how we flush disk cache in a > power failure. > - Badblock. If only part of a disk is broken, software raid continues working. > To test if software raid works well, disks must include some broken parts or > bad blocks. Bad blocks can be easily implemented in software. > > While this is inspired by software raid testing, the driver is very flexible > for extension. We can easily add new features into the driver. The interface is > configfs, which can be configured with a shell script. There is a 'features' > attribute exposing all supported features. By checking this, we don't need to > worry about compability issues. For configuration details, please check the > first patch. > Any particular reason why you can't fold these changes into brd or null_blk? After all, without those testing features it is 'just' another ramdisk driver... > This is William's intern project. I made some changes, all errors are mine. You > are more than welcomed to test and add new features! > Ah. But then why isn't he mentioned in the From: or Signed-off: lines? Shouldn't he be getting some more credits than just 'William'? (Unless William is in fact an alias for Kyungchan Koh, in which case a name mapping would be nice ...) Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)
