>>> Strahil Nikolov via Users <users@clusterlabs.org> schrieb am 05.10.2021 um 12:00 in Nachricht <997665166.1212448.1633428038...@mail.yahoo.com>: > These 'dirty' sysctl settings are configureable. For large sequential I/O > it's desirable 'dirty' ratio/bytes to be bigger, while for small files/random > I/O it's better to be kept low.
If random writes are synchronous, it's not relevant anyway, and if they are asynchronous, a larger dirty buffer pool will boost write performance (allowing to sort/merge requests before writing). For sequential writes large buffers don't help a lot. > > Best Regards, > Strahil Nikolov > > > > > > > В вторник, 5 октомври 2021 г., 08:52:20 ч. Гринуич+3, Ulrich Windl > <ulrich.wi...@rz.uni-regensburg.de> написа: > > > > > >>>> Gang He via Users <users@clusterlabs.org> schrieb am 30.09.2021 um 03:55 > in > Nachricht <afb3d125-3573-a12f-406f-96724eaf1...@suse.com>: > >> >> On 2021/9/29 16:20, Lentes, Bernd wrote: >>> >>> >>> ‑‑‑‑‑ On Sep 29, 2021, at 4:37 AM, Gang He g...@suse.com wrote: >>> >>>> Hi Lentes, >>>> >>>> Thank for your feedback. >>>> I have some questions as below, >>>> 1) how to clone these VM images from each ocfs2 nodes via reflink? >>>> do you encounter any problems during this step? >>>> I want to say, this is a shared file system, you do not clone all VM >>>> images from each node, duplicated. >>>> 2) after the cloned VM images are created, how do you copy these VM >>>> images? copy to another backup file system, right? >>>> The problem usually happened during this step? >>>> >>>> Thanks >>>> Gang >>> >>> 1) No problems during this step, the procedure just needs a few seconds. >>> reflink is a binary. See reflink ‑‑help >>> Yes, it is a cluster filesystem. I do the procedure just on one node, >>> so i don't have duplicates. >>> >>> 2) just with "cp source destination" to a NAS. >>> Yes, the problems appear during this step. > >> Ok, when you cp the cloned file to the NAS directory, >> the NAS directory should be another file system, right? >> During the copying process, the original VM running will be affected, >> right? > > One issue, especially with large RAM systems is this: If you copy from a > fast > to a slow device, the RAM wil fil with dirty buffers, probably causing a > read > starvation (no discardable buffer available). So this can affect any > unlelated > process. > (Actually in the past it affected the IPaddr monitor for us) > However I think recent kernels (maybe it's SUSE specific) prevent the whole > free RAM to be filled with dirty buffers. > > Regards, > Ulrich > >> >> Thanks >> Gang >> >>> >>> Bernd >>> >> >> _______________________________________________ >> Manage your subscription: >> https://lists.clusterlabs.org/mailman/listinfo/users >> >> ClusterLabs home: https://www.clusterlabs.org/ > > > > > _______________________________________________ > Manage your subscription: > https://lists.clusterlabs.org/mailman/listinfo/users > > ClusterLabs home: https://www.clusterlabs.org/ > _______________________________________________ > Manage your subscription: > https://lists.clusterlabs.org/mailman/listinfo/users > > ClusterLabs home: https://www.clusterlabs.org/ _______________________________________________ Manage your subscription: https://lists.clusterlabs.org/mailman/listinfo/users ClusterLabs home: https://www.clusterlabs.org/
