Re: zfs: 9 vs current, and ZIL/L2ARC on ssd?
hello Greg. Zfs seems to be much more stable in -current than 9.x. In particular, if you're using xen, then you definitely want -current because ZFS and xen under 9.x use different maxphys values for data transfers, which leads to a lot of corruption and crashes when using zfs as backingstore for xen domains. Also, under -current, dom0 can be a multi-vcpu system, which should help performance significantly when it comes to i/o on the domu's, especially if running any kind of hvm or pvh domain. Hope that helps. -thanks -Brian On Feb 11, 1:17pm, Greg Troxel wrote: } Subject: zfs: 9 vs current, and ZIL/L2ARC on ssd? } --=-=-= } Content-Type: text/plain } } } I am about to try to use zfs for the first time and have a few } questions. } } I have a machine that is running NetBSD-9/amd64 with 2 cores, 8G of RAM, } a single 1T SSD, with a smallish root/swap/usr, and about 870 GiB free } intended for zfs. I am heading for one po0l that is not raid at all. } } I'm not all that worried about transitions or stability; this is a build } machine for packages, not particularly precious, and it being down for a } week while I fix it is no big deal. } } I will likely pivot the machine to be xen dom0; I hope that doesn't } matter much (other than 1 core only in the dom0). Or I might use nvmm, } or both. } } I might add a spinning disk later, either internal or USB. (I realize } that there, I probably want both ZIL and L2ARC on SSD. I would rather } move bits later than do things now to ease that, since I do not have an } actual plan.) } } My questions are: } } Is 9/current close enough to the same zfs code that it doesn't matter } which I run? If I'm inclined to run current for other reasons, is } that a bad idea zfs-wise? } } I understand that zfs has an intent log always, and that can be within } the pool, or one can add a ZIL device. With the pool having one } device which is an SSD, I see no point in partitioning off part of } that SSD to be the ZIL. } } I understand that zfs has ARC in RAM, and can have L2ARC on disk. } Given that the pool is on SSD, it seems pointless to split off some } for L2ARC. } } My expected answers are: } } The code is basically the same and it doesn't really matter but } probably current has some bugfixes 9 doesn't. There's no reason } current is scary becuase of zfs. } } There is no point in a ZIL on the same SSD as the pool. } } There is really no point in L2ARC on the same SSD as the pool. } } } Corrections/clues appreciated. }
Re: zfs: 9 vs current, and ZIL/L2ARC on ssd?
On Thu, 11 Feb 2021 at 18:17, Greg Troxel wrote: > > > I am about to try to use zfs for the first time and have a few > questions. > > I have a machine that is running NetBSD-9/amd64 with 2 cores, 8G of RAM, > a single 1T SSD, with a smallish root/swap/usr, and about 870 GiB free > intended for zfs. I am heading for one po0l that is not raid at all. > > I'm not all that worried about transitions or stability; this is a build > machine for packages, not particularly precious, and it being down for a > week while I fix it is no big deal. > > I will likely pivot the machine to be xen dom0; I hope that doesn't > matter much (other than 1 core only in the dom0). Or I might use nvmm, > or both. > > I might add a spinning disk later, either internal or USB. (I realize > that there, I probably want both ZIL and L2ARC on SSD. I would rather > move bits later than do things now to ease that, since I do not have an > actual plan.) > > My questions are: > > Is 9/current close enough to the same zfs code that it doesn't matter > which I run? If I'm inclined to run current for other reasons, is > that a bad idea zfs-wise? > > I understand that zfs has an intent log always, and that can be within > the pool, or one can add a ZIL device. With the pool having one > device which is an SSD, I see no point in partitioning off part of > that SSD to be the ZIL. > > I understand that zfs has ARC in RAM, and can have L2ARC on disk. > Given that the pool is on SSD, it seems pointless to split off some > for L2ARC. > > My expected answers are: > > The code is basically the same and it doesn't really matter but > probably current has some bugfixes 9 doesn't. There's no reason > current is scary becuase of zfs. I have been using zfs on -current for quite some time; the system gets upgraded 2-3 times a week, no problems so far. > > There is no point in a ZIL on the same SSD as the pool. Yes. > > There is really no point in L2ARC on the same SSD as the pool. Yes. Even if you were to have more physical disks with a different setup, l2arc and zil may not be useful; r/zfs is full with discussions on the topic. 8GB physical memory is enough to run it, but you won't have much left, my system has 20GB, I see at the moment: Memory: 9235M Act, 4606M Inact, 19M Wired, 90M Exec, 13G File, 108M Free But zfs on -current at least is quite usable; I only wonder when OpenZFS 2.0 will be ported... > > > Corrections/clues appreciated. --
zfs: 9 vs current, and ZIL/L2ARC on ssd?
I am about to try to use zfs for the first time and have a few questions. I have a machine that is running NetBSD-9/amd64 with 2 cores, 8G of RAM, a single 1T SSD, with a smallish root/swap/usr, and about 870 GiB free intended for zfs. I am heading for one po0l that is not raid at all. I'm not all that worried about transitions or stability; this is a build machine for packages, not particularly precious, and it being down for a week while I fix it is no big deal. I will likely pivot the machine to be xen dom0; I hope that doesn't matter much (other than 1 core only in the dom0). Or I might use nvmm, or both. I might add a spinning disk later, either internal or USB. (I realize that there, I probably want both ZIL and L2ARC on SSD. I would rather move bits later than do things now to ease that, since I do not have an actual plan.) My questions are: Is 9/current close enough to the same zfs code that it doesn't matter which I run? If I'm inclined to run current for other reasons, is that a bad idea zfs-wise? I understand that zfs has an intent log always, and that can be within the pool, or one can add a ZIL device. With the pool having one device which is an SSD, I see no point in partitioning off part of that SSD to be the ZIL. I understand that zfs has ARC in RAM, and can have L2ARC on disk. Given that the pool is on SSD, it seems pointless to split off some for L2ARC. My expected answers are: The code is basically the same and it doesn't really matter but probably current has some bugfixes 9 doesn't. There's no reason current is scary becuase of zfs. There is no point in a ZIL on the same SSD as the pool. There is really no point in L2ARC on the same SSD as the pool. Corrections/clues appreciated. signature.asc Description: PGP signature
