[ovirt-devel] Re: [EXTERNAL] Re: mismatch in disk size while uploading a disk in chunks using Image Transfer

Thanks Nir. Please see me inline.. From: Nir Soffer <nsoffer(a)redhat.com&gt; Date: Saturday, November 24, 2018 at 12:17 AM To: Ranjit DSouza <Ranjit.DSouza(a)veritas.com&gt; Cc: devel <devel(a)ovirt.org&gt;, Pavan Chavva <pchavva(a)redhat.com&gt;, Suchitra Herwadkar <Suchitra.Herwadkar(a)veritas.com&gt;, Abhay Marode <Abhay.Marode(a)veritas.com&gt; Subject: [EXTERNAL] Re: mismatch in disk size while uploading a disk in chunks using Image Transfer On Fri, Nov 23, 2018 at 2:49 PM Ranjit DSouza <Ranjit.DSouza@veritas.com<mailto:Ranjit.DSouza@veritas.com>> wrote: ... I am trying to upload a snapshot disk in chunks. Everything seems to work fine, but observed that the actual_size after upload, is much lesser than the actual_size of the original disk. Here are the steps: 1. Take a snapshot of a vm disk and download it (using Image Transfer mechanism). Save it on the file system somewhere. This disk name is 3gbdisk. It is Raw + sparse. Resides on nfs storage. The size of this downloaded file is 3 GB. "actual_size" : "1389109248", //1 GB This is the allocated size (what du -sh filename will show). But in 4.2 we do not support yet detection of zero or unallocated areas in the image, so you always download the complete image. Zero or unallocated areas are downloaded as zeros. ... 2. Now create a new floating disk, (raw + sparse), with provisioned_size = 3221225472, or 3 GB. This disk name is vmRestoreDisk 3. Upload to this disk using Image Transfer API, using libCurl in chunks of 128 MB. This is done in a while loop, sequentially reading portions of the file downloaded in step 1 and uploading these chunks via libcurl. I Use the Transfer URL, not proxy URL. Here is the trace of the first chunk. Note the Content-Range and Content-Length headers. Start offset = 0, end offset = 134217727 (or 128 MB) upload request for chunk, start offset: 0, end offset: 134217727 Upload Started Header:Content-Range: bytes 0-134217727/3221225472 The Content-Range header looks correct... Header:Content-Length: 3221225472 * Trying 10.210.46.215... * TCP_NODELAY set * Connected to pnm86hpch30bl15.pne.ven.veritas.com<http://pnm86hpch30bl15.pne.ven.veritas.com> (10.210.46.215) port 54322 (#0) * ALPN, offering http/1.1 * Cipher selection: ALL:!EXPORT:!EXPORT40:!EXPORT56:!aNULL:!LOW:!RC4:@STRENGTH * SSL connection using TLSv1.2 / ECDHE-RSA-AES256-GCM-SHA384 * ALPN, server did not agree to a protocol * Server certificate: * subject: O=pne.ven.veritas.com<http://pne.ven.veritas.com>; CN=pnm86hpch30bl15.pne.ven.veritas.com<http://pnm86hpch30bl15.pne.ven.veritas.com> * start date: Oct 7 08:55:24 2018 GMT * expire date: Oct 7 08:55:24 2023 GMT * issuer: C=US; O=pne.ven.veritas.com<http://pne.ven.veritas.com>; CN=pravauto20.pne.ven.veritas.com.59289 * SSL certificate verify result: unable to get local issuer certificate (20), continuing anyway. Host: pnm86hpch30bl15.pne.ven.veritas.com:54322<http://pnm86hpch30bl15.pne.ven.veritas.com:54322> Accept: */* Content-Length: 134217728 Expect: 100-continue But you did not send the Content-Range header for this request... * Done waiting for 100-continue * We are completely uploaded and fine * HTTP 1.0, assume close after body < HTTP/1.0 200 OK The request was successful, writing the first 128 MiB... < Date: Fri, 23 Nov 2018 11:52:53 GMT < Server: WSGIServer/0.1 Python/2.7.5 < Content-Type: application/json; charset=UTF-8 < Content-Length: 0 < * Closing connection 0 http response code from curl 200 Upload Finished. Return Value: 0 Looking in the attached trace, you never sent the Content-Range, so imageio happily wrote all chunks to the start of the image... 4. Finalize the Image Transfer after all chunks are uploaded. Observed that the disk status goes from ‘uploading via API’ to finalizing to OK. 5. Do a GET call on the disk (vmRestoreDisk). "actual_size" : "134217728", //128MB Which explain why the file size is smaller than expected. "alias" : "vmRestoreDisk", "content_type" : "data", "format" : "raw", "image_id" : "3eda3df2-514a-4e78-b999-1729216b25db", "propagate_errors" : "false", "provisioned_size" : "3221225472", "shareable" : "false", "sparse" : "true", "status" : "ok", "storage_type" : "image", "total_size" : "0", "wipe_after_delete" : "false", As you can see, the actual size is just 128 MB, not 1 GB. I have attached the logs of the upload operation. I think I may be missing something, let me know in case you need further information. Please always include the relevant part from /var/log/ovirt-imageio-daemon/daemon.log If you check this log you will find that all requests for this upload have: WRITE offset=0 size=134217728 ... Other issue I see in the attached trace: - You close the connection after every request - this is not needed and reduce throughput use the same connection for the entire request - libcurl sends "Expect: 100-continue" header, but imageio does not handle this yet in 4.2. This may cause 1 second delay for every request, when libcurl wait for "100 Continue" response, before sending the payload. This feature should be available in 4.3[4]. Until this feature is supported it would be good idea to disable 100-continue header in libcurl[5]. If you cannot disable the option, you can change the timeout[6] to avoid the delay. - You don't check the server capabilities using OPTIONS[0] request. Every upload sholud start by checking the server capabilities so you can optimize the upload using zero and flush operations. - You don't use the ?flush=no query string - this is recommended for improving performance if you use flush=no, you should send PATCH/flush[1] request at the end of the transfer. - It would be more efficient to send bigger chunks. The size of the chunk is depends on the amount of data you like to resend if a request fails. - You can speed up the upload if you detect zero areas in the image and send them using PATCH/zero[2] request. For example using all these features, see imageio python client[3]. If you can use the client you will get all this for free. Otherwise you can use it as example code for implementing the upload in another language. [0] http://ovirt.github.io/ovirt-imageio/random-io.html#options [1] http://ovirt.github.io/ovirt-imageio/random-io.html#zero-operation [2] http://ovirt.github.io/ovirt-imageio/random-io.html#flush-operation [3] https://github.com/oVirt/ovirt-imageio/blob/master/common/ovirt_imageio_c... [4] https://bugzilla.redhat.com/1512324 [5] https://curl.haxx.se/mail/lib-2017-07/0013.html [6] https://curl.haxx.se/libcurl/c/CURLOPT_EXPECT_100_TIMEOUT_MS.html Nir