Hi, I am from Linux world, and looking to see if opensolaris/zfs would be a nice combination for an iSCSI target. I am reading up various docs about zfs now. What I have now is iSCSI exporting a 11 disk RAID5 array. I want to move it to zfs. What I am really looking for is to see if: 1. iSCSI target support (obviously) 2. How tolerant is zfs towards disk failures. ie I suppose raidz can overcome one disk failure, any thing more? also in a normal RAID5 if another disk fails while the array is reconstructing that RAID5 is gone. How about this in raidz? Is there a long reconstruction phase? 3. How to expand the array. ie if I have 3x400G disk right now, can I add another one more drive and"grow" the array ? I am totally blown away by zfs, and as some one who is maintaining some critical RAID5 arrays, this will let me sleep more peacefully :) warm regards, raj
ZFS would be an excellent choice for an iSCSI target, for at least three reasons. * It has very good data integrity characteristics (always nice for a storage subsystem!). * It can efficiently process small I/O operations (the bulk of what disks typically see). * Its transactional semantics keep the target always consistent. It would be possible to port existing iSCSI target code to Solaris and have it use either a ZFS file or volume (zvol) as the backing store. (Typically the target code is not tied to a particular file system or volume.) Solaris currently ships with iSCSI initiator support but not target support. Target support may be in its future; see http://blogs.sun.com/roller/page/torrey?entry=that_solaris_iscsi_target ... This message posted from opensolaris.org
If you haven''t yet, check out Jeff Bonwick''s blog on RAID-Z. In it he talks about some of the capabilities and bonuses of RAID-Z as compared to conventional RAID 5. In addition, he explains how reconstruction is done and disks are repaired in case of corruption and other sorts of interesting goodness. http://blogs.sun.com/roller/page/bonwick?entry=raid_z As far as expanding RAID-Z, you cannot expand a RAID-Z stripe, it''s a fixed width stripe. You can find out more information from the discussion here: http://www.opensolaris.org/jive/thread.jspa?messageID=15219㭳 Noel :-) ************************************************************************ ** "Question all the answers" On Dec 7, 2005, at 12:31 PM, Rajkumar S wrote:> Hi, > > I am from Linux world, and looking to see if opensolaris/zfs would be > a nice combination for an iSCSI target. I am reading up various docs > about zfs now. What I have now is iSCSI exporting a 11 disk RAID5 > array. I want to move it to zfs. What I am really looking for is to > see if: > > 1. iSCSI target support (obviously) > > 2. How tolerant is zfs towards disk failures. ie I suppose raidz can > overcome one disk failure, any thing more? also in a normal RAID5 if > another disk fails while the array is reconstructing that RAID5 is > gone. How about this in raidz? Is there a long reconstruction phase? > > 3. How to expand the array. ie if I have 3x400G disk right now, can I > add another one more drive and"grow" the array ? > > I am totally blown away by zfs, and as some one who is maintaining > some critical RAID5 arrays, this will let me sleep more peacefully :) > > warm regards, > > raj > _______________________________________________ > zfs-discuss mailing list > zfs-discuss at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Hi all, Bumping this thread up. Looking for some information about the status of an iSCSI target for OpenSolaris. raj> Hi, > > I am from Linux world, and looking to see if > opensolaris/zfs would be > a nice combination for an iSCSI target. I am reading > up various docs > about zfs now. What I have now is iSCSI exporting a > 11 disk RAID5 > array. I want to move it to zfs. What I am really > looking for is to > see if: > > 1. iSCSI target support (obviously) > > 2. How tolerant is zfs towards disk failures. ie I > suppose raidz can > overcome one disk failure, any thing more? also in a > normal RAID5 if > another disk fails while the array is reconstructing > that RAID5 is > gone. How about this in raidz? Is there a long > reconstruction phase? > > 3. How to expand the array. ie if I have 3x400G disk > right now, can I > add another one more drive and"grow" the array ? > > I am totally blown away by zfs, and as some one who > is maintaining > some critical RAID5 arrays, this will let me sleep > more peacefully :) > > warm regards, > > rajThis message posted from opensolaris.org
Rajkumar S wrote:> I am from Linux world, and looking to see if opensolaris/zfs> would be a nice combination for an iSCSI target. I am reading> up various docs about zfs now. What I have now is iSCSI> exporting a 11 disk RAID5 array. I want to move it to zfs. > What I am really looking for is to see if:> > 1. iSCSI target support (obviously)Solaris 10 update 1, and current builds of Solaris Express. See http://www.sun.com/io_technologies/iSCSI.html and http://blogs.sun.com/roller/page/dweibel for more. David is the iSCSI lead engineer.> 2. How tolerant is zfs towards disk failures. ie I > suppose raidz can overcome one disk failure, any thing > more? also in a normal RAID5 if another disk fails> while the array is reconstructing that RAID5 is gone. > How about this in raidz? Is there a long reconstruction > phase? Jeff Bonwick''s blog goes into detail on raid-Z. As for reconstruction.... not sure. I think it''ll depend on how much data you need to re-silver. http://blogs.sun.com/bonwick will have more, and pointers to other relevant sources.> 3. How to expand the array. ie if I have 3x400G disk > right now, can I add another one more drive and "grow" > the array ?sure # zpool add <name_of_pool> <device> eg # zpool add multipack1 c1t2d0 and have a nice day. The new device is used straight away. There''s a whole heap more in the manpages for zpool(1M) and zfs(1M). An important thing to remember is that the amount of available documentation is in *inverse* proportion to the power of zfs.> I am totally blown away by zfs, and as some one who > is maintaining some critical RAID5 arrays, this will> let me sleep more peacefully :) Excellent! The more drudgery we take out of the system admin role the more enjoyable your (and our!) life gets. As an aside, it would be of value to the zfs, storage and OpenSolaris communities for you to post an account of your experiences with zfs and iSCSI -- the more info that we have to share, the better it is for all of us. best regards, James C. McPherson -- Solaris Datapath Engineering Data Management Group Sun Microsystems
James C. McPherson wrote:> Rajkumar S wrote: >> I am from Linux world, and looking to see if opensolaris/zfs > > would be a nice combination for an iSCSI target. I am reading >> up various docs about zfs now. What I have now is iSCSI > > exporting a 11 disk RAID5 array. I want to move it to zfs. > > What I am really looking for is to see if: >> >> 1. iSCSI target support (obviously) > > Solaris 10 update 1, and current builds of Solaris Express. > See http://www.sun.com/io_technologies/iSCSI.html and > http://blogs.sun.com/roller/page/dweibel for more. David > is the iSCSI lead engineer. >Not to try and confuse things here but iare you looking for a iSCSI software stack that runs on Solaris and allows for the use of iSCSI enabled storage arrays from that node or Are you looking for iSCSI target software that runs on Solaris and allows you to export devices over the iSCSI protocol to other nodes?
On Fri, Feb 24, 2006 at 07:13:31PM +1100, James C. McPherson wrote:> Rajkumar S wrote: > >1. iSCSI target support (obviously) > > Solaris 10 update 1, and current builds of Solaris Express. > See http://www.sun.com/io_technologies/iSCSI.html and > http://blogs.sun.com/roller/page/dweibel for more. David > is the iSCSI lead engineer.Actually, that''s the iSCSI initiator. Target mode support is coming; sooner rather than later.> >3. How to expand the array. ie if I have 3x400G disk > >right now, can I add another one more drive and "grow" > >the array ? > > sure > > # zpool add <name_of_pool> <device> > > eg > > # zpool add multipack1 c1t2d0 > > and have a nice day. The new device is used straight > away.That will work, but what you''ll wind up with is a 3-disk RAID-Z array, plus a single, unreplicated disk. Probably not what you want. The ability to dynamically grow RAID-Z will not be in the first version of ZFS, but we are working on it, since it''s so darn useful. --Bill
On 2/24/06, Bill Moore <Bill.Moore at sun.com> wrote:> On Fri, Feb 24, 2006 at 07:13:31PM +1100, James C. McPherson wrote: > > Rajkumar S wrote: > > >1. iSCSI target support (obviously)> Actually, that''s the iSCSI initiator. Target mode support is > coming; sooner rather than later./me waiting for it. :) raid-z would make an excellent target because of it''s excellent data integrity properties. While an iscsi initiator is a nice feature, I am sure I will not be able to use all checksum and other integrity features unless the whole data path down to the hard disk is under solaris (opposed to having an zfs file system on raid-5 exported via iSCSI)> The ability to dynamically grow RAID-Z > will not be in the first version of ZFS, but we are working > on it, since it''s so darn useful.Thanks! raj