On Sat, Apr 23, 2011 at 4:37 AM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > On Sun, Apr 17, 2011 at 5:38 PM, NeilBrown <neilb@xxxxxxx> wrote: >> On Fri, 15 Apr 2011 16:15:50 +0200 Seblu <seblu@xxxxxxxxx> wrote: >> >>> On Tue, Apr 5, 2011 at 8:20 AM, NeilBrown <neilb@xxxxxxx> wrote: >>> > On Sun, 3 Apr 2011 18:03:50 +0200 Seblu <seblu@xxxxxxxxx> wrote: >>> > >>> >> Hello, >>> >> >>> >> In the following commit, udev rules load isw_raid (fakeraid). From my >>> >> test, this doesnt work. I have to call dmraid to have something >>> >> working. >>> >> http://neil.brown.name/git?p=mdadm;a=commit;h=475a01b8bce8575dd1b2ab6495e65e854702ac0e >>> >> >>> >> isw_raid is only fakeraid devices? mdadm is able to mount fakeraid partition? >>> >> >>> > >>> > I'm sorry but I cannot parse those questions successfully so I'm not sure >>> > what you are asking. >>> >>> Hello Neil, >>> >>> in my previous mail, i used word fakeraid about raid created with >>> dmraid and i used softraid about raid created with mdadm. it was not >>> clear. >>> >>> So my question was about compatibily. Raids created by dmraid can be >>> assembled with mdadm and vice versa? >>> >>> > Both dmraid and mdadm can manage some 'fakeraid' arrays. dmraid supports a >>> > wider variety. mdadm supports raid1 and raid5 more completely than dmraid >>> > does. >>> mdadm -> create soft raid for linux (now there is new format: ddf and imsm) ? >>> dmraid -> create soft raid from industry raid card format ? >> >> No, it isn't that simple. >> >> dmraid uses the 'dm' kernel module. mdadm uses the 'md' kernel module. >> >> As such dmraid doesn't support RAID5 (yet) and doesn't support RAID1 very >> well. >> mdadm supports both of these well, but doesn't support the same range of >> "industry raid card formats". >> >> There is a growing amount of overlap. >> >>> >>> > Both should support isw to some degree. >>> > Intel are currently working with mdadm to make it provide full support for >>> > "IMSM" (Intel Matrix Storage Manager). I don't know the exact relationship >>> > between 'isw' and 'IMSM' - maybe they are different names for the same thing. >>> ok >>> >>> > If mdadm doesn't work for your isw arrays, and you want it to, then I suggest >>> > you report details about what is, or is not, happening. >>> My purpose is to improve archlinux startup detection of fakeraids >>> (mdadm + dmraid). >>> >>> With mdadm everything works correctly without call to "mdadm -As" >>> With dmraid, no raid is created by udev rules, so we need to run >>> "dmraid -i -ay" at startup. >>> >>> To test this kind of raid, i created a dmraid array in a vm. This >>> created me a /dev/mapper/isw_bfbjdbadhb_testF device. >>> call blkid on a disk member of this raid tell me this: >>> /dev/sde: TYPE="isw_raid_member" >>> and on "mdadm" created raid: >>> /dev/sdd: UUID="a974b525-993a-1481-f860-6471f3f120e1" >>> UUID_SUB="eb22aee2-b2ee-e56d-1008-44d52c63564d" LABEL="archipel:0" >>> TYPE="linux_raid_member" >>> >>> This misled me because mdadm udev rules uses the output of blkid to >>> mount raids which have type "isw_raid_member". >>> What disturbs me is that mdadm cannot mount raid created by dmraid >>> with type isw_raid_member. >>> >>> About outputs: >>> mdadm -I --verbose /dev/sde >>> mdadm: no RAID superblock on /dev/sde. > > Seblu can you verify that: > export IMSM_NO_PLATFORM=1 > mdadm -E /dev/sde archipel ~ 0 # export IMSM_NO_PLATFORM=1 archipel ~ 1 # mdadm -E /dev/sde /dev/sde: Magic : Intel Raid ISM Cfg Sig. Version : 1.1.00 Orig Family : 5a8ed623 Family : 5a8ed623 Generation : 00000000 UUID : ae2e9cd8:7fa43248:47c694a1:24990cbc Checksum : c23b6c88 correct MPB Sectors : 1 Disks : 2 RAID Devices : 1 Disk00 Serial : 66faec8-9f5b237d State : active Id : 00040000 Usable Size : 1019486 (497.88 MiB 521.98 MB) [testF]: UUID : 6640a4cc:5faa1ce3:c1bff2b3:1093ca7d RAID Level : 1 Members : 2 Slots : [UU] Failed disk : none This Slot : 0 Array Size : 1014446 (495.42 MiB 519.40 MB) Per Dev Size : 1014792 (495.59 MiB 519.57 MB) Sector Offset : 0 Num Stripes : 3963 Chunk Size : 64 KiB Reserved : 0 Migrate State : idle Map State : normal Dirty State : clean Disk01 Serial : 0b540c6-4e527908 State : active Id : 00050000 Usable Size : 1019486 (497.88 MiB 521.98 MB) > > finds no superblock? It may be that dmraid has laid down something incompatible. > >> As has been mentioned elsewhere, mdadm only recognised IMSM arrays on >> machines with IMSM hardware. I'm not entirely happy about this and may well >> change it. > > I have trouble answering the "least surprise" question in this area. > > Is it more surprising to go into your BIOS, explicitly turn off raid > support and still see raid devices showing up? > > Or is it more surprising to take a raid array from a raid enabled > system to raid disabled system and wonder why things won't assemble? > > For safety I think it is better if mdadm not perform operations that > might be incompatible with the platform option-rom. But if you need > to recover to a usb attached drive, or some other > platform-incompatible configuration, you can use the environment > variable in a pinch. > > -- > Dan > -- Sébastien Luttringer www.seblu.net -- 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
