[sheepdog] [PATCH] new feature of changing the replica number of existing cluster/vdi
Hitoshi Mitake
mitake.hitoshi at gmail.com
Fri May 16 17:00:45 CEST 2014
At Mon, 12 May 2014 18:31:42 +0800,
Ruoyu wrote:
>
> 1. to set the replica number of cluster:
> dog cluster copies <num>
>
> 2. to set the replica number of vdi:
> dog vdi copies <vdiname> <num>
>
> Signed-off-by: Ruoyu <liangry at ucweb.com>
> ---
> dog/cluster.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++
> dog/vdi.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++
> include/internal_proto.h | 2 ++
> sheep/ops.c | 43 ++++++++++++++++++++++++++++
> 4 files changed, 191 insertions(+)
I think changing copy number of vdi is dangerous. Assume that we are
changing copy number of VDI A from 3 to 2 which has a snapshot B.
Your cluster_set_vdi_copies() starts recovery process but it cannot
change a number of copies actually because some of A's objects would
have B's VID (B has younger VID), and get_vdi_copy_number() returns
copy number based on VID part of OID. It introduces inconsistency.
So I think you should forbid changing a number of copies when VDI has
a parent or children. The changing would be similar to exporting VDI
with qemu-img once and backporting with different number of
copies. But the procedure requires lots of temporal space for storing
disk image (which can be few TBs), so preparing a new command which
can change a number of copies without requireing temporal space would
be worthful.
Thanks,
Hitoshi
>
> diff --git a/dog/cluster.c b/dog/cluster.c
> index 4af1e7c..6dd2ca6 100644
> --- a/dog/cluster.c
> +++ b/dog/cluster.c
> @@ -545,6 +545,77 @@ static int cluster_check(int argc, char **argv)
> return EXIT_SUCCESS;
> }
>
> +#define SET_COPIES_PRINT \
> + " __\n" \
> + " ()'`;\n" \
> + " /\\|` Caution! Changing the # of replica will affect\n" \
> + " / | all the VDIs to be created later.\n" \
> + "(/_)_|_ Are you sure you want to continue? [yes/no]: "
> +
> +static int cluster_copies(int argc, char **argv)
> +{
> + int ret, log_length;
> + struct sd_req hdr;
> + struct sd_rsp *rsp = (struct sd_rsp *)&hdr;
> + struct epoch_log *logs;
> +
> + cluster_cmd_data.copies = parse_copy(argv[optind],
> + &cluster_cmd_data.copy_policy);
> + if (cluster_cmd_data.copy_policy != 0) {
> + sd_err("changing the replica number to erasure code is not supported yet.");
> + return EXIT_USAGE;
> + }
> + if (cluster_cmd_data.copies <= 0) {
> + sd_err("invalid replica number.");
> + return EXIT_USAGE;
> + }
> +
> + log_length = sd_epoch * sizeof(struct epoch_log);
> + logs = xmalloc(log_length);
> + sd_init_req(&hdr, SD_OP_STAT_CLUSTER);
> + hdr.data_length = log_length;
> + ret = dog_exec_req(&sd_nid, &hdr, logs);
> + if (ret < 0)
> + goto failure;
> +
> + if (rsp->result != SD_RES_SUCCESS) {
> + sd_err("Response's result: %s", sd_strerror(rsp->result));
> + goto failure;
> + }
> + if (logs->copy_policy) {
> + sd_err("the cluster's copy policy is erasure code, "
> + "changing it is not supported yet.");
> + goto failure;
> + }
> + if (logs->nr_copies == cluster_cmd_data.copies) {
> + sd_err("the cluster's replica number is already set to %d.",
> + cluster_cmd_data.copies);
> + goto failure;
> + }
> +
> + confirm(SET_COPIES_PRINT);
> +
> + sd_init_req(&hdr, SD_OP_SET_CLUSTER_COPIES);
> + hdr.cluster.copies = cluster_cmd_data.copies;
> + hdr.cluster.copy_policy = cluster_cmd_data.copy_policy;
> + ret = send_light_req(&sd_nid, &hdr);
> + if (ret == 0) {
> + sd_info("the cluster's replica number is set to %d, the old one was %d.",
> + cluster_cmd_data.copies, logs->nr_copies);
> + goto success;
> + } else {
> + sd_err("set the cluster's replica number failure.");
> + goto failure;
> + }
> +
> +success:
> + free(logs);
> + return EXIT_SUCCESS;
> +failure:
> + free(logs);
> + return EXIT_FAILURE;
> +}
> +
> static struct subcommand cluster_cmd[] = {
> {"info", NULL, "aprhs", "show cluster information",
> NULL, CMD_NEED_NODELIST, cluster_info, cluster_options},
> @@ -563,6 +634,8 @@ static struct subcommand cluster_cmd[] = {
> cluster_reweight, cluster_options},
> {"check", NULL, "aph", "check and repair cluster", NULL,
> CMD_NEED_NODELIST, cluster_check, cluster_options},
> + {"copies", "<num>", "aph", "set the cluster's replica number", NULL,
> + CMD_NEED_ARG|CMD_NEED_NODELIST, cluster_copies, cluster_options},
> {NULL,},
> };
>
> diff --git a/dog/vdi.c b/dog/vdi.c
> index 4d7fd54..f8f2421 100644
> --- a/dog/vdi.c
> +++ b/dog/vdi.c
> @@ -2346,6 +2346,76 @@ static int vdi_cache(int argc, char **argv)
> return do_generic_subcommand(vdi_cache_cmd, argc, argv);
> }
>
> +#define SET_COPIES_PRINT \
> + " __\n" \
> + " ()'`;\n" \
> + " /\\|` Caution! Changing the # of replica will affect\n" \
> + " / | the specified VDI and trigger recovery.\n" \
> + "(/_)_|_ Are you sure you want to continue? [yes/no]: "
> +
> +static int vdi_copies(int argc, char **argv)
> +{
> + int ret, old_nr_copies;
> + uint32_t vid;
> + const char *vdiname = argv[optind++];
> + char buf[SD_INODE_HEADER_SIZE];
> + struct sd_inode *inode = (struct sd_inode *)buf;
> + struct sd_req hdr;
> +
> + vdi_cmd_data.nr_copies = parse_copy(argv[optind],
> + &vdi_cmd_data.copy_policy);
> + if (vdi_cmd_data.copy_policy != 0) {
> + sd_err("changing the replica number to erasure code is not supported yet.");
> + return EXIT_USAGE;
> + }
> + if (vdi_cmd_data.nr_copies <= 0) {
> + sd_err("invalid replica number.");
> + return EXIT_USAGE;
> + }
> +
> + ret = read_vdi_obj(vdiname, 0, "", &vid, inode, SD_INODE_HEADER_SIZE);
> + if (ret != EXIT_SUCCESS) {
> + sd_err("read %s's vdi object failure.", vdiname);
> + return EXIT_FAILURE;
> + }
> + if (inode->copy_policy) {
> + sd_err("%s's copy policy is erasure code, "
> + "changing it is not supported yet.", vdiname);
> + return EXIT_FAILURE;
> + }
> + old_nr_copies = inode->nr_copies;
> + if (old_nr_copies == vdi_cmd_data.nr_copies) {
> + sd_err("%s's replica number is already set to %d.",
> + vdiname, old_nr_copies);
> + return EXIT_FAILURE;
> + }
> +
> + confirm(SET_COPIES_PRINT);
> +
> + inode->nr_copies = vdi_cmd_data.nr_copies;
> + ret = dog_write_object(vid_to_vdi_oid(vid), 0, inode,
> + SD_INODE_HEADER_SIZE, 0, 0, old_nr_copies,
> + inode->copy_policy, false, true);
> + if (ret != SD_RES_SUCCESS) {
> + sd_err("overwrite the vdi object's header of %s failure "
> + "while setting its replica number.", vdiname);
> + return EXIT_FAILURE;
> + }
> +
> + sd_init_req(&hdr, SD_OP_SET_VDI_COPIES);
> + hdr.vdi_state.new_vid = vid;
> + hdr.vdi_state.copies = vdi_cmd_data.nr_copies;
> +
> + ret = send_light_req(&sd_nid, &hdr);
> + if (ret == 0) {
> + sd_info("%s's replica number is set to %d, the old one was %d.",
> + vdiname, vdi_cmd_data.nr_copies, old_nr_copies);
> + return EXIT_SUCCESS;
> + }
> + sd_err("set %s's replica number failure.", vdiname);
> + return EXIT_FAILURE;
> +}
> +
> static struct subcommand vdi_cmd[] = {
> {"check", "<vdiname>", "saph", "check and repair image's consistency",
> NULL, CMD_NEED_NODELIST|CMD_NEED_ARG,
> @@ -2402,6 +2472,9 @@ static struct subcommand vdi_cmd[] = {
> {"cache", "<vdiname>", "saph", "Run 'dog vdi cache' for more information",
> vdi_cache_cmd, CMD_NEED_ARG,
> vdi_cache, vdi_options},
> + {"copies", "<vdiname> <num>", "aph", "set the vdi's replica number",
> + NULL, CMD_NEED_NODELIST|CMD_NEED_ARG,
> + vdi_copies, vdi_options},
> {NULL,},
> };
>
> diff --git a/include/internal_proto.h b/include/internal_proto.h
> index 0eb7227..4e95e55 100644
> --- a/include/internal_proto.h
> +++ b/include/internal_proto.h
> @@ -101,6 +101,8 @@
> #define SD_OP_NFS_DELETE 0xBC
> #define SD_OP_EXIST 0xBD
> #define SD_OP_CLUSTER_INFO 0xBE
> +#define SD_OP_SET_CLUSTER_COPIES 0xC0
> +#define SD_OP_SET_VDI_COPIES 0xC1
>
> /* internal flags for hdr.flags, must be above 0x80 */
> #define SD_FLAG_CMD_RECOVERY 0x0080
> diff --git a/sheep/ops.c b/sheep/ops.c
> index b9550f0..523dfbc 100644
> --- a/sheep/ops.c
> +++ b/sheep/ops.c
> @@ -714,6 +714,35 @@ static int cluster_recovery_completion(const struct sd_req *req,
> return SD_RES_SUCCESS;
> }
>
> +static int cluster_set_cluster_copies(const struct sd_req *req,
> + struct sd_rsp *rsp, void *data)
> +{
> + if (req->cluster.copy_policy != 0)
> + return SD_RES_INVALID_PARMS;
> +
> + sys->cinfo.nr_copies = req->cluster.copies;
> + return set_cluster_config(&sys->cinfo);
> +}
> +
> +static int cluster_set_vdi_copies(const struct sd_req *req,
> + struct sd_rsp *rsp, void *data)
> +{
> + if (req->cluster.copy_policy != 0)
> + return SD_RES_INVALID_PARMS;
> +
> + uint32_t vid = req->vdi_state.new_vid;
> + int nr_copies = req->vdi_state.copies;
> + struct vnode_info *vinfo;
> +
> + add_vdi_state(vid, nr_copies, false, 0);
> +
> + vinfo = get_vnode_info();
> + start_recovery(vinfo, vinfo, false);
> + put_vnode_info(vinfo);
> +
> + return SD_RES_SUCCESS;
> +}
> +
> static bool node_size_varied(void)
> {
> uint64_t new, used, old = sys->this_node.space;
> @@ -1179,6 +1208,20 @@ static struct sd_op_template sd_ops[] = {
> .process_main = cluster_disable_recover,
> },
>
> + [SD_OP_SET_CLUSTER_COPIES] = {
> + .name = "SET_CLUSTER_COPIES",
> + .type = SD_OP_TYPE_CLUSTER,
> + .is_admin_op = true,
> + .process_main = cluster_set_cluster_copies,
> + },
> +
> + [SD_OP_SET_VDI_COPIES] = {
> + .name = "SET_VDI_COPIES",
> + .type = SD_OP_TYPE_CLUSTER,
> + .is_admin_op = true,
> + .process_main = cluster_set_vdi_copies,
> + },
> +
> /* local operations */
> [SD_OP_RELEASE_VDI] = {
> .name = "RELEASE_VDI",
> --
> 1.8.3.2
>
>
> --
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