From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: Mdadm, udev and fakeraid? Date: Mon, 18 Apr 2011 10:38:52 +1000 Message-ID: <20110418103852.2ead1a69@notabene.brown> References: <20110405162008.5f2c48fe@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Seblu Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Fri, 15 Apr 2011 16:15:50 +0200 Seblu wrote: > On Tue, Apr 5, 2011 at 8:20 AM, NeilBrown wrote: > > On Sun, 3 Apr 2011 18:03:50 +0200 Seblu 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=3Dmdadm;a=3Dcommit;h=3D475a01b8bce857= 5dd1b2ab6495e65e854702ac0e > >> > >> 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 no= t sure > > what you are asking. >=20 > Hello Neil, >=20 > 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. >=20 > So my question was about compatibily. Raids created by dmraid can be > assembled with mdadm and vice versa? >=20 > > Both dmraid and mdadm can manage some 'fakeraid' arrays. =A0dmraid = supports a > > wider variety. =A0mdadm supports raid1 and raid5 more completely th= an dmraid > > does. > mdadm -> create soft raid for linux (now there is new format: ddf an= d 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 ve= ry well. mdadm supports both of these well, but doesn't support the same range o= f "industry raid card formats". There is a growing amount of overlap. >=20 > > Both should support isw to some degree. > > Intel are currently working with mdadm to make it provide full supp= ort for > > "IMSM" (Intel Matrix Storage Manager). =A0I don't know the exact re= lationship > > between 'isw' and 'IMSM' - maybe they are different names for the s= ame thing. > ok >=20 > > 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). >=20 > 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. >=20 > 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=3D"isw_raid_member" > and on "mdadm" created raid: > /dev/sdd: UUID=3D"a974b525-993a-1481-f860-6471f3f120e1" > UUID_SUB=3D"eb22aee2-b2ee-e56d-1008-44d52c63564d" LABEL=3D"archipel:0= " > TYPE=3D"linux_raid_member" >=20 > 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. >=20 > About outputs: > mdadm -I --verbose /dev/sde > mdadm: no RAID superblock on /dev/sde. 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. >=20 > # mdadm --examine /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 >=20 > Disk00 Serial : 66faec8-9f5b237d > State : active > Id : 00040000 > Usable Size : 1019486 (497.88 MiB 521.98 MB) >=20 > [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 >=20 > Disk01 Serial : 0b540c6-4e527908 > State : active > Id : 00050000 > Usable Size : 1019486 (497.88 MiB 521.98 MB) >=20 >=20 > Do not you think that dmraid should also ship an udev rules file to > mount the raid which can handle? I have no opinion about what dmraid should do. I have enough trouble w= orking out what mdadm should do :-) NeilBrown >=20 > Regards, >=20 -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html