From: Dominik Csapak <d.csapak@proxmox.com>
To: pbs-devel@lists.proxmox.com
Subject: [pbs-devel] [PATCH proxmox-backup v2] fix #5229: tape: remove max sequence number limit
Date: Mon, 12 Feb 2024 13:27:34 +0100 [thread overview]
Message-ID: <20240212122734.1991317-1-d.csapak@proxmox.com> (raw)
The idea was to limit the number of tapes in a media set, but this was
not enforced when adding a medium to a media set, only on read/parsing
the inventory. With that, it is possible to create media sets greater
than the limit which in turn blocks access to most functions via
api/cli/gui due to the check.
Instead of enforcing an arbitrary limit, simply warn on creation when
the media-set is very large (20).
To restore the whole media set, the time taken would still be at least 38
hours for LTO-4 and 250 hours for LTO-9.
We already have a section in the docs where we tell about the
disadvantages of large media sets.
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
changes from v1:
* better sentence in commit message about restore time
* keep the limit as a constant (but with a different name, at different
location)
src/tape/media_set.rs | 10 ----------
src/tape/pool_writer/mod.rs | 12 ++++++++++++
2 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/src/tape/media_set.rs b/src/tape/media_set.rs
index 8c08efd9..894c8ae3 100644
--- a/src/tape/media_set.rs
+++ b/src/tape/media_set.rs
@@ -13,8 +13,6 @@ pub struct MediaSet {
}
impl MediaSet {
- pub const MEDIA_SET_MAX_SEQ_NR: u64 = 100;
-
#[allow(clippy::new_without_default)]
pub fn new() -> Self {
let uuid = Uuid::generate();
@@ -41,14 +39,6 @@ impl MediaSet {
}
pub fn insert_media(&mut self, uuid: Uuid, seq_nr: u64) -> Result<(), Error> {
- if seq_nr > Self::MEDIA_SET_MAX_SEQ_NR {
- bail!(
- "media set sequence number to large in media set {} ({} > {})",
- self.uuid.to_string(),
- seq_nr,
- Self::MEDIA_SET_MAX_SEQ_NR
- );
- }
let seq_nr = seq_nr as usize;
if self.media_list.len() > seq_nr {
if self.media_list[seq_nr].is_some() {
diff --git a/src/tape/pool_writer/mod.rs b/src/tape/pool_writer/mod.rs
index f1224bdd..a6ba4a1d 100644
--- a/src/tape/pool_writer/mod.rs
+++ b/src/tape/pool_writer/mod.rs
@@ -32,6 +32,10 @@ use super::file_formats::{
PROXMOX_BACKUP_CATALOG_ARCHIVE_MAGIC_1_0, PROXMOX_BACKUP_CATALOG_ARCHIVE_MAGIC_1_1,
};
+// Warn when the sequence number reaches this limit, as large
+// media sets are error prone and take a very long time to restore from.
+const MEDIA_SET_SEQ_NR_WARN_LIMIT: u64 = 20;
+
struct PoolWriterState {
drive: Box<dyn TapeDriver>,
// Media Uuid from loaded media
@@ -272,6 +276,14 @@ impl PoolWriter {
let media_set = media.media_set_label().unwrap();
+ if is_new_media && media_set.seq_nr >= MEDIA_SET_SEQ_NR_WARN_LIMIT {
+ task_warn!(
+ worker,
+ "large media-set detected ({}), consider using a different allocation policy",
+ media_set.seq_nr
+ );
+ }
+
drive.assert_encryption_mode(media_set.encryption_key_fingerprint.is_some())?;
self.status = Some(PoolWriterState {
--
2.30.2
next reply other threads:[~2024-02-12 12:28 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-12 12:27 Dominik Csapak [this message]
2024-02-12 13:06 ` [pbs-devel] applied: " Dietmar Maurer
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