Re: [zfs-discuss] How much do we really want zpool remove?
On Thu, Jan 18, 2007 at 06:55:39PM +0800, Jeremy Teo wrote: > On the issue of the ability to remove a device from a zpool, how > useful/pressing is this feature? Or is this more along the line of > "nice to have"? We definitely need it. As a usage case, on occasion we have had to move SAN sites, and the easiest way to that by far is to snap on the new site and remove the old one once it's synced. Ceri -- That must be wonderful! I don't understand it at all. -- Moliere pgpFK45y3OxA6.pgp Description: PGP signature ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re[2]: [zfs-discuss] How much do we really want zpool remove?
Hello Matthew, Thursday, January 18, 2007, 7:51:18 PM, you wrote: MA> Jeremy Teo wrote: >> On the issue of the ability to remove a device from a zpool, how >> useful/pressing is this feature? Or is this more along the line of >> "nice to have"? MA> This is a pretty high priority. We are working on it. Quick, precise and "informative". Ok, can you give us any details? Like only removal or also adding a disk and re-writing all data to much new stripe width? Also conversion Z1<->Z2? Other also (10->Z1, ...)? Any estimate when and what would hit ON? -- Best regards, Robertmailto:[EMAIL PROTECTED] http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re[2]: [zfs-discuss] How much do we really want zpool remove?
Hello mike, Friday, January 19, 2007, 4:07:31 AM, you wrote: m> I get that part. I think I asked that question before (although not as m> direct) - basically you're talking about the ability to shrink volumes m> and/or disable/change the mirroring/redundancy options if there is m> space available to account for it. You can already convert RAID-10 to RAID-0 and vice versa with ZFS. Just attach/detach disks. m> If this was allowed, this would also allow for a conversion from RAIDZ m> to RAIDZ2, or vice-versa then, correct? Not really - at least not directly. -- Best regards, Robertmailto:[EMAIL PROTECTED] http://milek.blogspot.com ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
I get that part. I think I asked that question before (although not as direct) - basically you're talking about the ability to shrink volumes and/or disable/change the mirroring/redundancy options if there is space available to account for it. If this was allowed, this would also allow for a conversion from RAIDZ to RAIDZ2, or vice-versa then, correct? On 1/18/07, Erik Trimble <[EMAIL PROTECTED]> wrote: Mike, I think you are missing the point. What we are talking about is removing a drive from a zpool, that is, reducing the zpool's total capacity by a drive. Say you have 4 drives of 100GB in size, configured in a striped mirror, capacity of 200GB usable. We're discussing the case where if the zpool's total used space is under 100GB, we could remove the second vdev (consisting of a mirror) from the zpool, and have ZFS evacuate all the data from the to-be-removed vdev before we actually remove the disks (or, maybe we simply want to reconfigure them into another zpool). In this case, after the drive remoovals, the zpool would be left with a 100GB capacity, and be a simple 2-drive mirror. What you are talking about is replacement of a drive, whether or not it is actually bad. In your instance, the zpool capacity size remains the same, and it will return to optimal performance when a new drive is inserted (and, no, there is no difference between a manual and automatic "removal" in the case of marking a drive bad for replacement). -Erik ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
Mike, I think you are missing the point. What we are talking about is removing a drive from a zpool, that is, reducing the zpool's total capacity by a drive. Say you have 4 drives of 100GB in size, configured in a striped mirror, capacity of 200GB usable. We're discussing the case where if the zpool's total used space is under 100GB, we could remove the second vdev (consisting of a mirror) from the zpool, and have ZFS evacuate all the data from the to-be-removed vdev before we actually remove the disks (or, maybe we simply want to reconfigure them into another zpool). In this case, after the drive remoovals, the zpool would be left with a 100GB capacity, and be a simple 2-drive mirror. What you are talking about is replacement of a drive, whether or not it is actually bad. In your instance, the zpool capacity size remains the same, and it will return to optimal performance when a new drive is inserted (and, no, there is no difference between a manual and automatic "removal" in the case of marking a drive bad for replacement). -Erik On Thu, 2007-01-18 at 18:01 -0800, mike wrote: > what is the technical difference between forcing a removal and an > actual failure? > > isn't it the same process? except one is manually triggered? i would > assume the same resilvering process happens when a usable drive is put > back in... > > On 1/18/07, Wee Yeh Tan <[EMAIL PROTECTED]> wrote: > > Not quite. I suspect you are thinking about drive replacement rather > > than removal. > > > > Drive replacement is already supported in ZFS and the task involves > > rebuilding data on the disk from data available elsewhere. Drive > > removal involves rebalancing data from the target drive to other > > disks. The latter is non-trivial. > > > > > > -- > > Just me, > > Wire ... > > > ___ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss -- Erik Trimble Java System Support Mailstop: usca14-102 Phone: x17195 Santa Clara, CA Timezone: US/Pacific (GMT-0800) ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
what is the technical difference between forcing a removal and an actual failure? isn't it the same process? except one is manually triggered? i would assume the same resilvering process happens when a usable drive is put back in... On 1/18/07, Wee Yeh Tan <[EMAIL PROTECTED]> wrote: Not quite. I suspect you are thinking about drive replacement rather than removal. Drive replacement is already supported in ZFS and the task involves rebuilding data on the disk from data available elsewhere. Drive removal involves rebalancing data from the target drive to other disks. The latter is non-trivial. -- Just me, Wire ... ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
On 1/19/07, mike <[EMAIL PROTECTED]> wrote: Would this be the same as failing a drive on purpose to remove it? I was under the impression that was supported, but I wasn't sure if shrinking a ZFS pool would work though. Not quite. I suspect you are thinking about drive replacement rather than removal. Drive replacement is already supported in ZFS and the task involves rebuilding data on the disk from data available elsewhere. Drive removal involves rebalancing data from the target drive to other disks. The latter is non-trivial. -- Just me, Wire ... ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
Would this be the same as failing a drive on purpose to remove it? I was under the impression that was supported, but I wasn't sure if shrinking a ZFS pool would work though. On 1/18/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > This is a pretty high priority. We are working on it. ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
[EMAIL PROTECTED] wrote on 01/18/2007 01:29:23 PM: > On Thu, 2007-01-18 at 10:51 -0800, Matthew Ahrens wrote: > > Jeremy Teo wrote: > > > On the issue of the ability to remove a device from a zpool, how > > > useful/pressing is this feature? Or is this more along the line of > > > "nice to have"? > > > > This is a pretty high priority. We are working on it. > > > > --matt > > I'd consider it a lower priority than say, adding a drive to a RAIDZ > vdev, but yes, being able to reduce a zpool's size by removing devices > is quite useful, as it adds a considerable degree of flexibility that > (we) admins crave. > I would be surprised if much of the code to allow removal does not bring device adds closer to reality -- assuming device removal migrates data and resilvers to optimal stripe online.. -Wade ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
On Thu, 2007-01-18 at 10:51 -0800, Matthew Ahrens wrote: > Jeremy Teo wrote: > > On the issue of the ability to remove a device from a zpool, how > > useful/pressing is this feature? Or is this more along the line of > > "nice to have"? > > This is a pretty high priority. We are working on it. > > --matt I'd consider it a lower priority than say, adding a drive to a RAIDZ vdev, but yes, being able to reduce a zpool's size by removing devices is quite useful, as it adds a considerable degree of flexibility that (we) admins crave. -- Erik Trimble Java System Support Mailstop: usca14-102 Phone: x17195 Santa Clara, CA Timezone: US/Pacific (GMT-0800) ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
Jeremy Teo wrote: On the issue of the ability to remove a device from a zpool, how useful/pressing is this feature? Or is this more along the line of "nice to have"? This is a pretty high priority. We are working on it. --matt ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
On 18/01/2007, at 9:55 PM, Jeremy Teo wrote: On the issue of the ability to remove a device from a zpool, how useful/pressing is this feature? Or is this more along the line of "nice to have"? Assuming we're talking about removing a top-level vdev.. I introduce new sysadmins to ZFS on a weekly basis. After 2 hours of introduction this is the single feature that they most often realise is "missing". The most common reason is migration of data to new storage infrastructure. The experience is often that the growth in disk size allows the new storage to consist of fewer disks/LUNs than the old. I can see that is will come increasingly needed as more and more storage goes under ZFS. Sure, we can put 256 quadrillion zettabytes in the pool, but if you accidentally add a disk to the wrong pool or with the wrong redundancy you have a long long wait for your tape drive :) Boyd ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
On 18/01/07, Jeremy Teo <[EMAIL PROTECTED]> wrote: On the issue of the ability to remove a device from a zpool, how useful/pressing is this feature? Or is this more along the line of "nice to have"? It's very useful if you accidentally create a concat rather than mirror of an existing zpool. Otherwise you have to buy another drive :) -- Rasputin :: Jack of All Trades - Master of Nuns http://number9.hellooperator.net/ ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] How much do we really want zpool remove?
On Thu, Jan 18, 2007 at 06:55:39PM +0800, Jeremy Teo wrote: > On the issue of the ability to remove a device from a zpool, how > useful/pressing is this feature? Or is this more along the line of > "nice to have"? If you think "remove a device from a zpool" = "to shrink a pool" then it is really usefull. Definitely really usefull. Do you need any example ? przemol -- Lufa dla generala. Zobacz >> http://link.interia.pl/f19e1 ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
[zfs-discuss] How much do we really want zpool remove?
On the issue of the ability to remove a device from a zpool, how useful/pressing is this feature? Or is this more along the line of "nice to have"? -- Regards, Jeremy ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
