1*d3c7b35cSHeinz Mauelshagen====== 2*d3c7b35cSHeinz Mauelshagendm-ebs 3*d3c7b35cSHeinz Mauelshagen====== 4*d3c7b35cSHeinz Mauelshagen 5*d3c7b35cSHeinz Mauelshagen 6*d3c7b35cSHeinz MauelshagenThis target is similar to the linear target except that it emulates 7*d3c7b35cSHeinz Mauelshagena smaller logical block size on a device with a larger logical block 8*d3c7b35cSHeinz Mauelshagensize. Its main purpose is to provide emulation of 512 byte sectors on 9*d3c7b35cSHeinz Mauelshagendevices that do not provide this emulation (i.e. 4K native disks). 10*d3c7b35cSHeinz Mauelshagen 11*d3c7b35cSHeinz MauelshagenSupported emulated logical block sizes 512, 1024, 2048 and 4096. 12*d3c7b35cSHeinz Mauelshagen 13*d3c7b35cSHeinz MauelshagenUnderlying block size can be set to > 4K to test buffering larger units. 14*d3c7b35cSHeinz Mauelshagen 15*d3c7b35cSHeinz Mauelshagen 16*d3c7b35cSHeinz MauelshagenTable parameters 17*d3c7b35cSHeinz Mauelshagen---------------- 18*d3c7b35cSHeinz Mauelshagen <dev path> <offset> <emulated sectors> [<underlying sectors>] 19*d3c7b35cSHeinz Mauelshagen 20*d3c7b35cSHeinz MauelshagenMandatory parameters: 21*d3c7b35cSHeinz Mauelshagen 22*d3c7b35cSHeinz Mauelshagen <dev path>: 23*d3c7b35cSHeinz Mauelshagen Full pathname to the underlying block-device, 24*d3c7b35cSHeinz Mauelshagen or a "major:minor" device-number. 25*d3c7b35cSHeinz Mauelshagen <offset>: 26*d3c7b35cSHeinz Mauelshagen Starting sector within the device; 27*d3c7b35cSHeinz Mauelshagen has to be a multiple of <emulated sectors>. 28*d3c7b35cSHeinz Mauelshagen <emulated sectors>: 29*d3c7b35cSHeinz Mauelshagen Number of sectors defining the logical block size to be emulated; 30*d3c7b35cSHeinz Mauelshagen 1, 2, 4, 8 sectors of 512 bytes supported. 31*d3c7b35cSHeinz Mauelshagen 32*d3c7b35cSHeinz MauelshagenOptional parameter: 33*d3c7b35cSHeinz Mauelshagen 34*d3c7b35cSHeinz Mauelshagen <underyling sectors>: 35*d3c7b35cSHeinz Mauelshagen Number of sectors defining the logical block size of <dev path>. 36*d3c7b35cSHeinz Mauelshagen 2^N supported, e.g. 8 = emulate 8 sectors of 512 bytes = 4KiB. 37*d3c7b35cSHeinz Mauelshagen If not provided, the logical block size of <dev path> will be used. 38*d3c7b35cSHeinz Mauelshagen 39*d3c7b35cSHeinz Mauelshagen 40*d3c7b35cSHeinz MauelshagenExamples: 41*d3c7b35cSHeinz Mauelshagen 42*d3c7b35cSHeinz MauelshagenEmulate 1 sector = 512 bytes logical block size on /dev/sda starting at 43*d3c7b35cSHeinz Mauelshagenoffset 1024 sectors with underlying devices block size automatically set: 44*d3c7b35cSHeinz Mauelshagen 45*d3c7b35cSHeinz Mauelshagenebs /dev/sda 1024 1 46*d3c7b35cSHeinz Mauelshagen 47*d3c7b35cSHeinz MauelshagenEmulate 2 sector = 1KiB logical block size on /dev/sda starting at 48*d3c7b35cSHeinz Mauelshagenoffset 128 sectors, enforce 2KiB underlying device block size. 49*d3c7b35cSHeinz MauelshagenThis presumes 2KiB logical blocksize on /dev/sda or less to work: 50*d3c7b35cSHeinz Mauelshagen 51*d3c7b35cSHeinz Mauelshagenebs /dev/sda 128 2 4 52