Hi guys Do anybody have any feedback about CBT support on NFS datastores ? I just wanna make sure those datastores won't be a stepping stone to issues.
I could collect some pieces of information here and there but there is a lot contradictory information on that topic, at least, it seems to me. I understand, and have already noticied in the past, that during the first backup all blocks will be stored even if unused. Moreover, I don't care about thin disk turning into thick upon restoration. According to B/A Client documentation, CBT feature can be enabled: https://www.ibm.com/support/knowledgecenter/SSGSG7_7.1.0/com.ibm.itsm.client.doc/r_cmd_bkupvm.html?lang=en When CBT is enabled, it tracks disk changes when I/O operations are processed by the ESX or ESXi server storage stack on the following disks: - A virtual disk stored on VMFS; the disk can be an iSCSI disk, a local disk, or a disk that is on a SAN. - A virtual disk stored on NFS. - An RDM that is in virtual compatibility mode. Also in this technote, it looks good: http://www-01.ibm.com/support/docview.wss?uid=swg21681916 For non-VMFS volumes or NFS volumes CBT returns an error or a single extent covering the entire VMDK. If an error is thrown, the data mover is forced to create a synthetic extent covering the entire disk. This scenario means that a thin-provisioned VMDK is converted into a thick-provisioned VMDK. The previous statement is always true for thin-provisioned VMDKs on NFS datastores. Also, a thick eager zero provisioned VMDK returns a single extent covering the entire disk because all blocks are allocated and zeroed. After the first full backup the data mover saves the current CBT change ID and uses it to get the incremental data during the next backup. Despite a vmware KB states http://kb.vmware.com/kb/10350 When backing up virtual disk residing on NFS datastores, do not enable CBT, which is a VMFS only feature. Cordialement / Best regards, Christophe COPIN BP2I SP54C Projets et Ingénierie des Infrastructures de Sauvegarde This message and any attachments (the "message") is intended solely for the intended addressees and is confidential. If you receive this message in error,or are not the intended recipient(s), please delete it and any copies from your systems and immediately notify the sender. Any unauthorized view, use that does not comply with its purpose, dissemination or disclosure, either whole or partial, is prohibited. Since the internet cannot guarantee the integrity of this message which may not be reliable, BNP PARIBAS (and its subsidiaries) shall not be liable for the message if modified, changed or falsified. Do not print this message unless it is necessary,consider the environment. ---------------------------------------------------------------------------------------------------------------------------------- Ce message et toutes les pieces jointes (ci-apres le "message") sont etablis a l'intention exclusive de ses destinataires et sont confidentiels. Si vous recevez ce message par erreur ou s'il ne vous est pas destine, merci de le detruire ainsi que toute copie de votre systeme et d'en avertir immediatement l'expediteur. Toute lecture non autorisee, toute utilisation de ce message qui n'est pas conforme a sa destination, toute diffusion ou toute publication, totale ou partielle, est interdite. L'Internet ne permettant pas d'assurer l'integrite de ce message electronique susceptible d'alteration, BNP Paribas (et ses filiales) decline(nt) toute responsabilite au titre de ce message dans l'hypothese ou il aurait ete modifie, deforme ou falsifie. N'imprimez ce message que si necessaire, pensez a l'environnement.
