On 01/08/12 18:21, Bob Friesenhahn wrote:
Something else to be aware of is that even if you don't have a dedicated
ZIL device, zfs will create a ZIL using devices in the main pool so
Terminology nit: The log device is a SLOG. Every ZFS dataset has a
ZIL. Where the ZIL writes (slog or main
2012-01-08 5:45, Richard Elling wrote:
I think you will see a tradeoff on the read side of the mixed read/write
workload.
Sync writes have higher priority than reads so the order of I/O sent to the disk
will appear to be very random and not significantly coalesced. This is the
pathological
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of Bob Friesenhahn
To put things in proper perspective, with 128K filesystem blocks, the
worst case file fragmentation as a percentage is 0.39%
(100*1/((128*1024)/512)). On a Microsoft Windows
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of Jim Klimov
1) Sync writes will land on disk randomly into nearest
(to disk heads) available blocks, in order to have them
committed ASAP;
This is true - but you need to make the distinction
On Jan 9, 2012, at 5:44 AM, Edward Ned Harvey wrote:
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
boun...@opensolaris.org] On Behalf Of Bob Friesenhahn
To put things in proper perspective, with 128K filesystem blocks, the
worst case file fragmentation as a percentage is
On 01/08/12 20:10, Jim Klimov wrote:
Is it true or false that: ZFS might skip the cache and
go to disks for streaming reads?
I don't believe this was ever suggested. Instead, if
data is not already in the file system cache and a
large read is made from disk should the file system
put this
Thanks for the replies, some more questions follow.
Your answers below seem to contradict each other somewhat.
Is it true that:
1) VDEV cache before b70 used to contain a full copy
of prefetched disk contents,
2) VDEV cache since b70 analyzes the prefetched sectors
and only keeps metadata
On 01/08/12 10:15, John Martin wrote:
I believe Joerg Moellenkamp published a discussion
several years ago on how L1ARC attempt to deal with the pollution
of the cache by large streaming reads, but I don't have
a bookmark handy (nor the knowledge of whether the
behavior is still accurate).
2012-01-09 18:15, John Martin пишет:
On 01/08/12 20:10, Jim Klimov wrote:
Is it true or false that: ZFS might skip the cache and
go to disks for streaming reads?
(The more I think
about it, the more senseless this sentence seems, and
I might have just mistaken it with ZIL writes of bulk
On Mon, 9 Jan 2012, Edward Ned Harvey wrote:
I don't think that's correct...
But it is! :-)
Suppose you write a 1G file to disk. It is a database store. Now you start
running your db server. It starts performing transactions all over the
place. It overwrites the middle 4k of the file,
2012-01-09 19:14, Bob Friesenhahn wrote:
In summary, with zfs's default 128K block size, data fragmentation is
not a significant issue, If the zfs filesystem block size is reduced to
a much smaller value (e.g. 8K) then it can become a significant issue.
As Richard Elling points out, a database
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
On 07/01/12 13:39, Jim Klimov wrote:
I have transitioned a number of systems roughly by the same
procedure as you've outlined. Sadly, my notes are not in English so
they wouldn't be of much help directly;
Yes, my russian is rusty :-).
I have
12 matches
Mail list logo
